Nozzles For Amplifying And Suppression Of Sound

Abstract

The invention discloses a novel passive sound transformer, either a sound-booster or a sound-silencer, embodied as an acoustic waveguide, a specific shape of which provides for either amplifying the intensity of acoustic waves at the expense of both the heat energy and the concomitant turbulence of moving fluid wherein the amplified intensity of the acoustic waves is manifested as sound loudness boosting or, contrarywise, transforming the wave power of elastic waves into the heat of the ambient fluid.

Claims

1. A.sub.n acoustic nozzle [2.A, 2.B, 2.C, 3.A]; the acoustic nozzle comprising a solid corpus submerged in fluid and exposed to sound, audible or ultrasonic, propagating in the fluid; said solid corpus comprising an inner canal having: an open sound-inlet having a sound-inlet cross-sectional area, indicated by A.sub.IN; an open sound-outlet having a sound-outlet cross-sectional area, indicated by A.sub.OU; and a varying cross-sectional area, varying along the canal length, thereby, forming a shaped through-hole tunnel-waveguide being either converging, divergent, convergent-divergent, divergent-convergent, two-stage convergent-divergent; wherein: an M-velocity is defined as a velocity measured in Mach numbers; and a sound is specified as a complicated movement of molecules of the fluid, wherein the complicated movement comprising motion components as follows: the Brownian motion of the molecules of the fluid; an oscillating motion of the molecules of the fluid, wherein the oscillation motion occurs with an oscillating particle velocity; a conveying motion of a tiny mass of the fluid in a direction of sound propagation; the tiny mass is the positive and negative changes in the mass density which is a result of the oscillating motion of the molecules, specifically synchronized in phase such that providing headway motion of the positive and negative changes in fluid mass density in the direction of the sound propagation, wherein the conveying motion of the tiny mass of the fluid occurring with a velocity of sound in the fluid; and turbulent motion of groups of the molecules of the fluid; wherein: the open sound-inlet is exposed to ambient sound entering into and propagating within the inner canal and, thereby, the fluid within the shaped through-hole tunnel-waveguide is subjected to the propagating sound performing a complicated movement of the fluid; the shaped through-hole tunnel-waveguide is characterized by a cross-sectional area profile smooth function A(x) of x-coordinates, where the x-coordinates are defined as increasing in a direction of sound propagation; wherein at least one portion, either converging, divergent, or convergent-divergent, of the shaped through-hole tunnel-waveguide, is characterized by a cross-sectional area profile function A.sub.NOZZLE(x), specified as a reference equation expressed as: $A_{\mathrm{NOZZLE}}\left(x\right)=\frac{A_{*}}{M\left(x\right)}{\left(\frac{\gamma -1}{\gamma }\right)}^{\frac{1}{2}}{\left(\frac{2+{\gamma \left(M\left(x\right)\right)}^2}{\gamma +1}\right)}^{\frac{\gamma +1}{2\left(\gamma -1\right)}},x_a<x<x_b$ where γ is an adiabatic compressibility parameter of a portion of fluid, x.sub.a and x.sub.b are x-coordinates of the portion's beginning and end, correspondingly, M(x) is a gradual smooth function of x representing a profile of an M-velocity of a tiny mass of the fluid motion within the shaped through-hole tunnel-waveguide, and A.sub.* is a constant satisfying a condition $\frac{A_{\mathrm{IN}}}{A_{*}}\ge \sqrt{\left(\frac{\gamma -1}{\gamma }\right){\left(\frac{2+\gamma }{\gamma +1}\right)}^{\frac{\gamma +1}{\left(\gamma -1\right)}}};$ thereby, providing for that the acoustic nozzle functions as either: a sound-booster, to: solve a problem of sound power dissipation into heat energy of fluid, convey the sound from the open sound-inlet to the open sound-outlet, and amplify loudness of the sound at the expense of both the heat energy of fluid and concomitant turbulence of the fluid; or, contrariwise, a sound-silencer, to suppress a waveguide effect and transform the sound's intensity into ambient heat thereby solving a problem of sound propagation.

2. A divergent horn sound-booster [2.A]; the divergent horn sound-booster comprising the acoustic nozzle of claim 1, wherein the inner canal is configured as a divergent pipe diverging from the open sound-inlet to the open sound-outlet, wherein the cross-sectional profile function A(x) is further specified as a divergent cross-sectional profile function A.sub.HORN(x) derived from the reference equation restricted by condition $\frac{A_{\mathrm{IN}}}{A_{*}}=\sqrt{\left(\frac{\gamma -1}{\gamma }\right){\left(\frac{2+\gamma }{\gamma +1}\right)}^{\frac{\gamma +1}{\left(\gamma -1\right)}}}$ and expressed as an equation of horn: $A_{\mathrm{HORN}}\left(x\right)=\frac{A_{\mathrm{IN}}}{M_{\mathrm{HORN}}\left(x\right)}{\left(\frac{2+{\gamma \left(M_{\mathrm{HORN}}\left(x\right)\right)}^2}{2+\gamma }\right)}^{\frac{\gamma +1}{2\left(\gamma -1\right)}},x_a<x<x_b,$ where x.sub.a and x.sub.b are x-coordinates of the open sound-inlet and open sound-outlet, correspondingly, and M.sub.HORN(x) is a monotonically-increasing gradually-smooth function of x representing an M-velocity profile of the fluid tiny portion moving within and through the divergent horn sound-booster.

3. A brokenly-cascaded waveguiding sound-booster [2.A40] comprising a broken through-hole tunnel-waveguide formed by an in-line arranged brokenly-cascaded array of a multiplicity of the divergent horn sound-boosters of claim 2; the brokenly-cascaded waveguiding sound-booster has: a broken corpus, broken by at least one open space, and the divergent horn sound-boosters, indicated by index n enumerated from 1 to N, wherein N is defined as at least 2; wherein each n-th divergent horn sound-booster comprises: an open sound-inlet having a sound-inlet cross-sectional area of A.sub.IN,n; an open sound-outlet having a sound-outlet cross-sectional area of A.sub.OU,n; a condition A.sub.OU,n>A.sub.IN,n is satisfied; and a varying cross-sectional area, varying along the canal length thereby forming a shaped through-hole tunnel-waveguide being divergent and characterized by a cross-sectional area profile function A.sub.n(x); wherein: a cross-sectional area profile broken function of the waveguiding sound-booster as a whole is a piecewise-broken-with-intervals piecewise-divergent cross-sectional area profile function A.sub.BROKEN(x) comprising portions A.sub.n(x), n=1, 2, . . . , N, associated with the n-th divergent horn sound-boosters, correspondingly, wherein the n-th cross-sectional area profile function A.sub.n(x) is expressed as: $A_n\left(x\right)=\frac{A_{\mathrm{IN},n}}{M_n\left(x\right)}{\left(\frac{2+{\gamma \left(M_n\left(x\right)\right)}^2}{2+\gamma }\right)}^{\frac{\gamma +1}{2\left(\gamma -1\right)}},x_{a,n}<x<x_{b,n},n=1,2,\mathrm{.Math.},N,$ where x.sub.a,n and x.sub.b,n are x-coordinates of the open sound-inlet and open sound-outlet, correspondingly, of the n-th divergent horn, and M.sub.n(x) is an n-th monotonically-increasing gradually-smooth function of x representing an M-velocity profile of the fluid tiny portion moving within and through the n-th divergent horn; and the N divergent horn sound-boosters are arranged sequentially one after another with intervals of open space such that a portion of the propagating sound sequentially: enters the open sound-inlet of each n-th divergent horn sound-booster, propagates within the n-th divergent horn sound-booster, reaches the open sound-outlet of the n-th divergent horn sound-booster, becomes launched from the open sound-outlet of the n-th divergent horn sound-booster, while n<N, enters the interval of open space between the n-th and (n+1)-th divergent horn sound-boosters, and when n=N, becomes a resulting acoustic beam launched from the open sound-outlet of the N-th divergent horn sound-booster and characterized by an increased intensity manifested as boosted sound loudness.

4. A phonendoscope [2.B, 2.C]; the phonendoscope comprising the acoustic nozzle of claim 1, wherein the inner canal is configured as a two-stage convergent-divergent tunnel comprising three sequentially joint fragments as follows: A first convergent-divergent fragment; A divergent-convergent cavity; and A second convergent-divergent fragment; wherein: said open sound-inlet having the sound-inlet cross-sectional area, indicated by A.sub.IN, is an open sound-inlet of the first convergent-divergent fragment, said open sound-outlet having the sound-inlet cross-sectional area, indicated by A.sub.OU, is an open sound-outlet of the second convergent-divergent fragment, and the divergent-convergent cavity has a local maximal cross-sectional area, indicated by A.sub.CA; the cross-sectional area profile smooth function A(x) is composed of sequentially concatenated cross-sectional area profile functions A.sub.1(x), A.sub.CA(x), and A.sub.2 (x), wherein: A.sub.1(x) is cross-sectional area profile function of the first convergent-divergent fragment, which provides for the enhanced de Laval retarding-effect resulting in deceleration of the fluid tiny portion, A.sub.2(x) is cross-sectional area profile function of the second convergent-divergent fragment, which provides for the enhanced de Laval jet-effect resulting in acceleration of the fluid tiny portion, and the cross-sectional area profile functions A.sub.1(x) and A.sub.2(x) are given by the equations expressed as: $\hspace{1em}\{\begin{array}{cc}{A}_1\left(x\right)=\frac{A_{\mathrm{TH}1}}{M_1\left(x\right)}{\left(\frac{\gamma -1}{\gamma }\right)}^{\frac{1}{2}}{\left(\frac{2+{\gamma \left(M_1\left(x\right)\right)}^2}{\gamma +1}\right)}^{\frac{\gamma +1}{2\left(\gamma -1\right)}},& x_{a,1}<x<x_{b,1}\\ A_2\left(x\right)=\frac{A_{\mathrm{TH}2}}{M_2\left(x\right)}{\left(\frac{\gamma -1}{\gamma }\right)}^{\frac{1}{2}}{\left(\frac{2+{\gamma \left(M_2\left(x\right)\right)}^2}{\gamma +1}\right)}^{\frac{\gamma +1}{2\left(\gamma -1\right)}},& x_{a,2}<x<x_{b,2}\end{array}$ where: x.sub.a,1 and x.sub.b,1 are x-coordinates of the open sound-inlet and open sound-outlet, correspondingly, of the first convergent-divergent fragment, x.sub.a,2 and x.sub.b,2 are x-coordinates of the open sound-inlet and open sound-outlet, correspondingly, of the second convergent-divergent fragment, M.sub.1(x) is a monotonically-decreasing gradually-smooth function of x, M.sub.2(x) is a monotonically-increasing gradually-smooth function of x, and A.sub.TH1 and A.sub.TH2 are local minimal cross-sectional areas of narrow throats of the first and second convergent-divergent fragments, correspondingly; A.sub.CA(x) is cross-sectional area profile function of the divergent-convergent cavity defined between x.sub.b,1 and x.sub.a,2 such that providing for the enhanced Venturi effect as a gradually-smooth function M.sub.CA(x) of x, representing an M-velocity profile of the tiny portion of the fluid moving in the divergent-convergent cavity between the first and second narrow throats, remains lower than the specific M-velocity M.sub.*=√{square root over ((γ−1)/γ)}; M.sub.1(x), M.sub.CA(x), and M.sub.2(x) are sequentially-concatenated to form a gradually-smooth function M(x) of x, representing an M-velocity profile of the fluid tiny portion moving within and through the two-stage convergent-divergent nozzle's through-hole tunnel-waveguide; and interrelations between the cross-sectional areas A.sub.IN, A.sub.TH1, A.sub.CA, A.sub.TH2, and A.sub.OU satisfying conditions as follows: $\begin{array}{cc}\frac{A_{\mathrm{IN}}}{A_{\mathrm{TH}1}}\ge \sqrt{\left(\frac{\gamma -1}{\gamma }\right){\left(\frac{2+\gamma }{\gamma +1}\right)}^{\frac{\gamma +1}{\left(\gamma -1\right)}}},& \left(f\right)\\ A_{\mathrm{CA}}>A_{\mathrm{TH}1},& \left(g\right)\\ A_{\mathrm{CA}}>A_{\mathrm{TH}2},& \left(h\right)\\ A_{\mathrm{TH}1}\ge A_{\mathrm{TH}2},\mathrm{and}& \left(i\right)\\ \frac{A_{\mathrm{OU}}}{A_{\mathrm{TH}2}}>\sqrt{\left(\frac{\gamma -1}{\gamma }\right){\left(\frac{2+\gamma }{\gamma +1}\right)}^{\frac{\gamma +1}{\left(\gamma -1\right)}}};& \left(j\right)\end{array}$ thereby providing for that, a portion of the propagating sound, entering the open sound-inlet, propagating through the two-stage convergent-divergent tunnel, and becoming launched from the open sound-outlet, becomes characterized by an amplified loudness.

5. The phonendoscope [2.C] of claim 4, wherein said solid corpus [2.C1] has an outer geometrical configuration ergonomically adapted to a human's ear, thereby providing that, when the open sound-inlet is exposed to ambient sound and the open sound-outlet is faced to an eardrum within the human's ear canal, the acoustic nozzle becomes capable of amplifying a loudness of a portion of sound yet to become entering the human's ear canal.

6. A sound-silencer [3.A]; the sound-silencer comprising the acoustic nozzle of claim 1, wherein the inner canal is configured as a convergent-divergent pipe comprising: a converging funnel having the open sound-inlet [3.A1], a divergent exhaust tailpipe having the open sound-outlet [3.A2], and a narrow throat [3.A4] between the converging funnel and divergent exhaust tailpipe; wherein the cross-sectional profile function A(x) is further specified as a convergent-divergent cross-sectional profile function A.sub.SILENCER(x) expressed as: $A_{\mathrm{SILENCER}}\left(x\right)=\frac{A_{*\mathrm{SILENCER}}}{M_{\mathrm{SILENCER}}\left(x\right)}{\left(\frac{\gamma -1}{\gamma }\right)}^{\frac{1}{2}}{\left(\frac{2+{\gamma \left(M_{\mathrm{SILENCER}}\left(x\right)\right)}^2}{\gamma +1}\right)}^{\frac{\gamma +1}{2\left(\gamma -1\right)}},x_a<x<x_b$ where x.sub.a and x.sub.b are x-coordinates of the open sound-inlet and open sound-outlet, correspondingly, M.sub.SILENCER (x) is a monotonically-decreasing gradually-smooth function of x representing an M-velocity profile of the fluid tiny portion moving within and through the convergent-divergent sound-silencer, and A.sub.*SILENCER is a constant, being lesser than both the cross-sectional area of the open sound-inlet A.sub.IN and the cross-sectional area of the open sound-outlet A.sub.OU and having a sense of a minimal cross-sectional area of the narrow throat between the converging funnel and divergent exhaust tailpipe, wherein the condition $\frac{A_{\mathrm{IN}}}{A_{*\mathrm{SILENCER}}}=\sqrt{\left(\frac{\gamma -1}{\gamma }\right){\left(\frac{2+\gamma }{\gamma +1}\right)}^{\frac{\gamma +1}{\left(\gamma -1\right)}}}$ is satisfied.

7. A brokenly-cascaded sound-silencer [3.B40] comprising a broken pipe formed by an in-line arranged brokenly-cascaded array of a multiplicity of the sound-silencer of claim 6; the brokenly-cascaded sound-silencer has: a broken corpus, broken by at least one open space, and the sound-silencers, indicated by index n enumerated from 1 to N, wherein N is defined as at least 2; wherein each n-th sound-silencer comprises: an open sound-inlet having a sound-inlet cross-sectional area of A.sub.IN,n; an open sound-outlet having a sound-outlet cross-sectional area of A.sub.OU,n; and a varying cross-sectional area, varying along the canal length thereby forming a shaped pipe being convergent-divergent and characterized by a cross-sectional area profile function A.sub.n(x); wherein: a cross-sectional area profile broken function of the brokenly-cascaded sound-silencer as a whole is a piecewise-broken-with-intervals piecewise-convergent-divergent cross-sectional area profile function A.sub.BROKEN(x) comprising portions A.sub.n(x), n 1, 2, . . . , N, associated with the n-th sound-silencer, correspondingly, wherein the n-th cross-sectional area profile function A.sub.n(x) is expressed as: $A_n\left(x\right)=\frac{A_{*n}}{M_n\left(x\right)}{\left(\frac{\gamma -1}{\gamma }\right)}^{\frac{1}{2}}{\left(\frac{2+{\gamma \left(M_n\left(x\right)\right)}^2}{\gamma +1}\right)}^{\frac{\gamma +1}{2\left(\gamma -1\right)}},x_{a,n}<x<x_{b,n}n=1,2,\mathrm{.Math.},N$ where x.sub.a,n and x.sub.b,n are x-coordinates of the open sound-inlet and open sound-outlet, correspondingly, of the n-th sound-silencer, and M.sub.n(x) is an n-th monotonically-decreasing gradually-smooth function of x representing an M-velocity profile of the fluid tiny portion moving within and through the n-th sound-silencer; and the N sound-silencers are arranged sequentially one after another with intervals of open space such that a portion of the propagating sound sequentially: enters the open sound-inlet of each n-th sound-silencer, propagates within the n-th sound-silencer, reaches the open sound-outlet of the n-th sound-silencer, becomes launched from the open sound-outlet of the n-th sound-silencer, while n<N, enters the interval of open space between the n-th and (n+1)-th sound-silencer, and when n=N, becomes a resulting acoustic beam launched from the open sound-outlet of the N-th sound-silencer and characterized by a decreased intensity manifested as suppressed sound loudness.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0172] To understand the invention and to see how it may be carried out in practice, a preferred embodiment will now be described, by way of a non-limiting example only, with reference to the accompanying drawings, in the drawings:

[0173] FIG. 1b is a prior art schematic drawing of the convergent-divergent Venturi tube;

[0174] FIG. 1c is a prior art schematic view of the convergent-divergent de Laval nozzle;

[0175] FIG. 1d is a prior art schematic illustration graphics of gas velocity, static pressure, and temperature distributions within the de Laval convergent-divergent jet-nozzle;

[0176] FIG. 1e is a prior art schematic illustration of an optimized convergent-divergent jet-nozzle;

[0177] FIG. 1f is a prior art schematic illustration of an optimized inverse convergent-divergent jet-nozzle;

[0178] FIG. 1g is a prior art schematic illustration of a two-stage convergent-divergent jet-nozzle, constructed according to the principles of the present invention;

[0179] FIG. 1n, composed of three parts: case (A), case (B), and case (C), comprises prior art schematic drawings of megaphones and a gramophone, each supplied by a horn;

[0180] FIG. 1L is a prior art schematic drawing of the external ear;

[0181] FIG. 2, composed of four parts: Case (A), Case (Cascade), Case (B), and Case (C), comprises schematic illustrations of sound boosters where: Case (A) is a horn for a gramophone, Case (Cascade) is a brokenly-cascaded waveguiding sound-booster, Case (B) is a phonendoscope, and Case (C) is a sound booster ergonomically adapted to a human's ear canal;

[0182] FIG. 3, composed of two parts: Case (A) and Case (B), comprises schematic illustrations of sound suppressers where: Case (A) is a sound-silencer and case (B) is a brokenly-cascaded in-line arranged sound-silencers of equal inlet and outlet cross-sectional areas.

[0183] All the above and other characteristics and advantages of the invention will be further understood through the following illustrative and non-limitative description of preferred embodiments thereof.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0184] The principles and operation of a method and an apparatus according to the present invention may be better understood with reference to the drawings and the accompanying description, it being understood that these drawings are given for illustrative purposes only and are not meant to be limiting. The DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS is divided into two paragraphs: “Conceptual Idea” and “Embodiments”, each having sub-paragraphs.

Conceptual Idea

Preface And Prerequisites

[0185] The inventor points out the facts that: [0186] sound, as a complicated motion of fluid, comprises a headway conveying motion of a tiny portion of fluid characterizing moving changes in mass density which is associated with the sound loudness, wherein the density changes move with the conveying velocity u.sub.convey that is the same as the velocity of sound u.sub.sound in the fluid, i.e. the density changes move with a high M-velocity higher than the specific M-velocity M.sub.*=√{square root over ((γ− 1)/γ)}. If so, when the sound propagates within a shaped tunnel, the conveying component of the complicated motion of sound is subjected to the de Laval effect. On the other hand, as described hereinabove in THE BACKGROUND OF THE INVENTION referring to prior art FIGS. 1e, 1f, and 1g, the de Laval effect can be optimized to become enhanced by suppression of turbulences and Mach waves origination and providing for an acceleration of a fluid flow at the expense of the fluid heat in the wide sense (i.e. including both the warmth and the energy of concomitant turbulence); [0187] Considering the sound entering into and propagating within the exponentially-divergent horn 1n.C1 of gramophone 1n.C (prior art FIG. 1n), the headway conveying motion of the fluid tiny portion is such that the fluid tiny portion has the conveying M-velocity of 1 Mach at the entrance and further it is subjected to the exponential divergence but not to an optimized divergence which would be happened if the fluid tiny portion was leaking within the divergent exhaust tailpipe 614 of the convergent-divergent nozzle 610 (prior art FIG. 1e), thereby, the primary functionality of the used exponentially-divergent nozzle 1n.C1 can be improved if to use a specifically chosen portion of the convergent-divergent nozzle 610 shown in prior art FIG. 1f to accelerate the conveying component of the complicated motion of sound; and [0188] Considering the sound entering into and propagating within the external ear 1L.0 (prior art FIG. 1L): [0189] on the one hand, the primary set of conditions satisfied for the shape of external ear 1L.1 is as follows: [0190] the factor F.sub.12≈5.5 is much greater than the ratio of 1 Mach to the specific M-velocity, i.e. F.sub.12>1/M.sub.*, [0191] F.sub.32>1, [0192] F.sub.34>F.sub.32, [0193] F.sub.14>1, and [0194] F.sub.54>1/M.sub.*; [0195] and [0196] on the other hand, the set of conditions can be satisfied when implementing a nozzle, which is similar to the two-stage convergent-divergent nozzle 690 shown in prior art FIG. 1g but further configured to satisfy the mentioned set of conditions as well as further restricting conditions providing for a laminar motion of the conveying component of the complicated motion of sound.

Thereby,

[0197] On the one hand, the external ear, as shaped to provide the mentioned set of satisfied conditions, when considered as a two-stage convergent-divergent nozzle applied to the conveying component of the complicated motion of sound, functions as a nozzle capable of two-stage de Laval effect action to accelerate the conveying component of complicated motion of fluid sound, and [0198] On the other hand, an elaborated two-stage convergent-divergent nozzle can be optimized to provide both laminarity and acceleration of the conveying component of the complicated motion of sound, wherein, when the accelerated conveying component of the complicated motion of sound becomes a motion in open space out of the nozzle, it reverts to the conveying motion with the velocity of sound in the open space thereby transforming the acquired kinetic energy of headway motion into the energy of sound characterized by increased amplitude of mass density oscillations, in turn, manifested as sound loudness boosting.

Essence of Concept: Use of Optimal Convergent-Divergent Jet-Nozzle

[0199] The primary idea of the present invention is to adapt the enhanced de Laval effect either for sound loudness boosting or, vice-versa, for suppression of sound loudness. Namely, the adaptation is such that either: [0200] an optimized either divergent or two-stage convergent-divergent acoustic nozzle would play the role of an enhanced acoustic waveguide capable of: [0201] reducing a turbulent component of fluid motion accompanying the acoustic waves and causing dissipation of a propagating sound; and [0202] amplifying the intensity of acoustic waves at the expense of both the heat energy and the turbulence of fluid and so to boost the loudness of sound; or, alternatively, [0203] an optimized convergent-divergent acoustic nozzle would play the role of an enhanced sound-silencer capable of suppressing a waveguide-effect manifested as dissipating the wave power of propagating acoustic waves into the fluid heat.

EMBODIMENTS

[0204] FIG. 2, composed of four parts: Case (A), Case (Cascade), Case (B), and Case (C), illustrates modifications of a passive device having no moving parts designed in accordance with the principles of the present invention for boosting the sound loudness.

Optimized Horn for Gramophone

[0205] FIG. 2 Case (A) shows schematically an acoustic nozzle 2.A embodied as a divergent horn comprising a shaped through-hole tunnel having a divergent sectional profile. The divergent horn 2.A, the geometrical configuration of which is designed in accordance with principles of the present invention, is submerged in a molecular fluid (for the sake of concretization and without loss of generality, the molecular fluid is air) and exposed to a portion of sound 2.A0 launched by a source of acoustic waves 2.A10. The portion of sound 2.A0: [0206] enters an open sound-inlet 2.A1 having a cross-sectional area A.sub.IN, [0207] propagates within the divergent horn 2.A, [0208] reaches the open sound-outlet 2.A2 having a cross-sectional area A.sub.OU, [0209] becomes launched from the open sound-outlet 2.A2, where, in the open space, is detected by a set of detectors 2.A30 of acoustic waves.

[0210] The specific conveying motion of the air density is interpreted as composed of two complementary alternating headway movements of positive and negative changes in air density, wherein both alternating headway movements are in the same direction (that is the direction of sound propagation) and, when the headway movements are in the open space, with the M-velocity of 1 Mach. When the sound portion 2.A0 propagates within the divergent horn 2.A, the specific conveying motion of the fluid tiny portion associated with the sound is subjected to the influence of bordering walls of the shaped through-hole tunnel 2.A.

[0211] The cross-sectional area of the shaped through-hole tunnel 2.A varies along the divergent horn 2.A's length in accordance with the equation Eq. (1.a) wherein there is taken into account the specific boundary condition at the sound-inlet where the M-velocity of the mentioned fluid tiny portion must be equal to 1 Mach. Thus, to provide for that the divergent horn 3.A functions as an enhanced sound-booster, the geometrical configuration of the shaped through-hole tunnel 2.A is characterized by a varying cross-sectional area profile function A.sub.HORN(x) of x-coordinates defined as increasing in a direction of sound propagation, wherein A.sub.HORN(x) is expressed as follows:

[00014]$\begin{array}{cc}{A}_{HORN}\left(x\right)=\frac{A_{\mathrm{IN}}}{M_{HORN}\left(x\right)}{\left(\frac{2+{\gamma \left(M_{HORN}\left(x\right)\right)}^2}{2+\gamma }\right)}^{\frac{\gamma +1}{2\left(\gamma -1\right)}},x_a<x<x_b,& \mathrm{Eq}.\left(2.1\right)\end{array}$

where γ is an adiabatic compressibility parameter of the fluid, x.sub.a and x.sub.b are x-coordinates of the open sound-inlet 2.A1 and open sound-outlet 2.A2, correspondingly, and M.sub.HORN(x) is a monotonically-increasing gradually-smooth function of x representing an M-velocity profile of the fluid tiny portion moving within and through the divergent horn 2.A.
The equation Eq. (2.1) as the equation of continuity in an adiabatic process determines such a cross-sectional area profile function A.sub.HORN(x) that triggers the enhanced de Laval jet-effect applied to the fluid tiny portion, associated with the acoustic wave (or the audible sound) entering the sound-inlet 2.A1 with the M-velocity of 1 Mach, higher than the specific M-velocity. The enhanced de Laval jet-effect, in particular, results in extra-acceleration of the laminar motion of the positive and negative changes in fluid density within the divergent horn 2.A at the expense of the fluid heat, understood in the wide sense including the concomitant turbulence inherently accompanying the acoustic wave.
Thus, the stages of the sound portion 2.A0 are as follows: [0212] The sound portion 2.A0 enters the open sound-inlet 2.A1 with the conveying velocity u.sub.convey corresponding to the M-velocity of 1 Mach; it is the velocity of sound u.sub.sound when the sound is propagating in open space; then [0213] Within the divergent horn 2.A, the specific headway conveying motion of the fluid tiny portion becomes extra-accelerated due to the enhanced de Laval jet-effect; and then [0214] When the propagating sound, after crossing the open sound-outlet 2.A2, reaches the open space behind the open sound-outlet 2.A2 and becomes the launched sound beam 2.A3, the conveying M-velocity reverts back to 1 Mach corresponding to the velocity of sound u.sub.sound in the open space, wherein the acquired kinetic energy of the extra-accelerated specific headway conveying motion of the fluid tiny portion becomes transformed into the acquired wave power of the launched sound 2.A3 that, in turn, is manifested as the sound loudness boosting; namely, the integrated SPL of the launched sound 2.A3 is higher than the origin SPL of the entering sound portion 2.A0. Thus, the divergent horn 2.A is a waveguide that conveys the portion of sound 2.A0 generated by a source of sound 2.A10 to the set of sound detectors 2.A30 and provides for a high intensity of the conveyed sound beam 2.A3, higher than the intensity of the entering sound portion 2.A0. A feature of the embodiment 2.A of the divergent horn waveguide sound-booster is that the cross-sectional area A.sub.OU of the open sound-outlet 2.A2 is greater than the cross-sectional area A.sub.IN of the sound-inlet 2.A1; the higher the ratio A.sub.OU/A.sub.IN, the greater the increase in the acquired SPL of the sound subjected to the action of the divergent horn waveguide sound-booster 2.A.

[0215] In view of the foregoing description of the sub-paragraph “Optimized Horn For Gramophone” referring to FIG. 2 Case (A), it will be evident for a person who has studied the invention that: [0216] on the one hand, the divergent horn 2.A is an optimal sound loudness booster, capable of conveying, widening, and boosting the entered sound beam 2.A0; and [0217] on the other hand, if a waveguiding to a relatively small detector of sound 2.A31 is required, a relatively enormous-huge sound-outlet is undesired.

Cascade of Optimized Horns

[0218] FIG. 2 Case (Cascade) shows schematically an embodiment 2.A40 performing a brokenly-cascaded waveguiding sound-booster constructed according to the principles of the present invention. The embodiment 2.A40 comprises a cascade of an in-line arranged multiplicity of N relatively-short slightly-divergent horns as acoustic nozzles (here, for the sake of simplicity and without loss of generality, N=3 relatively-short slightly-divergent horns are shown only): 2.A41, 2.A42, and 2.A43. The N relatively-short slightly-divergent horns: 2.A41, 2.A42, and 2.A43, denoted by the index n varying from 1 to N, have open sound-inlets: 2.A51, 2.A52, and 2.A53, having sound-inlets' cross-sectional areas A.sub.IN,n, n=1, 2, . . . , N, and open sound-outlets: 2.A61, 2.A62, and 2.A63, having sound-inlets' cross-sectional areas A.sub.OU,n, n=1, 2, . . . , N, correspondingly. There are certain intervals of open space 2.A71 and 2.A72 between intermediate open sound-inlets 2.A52 to 2.A53 and intermediate open sound-outlets 2.A61 to 2.A62, correspondingly, within the embodiment 2.A40. Thereby, the cascade 2.A40 of the in-line arranged multiplicity of N relatively-short slightly-divergent horns: 2.A41, 2.A42, and 2.A43, arranged with intervals of open space and considered as a whole, performs a broken through-hole tunnel-waveguide 2.A40, submerged in the molecular fluid and being exposed to a sound beam 2.A00 generated by a source of sound 2.A11. Each n-th of the N relatively-short slightly-divergent horns is recognized by a varying cross-sectional area characterized by a slightly-divergent cross-sectional area profile function A.sub.n(x), n=1, 2, . . . , N, such that the embodiment 2.A40 as a whole is recognized by the geometrical configuration of the through-hole tunnel-waveguide broken with intervals of open space, wherein the geometrical configuration has a varying cross-sectional area characterized by a cross-sectional area profile function A.sub.BROKEN(x) specified as a piecewise-broken-with-intervals piecewise-divergent profile function of x comprising the N slightly-divergent portions A.sub.n(x). Each n-th of the N slightly-divergent portions A.sub.n(x) is expressed as

[00015]$\begin{array}{cc}{A}_n\left(x\right)=\frac{A_{*n}}{M_n\left(x\right)}{\left(\frac{\gamma -1}{\gamma }\right)}^{\frac{1}{2}}{\left(\frac{2+{\gamma \left(M_n\left(x\right)\right)}^2}{\gamma +1}\right)}^{\frac{\gamma +1}{2\left(\gamma -1\right)}},\begin{array}{c}{x}_{a,n}<x<x_{b,n}\\ n=1,2,\mathrm{.Math.},N\end{array},& \mathrm{Eq}.\left(2.2\right)\end{array}$

where the index n varies from 1 to N, x.sub.a,n and x.sub.b,n are x-coordinates of the open sound-inlet and open sound-outlet, correspondingly, of the n-th divergent horn, γ is an adiabatic compressibility parameter of the fluid, and M.sub.n(x) is an n-th monotonically-increasing gradually-smooth function of x representing an M-velocity profile of the fluid tiny portion moving within and through the divergent horn.

[0219] The N equations Eq. (2.2), as the equations of continuity in an adiabatic process applied to the headway motion of the fluid tiny portions entering each of the sound-inlets 2.A51, 2.A52, and 2.A53 with the M-velocity of 1 Mach, higher than the specific M-velocity M.sub.*=√{square root over ((γ− 1)/γ)}, altogether provide for a substantially laminar motion of the positive and negative changes in air density within each of the relatively-short slightly-divergent horns: 2.A41, 2.A42, and 2.A43 due to the enhanced de Laval jet-effect. Thus, the sound beam 2.A00: [0220] enters the sound-inlet 2.A51 of the first relatively-short slightly-divergent horn 2.A41, where, immediately after entering, the laminar motion of the positive and negative changes in air density becomes accelerated as a headway motion of fluid moving within a divergent pipe with the high M-velocity of 1 Mach, higher than the specific M-velocity M.sub.*=√{square root over ((γ− 1)/γ)}; [0221] further propagates within and along the broken through-hole tunnel-waveguide 2.A40, [0222] sequentially reaches the intermediate intervals 2.A71 to 2.A72 where the propagating sound beam portions 2.A01 to 2.A02, correspondingly, become in open spaces and so become characterized with the conveying motion with the M-velocity of 1 Mach; wherein the intermediate intervals of the open spaces 2.A71 to 2.A72 can be chosen as extremely short in the direction of the sound propagation because the minor mass of the fluid tiny portion associated with the propagating sound is practically inertialess, and so, the open space M-velocity of sound, i.e. 1 Mach, is reachable in the open space almost immediately behind each of the intermediate open sound-outlets: 2.A61 to 2.A62; such that: [0223] on the one hand, when the propagating sound crosses the intervals of open space 2.A71 to 2.A72, the sequentially acquired portions of the kinetic energy of the accelerated specific headway conveying motion of the fluid tiny portion become transformed into the acquired wave power of the propagating sound beam portions 2.A01 to 2.A02, correspondingly, and [0224] on the other hand, the propagating sound beam portions 2.A01 to 2.A02 enter the open sound-inlets 2.A52 to 2.A53, correspondingly, with the M-velocity of 1 Mach, thereby always satisfying the condition of the entrance the open sound-inlet of a next relatively-short slightly-divergent horn with the M-velocity of 1 Mach; [0225] reaches the sound-outlet 2.A63 of the last relatively-short slightly-divergent horn 2.A43, and [0226] becomes the finally launched sound beam 2.A03 in open space behind the last sound-outlet 2.A63, where the cumulatively acquired portion of the kinetic energy of the accelerated specific headway conveying motion of the fluid tiny portion becomes transformed into the acquired wave power of the finally launched sound beam 2.A03.

[0227] In view of the foregoing description of the sub-paragraphs “Cascade Of Optimized Horns” referring to FIG. 2 Case (Cascade), it will be evident for a person who has studied the invention that: [0228] the cascade of the in-line arranged multiplicity of N relatively-short slightly-divergent horns 2.A40, arranged with intervals of open space and considered as a whole, is an optimized sound loudness booster, capable of conveying and amplifying the entered sound beam 2.A00; and [0229] if a waveguiding to a relatively small detector of sound 2.A31 is required, the use of the broken through-hole tunnel-waveguide 2.A40 is preferred to provide a slightly widened and substantially amplified resulting sound beam 2.A03.

Phonendoscope and Sound-Booster

[0230] FIG. 2 Cases (B) and (C) are schematic illustrations of two-stage convergent-divergent acoustic nozzles 2.B and 2.C, destined for amplifying the intensity of an entering portion of sound 2.B0 and 2.C0, correspondingly. The enhanced phonendoscope 2.B and sound booster 2.C, both constructed according to the principles of the present invention, comprise common configurational features as follows: [0231] the two-stage convergent-divergent acoustic nozzle playing the role of the sound-booster to be used as a phonendoscope having a configured corpus, 2.B1 or 2.C1, comprising a through-hole tunnel-waveguide, 2.B2 or 2.C2, wherein: [0232] a sound-inlet, 2.B5 or 2.C5, of a first convergent-divergent fragment has a cross-sectional area A.sub.IN, [0233] a sound-outlet, 2.B6 or 2.C6, of a second convergent-divergent fragment has a cross-sectional area A.sub.OU, and [0234] shaped portions of a varying cross-section recognized by: [0235] a convergent funnel, 2.B41 or 2.C41, [0236] the first narrow throat, 2.B42 or 2.C42, having a local minimal cross-sectional area A.sub.TH1, [0237] a widened cavity, 2.B43 or 2.C43, having a local maximal cross-sectional area A.sub.CA, [0238] the second narrow throat, 2.B44 or 2.C44, having the local minimal cross-sectional area A.sub.TH2, wherein, theoretically, an optimal A.sub.TH2 is equal to A.sub.TH1, and in practice implementation, A.sub.TH2 is at most equal to A.sub.TH1, and [0239] divergent funnel, 2.B45 or 2.C45, [0240] and [0241] the cross-sectional area profile smooth function A(x) is composed of sequentially concatenated cross-sectional area profile functions A.sub.1(x), A.sub.CA(x), and A.sub.2(x), wherein A.sub.1(x) and A.sub.2(x) are cross-sectional area profile functions of the first and second convergent-divergent fragments, which provide for the de Laval jet-effects, decelerating and accelerating the fluid tiny portion associated with the propagating sound, correspondingly, and A.sub.CA(x) is cross-sectional area profile function of the widened cavity providing for the enhanced Venturi effect while a gradually-smooth function M.sub.CA(x) of x, representing an M-velocity profile of the fluid tiny portion associated with the propagating sound and moving in the widened cavity between the first and second convergent-divergent fragments, remains lower than the specific M-velocity M.sub.*=√{square root over ((γ− 1)/γ)}; the cross-sectional area profile functions A.sub.1(x) and A.sub.2 (x) are given by the equations expressed as:

[00016]$\begin{array}{cc}\{\begin{array}{cc}{A}_1\left(x\right)=\frac{A_{TH1}}{M_1\left(x\right)}{\left(\frac{\gamma -1}{\gamma }\right)}^{\frac{1}{2}}{\left(\frac{2+{\gamma \left(M_1\left(x\right)\right)}^2}{\gamma +1}\right)}^{\frac{\gamma +1}{2\left(\gamma -1\right)}},& x_{a,1}<x<x_{b,1}\\ A_2\left(x\right)=\frac{A_{TH2}}{M_2\left(x\right)}{\left(\frac{\gamma -1}{\gamma }\right)}^{\frac{1}{2}}{\left(\frac{2+{\gamma \left(M_2\left(x\right)\right)}^2}{\gamma +1}\right)}^{\frac{\gamma +1}{2\left(\gamma -1\right)}},& x_{a,2}<x<x_{b,2}\end{array},& \mathrm{Eq}.\left(2.3\right)\end{array}$ [0242] where: [0243] γ is an adiabatic compressibility parameter of the fluid, [0244] x.sub.a,1 and x.sub.b,1 are x-coordinates of the open sound-inlet and open sound-outlet, correspondingly, of the first convergent-divergent fragment, [0245] x.sub.a,2 and x.sub.b,2 are x-coordinates of the open sound-inlet and open sound-outlet, correspondingly, of the second convergent-divergent fragment, [0246] M.sub.1(x) is a monotonically-decreasing gradually-smooth function of x, [0247] M.sub.2(x) is a monotonically-increasing gradually-smooth function of x, [0248] wherein M.sub.1(x), M.sub.CA(x), and M.sub.2(x) are sequentially-concatenated to form a gradually-smooth function M(x) of x, representing an M-velocity profile of the fluid tiny portion moving within and through the two-stage convergent-divergent acoustic nozzle's through-hole tunnel-waveguide, 2.B2 or 2.C2; and [0249] A.sub.TH1 and A.sub.TH2 are local minimal cross-sectional areas of narrow throats of the first and second convergent-divergent fragments, correspondingly; [0250] wherein the satisfied conditions are as follows: [0251] (a) the boundary condition at the sound-inlet

[00017]$\begin{array}{cc}\frac{A_{\mathrm{IN}}}{A_{TH1}}\ge \sqrt{\left(\frac{\gamma -1}{\gamma }\right){\left(\frac{2+\gamma }{\gamma +1}\right)}^{\frac{\gamma +1}{\left(\gamma -1\right)}}};& \mathrm{Eq}.\left(23a\right)\end{array}$ [0252] (b) the condition of presence of a widened cavity after the first convergent-divergent fragment

[00018]$\begin{array}{cc}{A}_{CA}/A_{TH1}>1;& \mathrm{Eq}.\left(2.3b\right)\end{array}$ [0253] (c) the condition of presence of a widened cavity before the second convergent-divergent fragment

[00019]$\begin{array}{cc}{A}_{CA}/A_{TH2}>1;& \mathrm{Eq}.\left(2.3c\right)\end{array}$ [0254] (d) the condition of proportion between cross-sectional areas of the two narrow throats of the two convergent-divergent fragments,

[00020]$\begin{array}{cc}{A}_{TH1}/A_{TH2}\ge 1,& \mathrm{Eq}.\left(2.3d\right)\end{array}$ [0255] thereby providing for an acceleration of the fluid tiny portion moving within and through the second convergent-divergent fragment of the two-stage convergent-divergent acoustic nozzle's through-hole tunnel-waveguide, 2.B2 or 2.C2, such, to cross the second narrow throat, 2.B44 or 2.C44, with the specific M-velocity M.sub.*=√{square root over ((γ− 1)/γ)}; and [0256] (e) the boundary condition at the sound-inlet,

[00021]$\begin{array}{cc}\frac{A_{OU}}{A_{TH2}}>\sqrt{\left(\frac{\gamma -1}{\gamma }\right){\left(\frac{2+\gamma }{\gamma +1}\right)}^{\frac{\gamma +1}{\left(\gamma -1\right)}}};.& \mathrm{Eq}.\left(2.3e\right)\end{array}$

[0257] While the two-stage convergent-divergent acoustic nozzle 2.B is configured to be used as an enhanced phonendoscope 2.B, the two-stage convergent-divergent acoustic nozzle 2.C is configured to have a corpus 2.C1 ergonomically adapted to a human's ear canal, thereby, allowing to be used as a sound booster 2.C ergonomically adapted to a human's ear 2.EAR.

[0258] The sound, 2.B0 or 2.C0, when entering the open sound-inlet, 2.B5 or 2.C5, becomes subjected to the action of the optimized convergent-divergent tunnel, 2.B2 or 2.C2, elaborated according to the equation Eq. (2.3) accompanied by the specific conditions Eqs. (2.3a) to (2.3e) interrelating the cross-sectional areas A.sub.IN, A.sub.OU, A.sub.TH1, A.sub.CA, and A.sub.TH2 such that, [0259] first, when the sound, 2.B0 or 2.C0, propagates through a convergent funnel, 2.B41 or 2.C41, the sound intensity becomes: [0260] on the one hand, decreased because the fluid tiny portion, being conveyed with the velocity of sound, becomes subjected to retarding due to the de Laval retarding-effect applied to the fluid tiny portion moving with the high velocity, higher than the specific M-velocity, and [0261] on the other hand, increased due to: [0262] superposition of spatially distributed portions of sound becoming concentrated and joint in-phase, thereby, resulting in constructive interference, [0263] transformation of the internal heat energy of fluid into the acquired power of sound, as a manifestation of the Venturi effect, applied to longitudinal oscillation motion with the particle velocity, and [0264] suppression of concomitant turbulence, power of which, in the final analysis, becomes transformed into the acquired power of sound, as a phenomenon accompanying the Venturi effect applied to longitudinal oscillation motion with the particle velocity; [0265] second, the condition Eq. (2.3a) is satisfied, and so the motion of the fluid tiny portion, when the sound propagates through the first narrow throat, 2.B42 or 2.C42, is decelerated and the sound intensity predetermined by the conveying velocity U.sub.convey is gradually decreasing due to the de Laval retarding-effect applied to the fluid tiny portion; wherein the local conveying M-velocity is equal to M.sub.*=√{square root over ((γ− 1)/γ)} when the fluid tiny portion crosses the narrowest cross-section within the first throat, 2.B42 or 2.C42; [0266] third, the condition: A.sub.IN/A.sub.TH1>1 is satisfied and so, when the sound propagates through the first narrow throat 2.C42, the sound intensity predetermined by the particle velocity u.sub.particle is gradually increasing due to the Venturi effect applied to the slow-moving mass of fluid tiny portion of the fluid; [0267] fourth, the condition: A.sub.CA/A.sub.TH1>1 Eq. (2.3b) is satisfied and so, when the sound propagates through the widened cavity, 2.B43 or 2.C43, the local conveying M-velocity becomes lower than the specific M-velocity M.sub.*, due to the enhanced de Laval retarding-effect; [0268] fifth the conditions:

[00022]$\begin{array}{cc}{A}_{CA}/A_{TH2}>1\mathrm{and}& \mathrm{Eq}.\left(2.3c\right)\\ A_{TH1}/A_{TH2}\ge 1,& \mathrm{Eq}.\left(2.3d\right)\end{array}$ [0269] both are satisfied and so, when the sound propagates through the second narrow throat, 2.B44 or 2.C44, the local conveying M-velocity reaches the specific M-velocity M., due to the enhanced de Laval jet-effect; and [0270] sixth, the conditions:

[00023]$\begin{array}{cc}{A}_{CA}/A_{TH2}>1\mathrm{and}& \mathrm{Eq}.\left(2.3c\right)\\ \frac{A_{OU}}{A_{TH2}}>\mapsto \sqrt{\left(\frac{\gamma -1}{\gamma }\right){\left(\frac{2+\gamma }{\gamma +1}\right)}^{\frac{\gamma +1}{\left(\gamma -1\right)}}}& \mathrm{Eq}.\left(2.3e\right)\end{array}$ [0271] both are satisfied and so, when the sound propagates further through divergent funnel, 2.B45 or 2.C45, the sound intensity becomes increased because the fluid tiny portion associated with the propagating sound, conveying with the varying velocity, becomes subjected to extra-acceleration due to the enhanced de Laval jet-effect applied to the fluid tiny portion moving with the high velocity, higher than the specific M-velocity and optimized to suppress turbulent component of the complicated movement of fluid when conveying the sound.

[0272] In view of the foregoing description of the sub-paragraphs “Optimized Horn For Gramophone” referring to FIG. 2 Case (A), “Cascade Of Optimized Horns” referring to FIG. 2 Case (Cascading), and “Phonendoscope and Sound Booster” referring to FIG. 2 Cases (B) and (C) compared with the description of sub-paragraphs: “Sound as Complicated Movement in Molecular Fluid” referring to prior art FIG. 1n and “External Ear” referring to prior art FIG. 1L, it becomes evident to a person who has studied the present patent application that, conceptually: [0273] The external ear 1L.0 (FIG. 1L) functions as the described passive sound booster 2.C, but not optimized for suppression of concomitant turbulences according to the equation Eq. (2.3) accompanied by the associated requirements to the cross-sectional areas A.sub.IN, A.sub.TH1, A.sub.CA, A.sub.TH2, and A.sub.OU yet; [0274] An optimized two-stage convergent-divergent acoustic nozzle, optimized for providing laminar motion of the fluid tiny portion according to the equation Eq. (2.3) and accompanied conditions Eqs. (2.3a) to (2.3e), can be adapted to a diversity of applications as a wave-guiding and sound-amplifying nozzle for detectors or launchers of sound, for instance: [0275] the optimized two-stage convergent-divergent acoustic nozzle 2.B can be utilized as a phonendoscope; and [0276] the optimized two-stage convergent-divergent acoustic nozzle 2.C can be ergonomically-adapted to a human's ear canal and play a role of a passive sound-booster utilized for amplifying the loudness of a portion of ambient sound; [0277] An optimized divergent horn, optimized for widening a front of sound beam accompanied by suppression of concomitant turbulences according to the equation Eq. (2.1), can be scaled to play the role of an enhanced generalized gramophone utilized for boosting a sound launched by a source of acoustic waves; and [0278] An acoustic waveguide representing a cascade of the in-line arranged multiplicity of N relatively-short slightly-divergent horns, arranged with intervals of open space and considered as a whole, wherein the cross-sectional area of each of the of N relatively-short slightly-divergent horns is optimized and adapted to launch a sound beam of a certain sound-outlet cross-sectional shape and area according to a set of N equations Eq. (2.2) to provide conveying and boosting a sound at the expense of the heat of fluid and concomitant turbulences.

Sound-Silencer

[0279] FIG. 3, composed of two parts: Case (A) and Case (B), illustrates modifications of an enhanced sound-silencer. The modifications are passive devices having no moving parts designed in accordance with the principles of the present invention for suppression of sound loudness.

Optimized Sound Dissipator

[0280] FIG. 3 Cases (A) is a schematic illustration of a convergent-divergent acoustic nozzle 3.A destined for reducing the intensity of an entering portion of sound 3.A0 to function as an enhanced sound-silencer. The convergent-divergent acoustic nozzle 3.A comprises a shaped through-hole tunnel having a convergent-divergent sectional profile. The convergent-divergent acoustic nozzle 3.A, the geometrical configuration of which is designed in accordance with principles of the present invention, is submerged in a molecular fluid (for the sake of concretization and without loss of generality, the molecular fluid is air) and exposed to a portion of sound 3.A0 launched by a source of acoustic waves 3.A10. The portion of sound 3.A0: [0281] enters an open sound-inlet 3.A1 having a cross-sectional area A.sub.IN, [0282] propagates within the convergent-divergent acoustic nozzle 3.A through a narrow throat 3.A4 crossing a minimal cross-sectional area A.sub.TH at a critical condition point 3.A41, [0283] reaches the open sound-outlet 3.A2 having a cross-sectional area A.sub.OU, [0284] becomes launched from the open sound-outlet 3.A2, where, in the open space, is detected by a set of acoustic wave detectors 3.A30.
Again, the specific conveying motion of the air density is interpreted as composed of two complementary alternating headway movements of positive and negative changes in air density, wherein both alternating headway movements are in the same direction (that is the direction of sound propagation) and, when the headway movements are in the open space, with the M-velocity of 1 Mach. When the sound portion 3.A0 propagates within the convergent-divergent acoustic nozzle 3.A, the specific conveying motion of the air density is subjected to the influence of bordering walls of the shaped through-hole tunnel 3.A. To provide for that the convergent-divergent acoustic nozzle 3.A functions as an enhanced sound-silencer destined for reducing the intensity of the entering portion of sound 3.A0, the geometrical configuration of the shaped through-hole tunnel 3.A is characterized by a varying cross-sectional area profile function A.sub.SILENCER (x) of x expressed as:

[00024]$\begin{array}{cc}{A}_{\mathrm{SILENCER}}\left(x\right)=\frac{A_{TH}}{M_{\mathrm{SILENCER}}\left(x\right)}{\left(\frac{\gamma -1}{\gamma }\right)}^{\frac{1}{2}}{\left(\frac{2+{\gamma \left(M_{\mathrm{SILENCER}}\left(x\right)\right)}^2}{\gamma +1}\right)}^{\frac{\gamma +1}{2\left(\gamma -1\right)}},& \mathrm{Eq}.\left(3.1\right)\end{array}$

where γ is an adiabatic compressibility parameter of the fluid and M.sub.SILENCER(x) is a monotonically-decreasing gradually-smooth function of x representing an M-velocity profile of the fluid tiny portion moving within and through the convergent-divergent acoustic nozzle 3.A, wherein the ratio of the cross-sectional area A.sub.IN of the nozzle's open sound-inlet 2.A1 to the local minimal cross-sectional area A.sub.TH satisfies to the condition:

[00025]$\begin{array}{cc}\frac{A_{\mathrm{IN}}}{A_{TH}}\ge \sqrt{\left(\frac{\gamma -1}{\gamma }\right){\left(\frac{2+\gamma }{\gamma +1}\right)}^{\frac{\gamma +1}{\left(\gamma -1\right)}}}.& \mathrm{Eq}.\left(3.1a\right)\end{array}$

The condition Eq. (3.1a) provides for triggering the enhanced de Laval retarding-effect applied to the fluid tiny portion entering the sound-inlet 3.A1 with the M-velocity of 1 Mach, higher than the specific M-velocity. The enhanced de Laval retarding-effect, in particular, results in extra-deceleration of the laminar motion of the positive and negative changes in air density within the convergent-divergent acoustic nozzle 3.A resulting in dissipation of the acoustic wave power into the air heat understood in the direct sense. Thus, the stages of the sound portion 3.A0 are as follows: [0285] The sound portion 3.A0 enters the open sound-inlet 3.A1 with the conveying velocity u.sub.convey corresponding to the M-velocity of 1 Mach; it is the velocity of sound u.sub.sound when the sound is propagating in open space; then [0286] Within the convergent-divergent acoustic nozzle 3.A, the specific headway conveying motion of the fluid tiny portion becomes extra-decelerated due to the enhanced de Laval retarding-effect; and then [0287] When the propagating sound reaches the open space behind the open sound-outlet 3.A2 and becomes the launched sound beam 3.A3, the conveying M-velocity reverts back to 1 Mach corresponding to the velocity of sound u.sub.sound in the open space, wherein the dissipated and thereby reduced kinetic energy of the decelerated specific headway conveying motion of the fluid tiny portion becomes rebuilt at the expense of the brought acoustic wave power of the launched sound 3.A3 that is manifested as the sound silencing: i.e. the integrated SPL of the launched sound 3.A3 which is registered by a set of sound detectors 3.A30 is lower than the origin SPL of the entering sound portion 3.A0 because the energy portion of the entering sound portion 3.A0 is unrecoverably dissipated into the heat of fluid due to the enhanced de Laval retarding effect.
Thereby, the convergent-divergent acoustic nozzle 3.A is an optimized sound dissipator capable of transforming the acoustic wave power into the heat energy of fluid and provides for the launched sound beam 3.A3 of decreased intensity, decreased becoming lower than the intensity of the entering sound portion 3.A0. A further feature of the embodiment of the sound-silencer 3.A is that the greater the ratio A.sub.OU/A.sub.IN, the lower the integral SPL of the launched sound beam 3.A3.

[0288] In view of the foregoing description of the sub-paragraph “Optimized Sound Dissipator” referring to FIG. 3 Case (A), it will be evident for a person who has studied the invention that: [0289] on the one hand, the convergent-divergent acoustic nozzle 3.A is an optimal sound-silencer, capable of dissipating the wave power of the entered sound beam 3.A0 into the heat of fluid; and [0290] on the other hand, if it is required to dissipate a sound of a relatively wide front, the use of a sound-silencer having a relatively small sound-inlet and a relatively enormous-huge sound-outlet is not suitable.

Cascade Of Optimized Sound-Silencers

[0291] FIG. 3 Case (B) shows schematically an embodiment 3.B40 constructed according to the principles of the present invention. The embodiment 3.B40 comprises a cascade of an in-line arranged multiplicity of N relatively-short slightly-convergent-divergent acoustic nozzles (here, for the sake of simplicity and without loss of generality, N=3 relatively-short slightly-convergent-divergent acoustic nozzles are shown only): 3.B41, 3.B42, and 3.B43. The N relatively-short slightly-convergent-divergent acoustic nozzles: 3.B41, 3.B42, and 3.B43, have open sound-inlets: 3.B51, 3.B52, and 3.B53, narrow throats: 3.B81, 3.B82, and 3.B83, recognized by minimal cross-sectional areas at positions: 3.B91, 3.B92, and 3.B93, and open sound-outlets: 3.B61, 3.B62, and 3.B63, correspondingly. There are certain intervals of open space 3.B71 and 3.B72 between intermediate open sound-inlets 3.B52 to 3.B53 and intermediate open sound-outlets 3.B61 to 3.B62, correspondingly, within the embodiment 3.B40. Thereby, the cascade 3.B40 of the in-line arranged multiplicity of relatively-short slightly-convergent-divergent acoustic nozzles: 3.B41, 3.B42, and 3.B43, arranged with intervals of open space and considered as a whole, performs a broken through-hole tunnel-waveguide 3.B40, submerged in the molecular fluid and exposed to a sound beam 3.B00 generated by a source of sound 3.B10. The N relatively-short slightly-convergent-divergent acoustic nozzles are denoted by the index n varying from 1 to N; each n-th of the N relatively-short slightly-conevergent-divergent acoustic nozzles is recognized by a varying cross-sectional area characterized by a slightly-convergent-divergent cross-sectional area profile function A.sub.n(x), n=1, 2, . . . , N, such that the embodiment 3.B40 as a whole is recognized by the geometrical configuration of the through-hole tunnel-waveguide broken with intervals of open space, wherein the geometrical configuration has a varying cross-sectional area characterized by a cross-sectional area profile function A.sub.BROKEN(x) specified as a piecewise-broken-with-intervals piecewise-convergent-divergent cross-sectional area profile function of x comprising the N slightly-convergent-divergent portions A.sub.n(x). Each n-th of the N slightly-convergent-divergent portions A.sub.n(x) is expressed as

[00026]$\begin{array}{cc}{A}_n\left(x\right)=\frac{A_{*n}}{M_n\left(x\right)}{\left(\frac{\gamma -1}{\gamma }\right)}^{\frac{1}{2}}{\left(\frac{2+{\gamma \left(M_n\left(x\right)\right)}^2}{\gamma +1}\right)}^{\frac{\gamma +1}{2\left(\gamma -1\right)}},\begin{array}{c}{x}_{a,n}<x<x_{b,n}\\ n=1,2,\mathrm{.Math.},N\end{array},& \mathrm{Eq}.\left(3.2\right)\end{array}$

where the index n varies from 1 to N, x.sub.a,n and x.sub.b,n are x-coordinates of the open sound-inlet and open sound-outlet, correspondingly, of the n-th divergent horn, γ is an adiabatic compressibility parameter of the fluid, M.sub.n(x) is an n-th monotonically-decreasing gradually-smooth function of x representing an M-velocity profile of the fluid tiny portion moving within and through the n-th slightly-convergent-divergent acoustic nozzle, and A.sub.*n is an n-th constant having a sense of the minimal cross-sectional area within the corresponding narrow throat, wherein the constant A.sub.*n is lesser than both a cross-sectional area A.sub.IN,n of the nozzle's sound-inlet 3.A51 and a cross-sectional area A.sub.OU,n of the nozzle's sound-outlet 3.A61, the ratio of the cross-sectional area A.sub.IN,n of the horn's sound-inlet 2.A1 to the constant A.sub.*n satisfies to the condition:

[00027]$\begin{array}{cc}\frac{A_{\mathrm{IN},n}}{A_{*n}}\ge \sqrt{\left(\frac{\gamma -1}{\gamma }\right){\left(\frac{2+\gamma }{\gamma +1}\right)}^{\frac{\gamma +1}{\left(\gamma -1\right)}}},n=1,2,\mathrm{.Math.},N,& \mathrm{Eq}.\left(3.2a\right)\end{array}$

wherein the optimal ratio of the cross-sectional area A.sub.IN,n of the horn's sound-inlet 2.A1 to the constant A.sub.*n satisfies a condition as follows:

[00028]$\begin{array}{cc}\frac{A_{\mathrm{IN},n}}{A_{*n}}=\sqrt{\left(\frac{\gamma -1}{\gamma }\right){\left(\frac{2+\gamma }{\gamma +1}\right)}^{\frac{\gamma +1}{\left(\gamma -1\right)}}},n=1,2,\mathrm{.Math.},N.& \mathrm{Eq}.\left(3.2b\right)\end{array}$

[0292] The conditions: Eq. (3.2) as the equation of continuity in an adiabatic process and Eq. (3.2b) for the optimal ratio A.sub.IN,n/A.sub.*n, both-together provide for a substantially laminar motion of the positive and negative changes in air density within each of the relatively-short slightly-convergent-divergent acoustic nozzles: 3.A41, 3.A42, and 3.A43 due to the enhanced de Laval retarding-effect applied to the moving positive and negative changes in air density, entering the nozzles with the high M-velocity of 1 Mach, higher than the specific M-velocity M.sub.*=√{square root over ((γ− 1)/γ)}. The sound beam 3.A00: [0293] enters the sound-inlet 3.A51 of the first relatively-short slightly-convergent-divergent acoustic nozzle 3.A41, where, [0294] immediately after entering, the laminar motion of the positive and negative changes in air density becomes decelerated as a headway motion of fluid moving within a converging pipe with the high M-velocity of 1 Mach, higher than the specific M-velocity M.sub.*=√{square root over ((γ− 1)/γ)}; [0295] when crossing the position 3.B91, the laminar motion of the positive and negative changes in air density is characterized by the specific M-velocity M (γ− 1)/γ and, [0296] downstream behind the position 3.B91, the laminar motion of the positive and negative changes in air density remains decelerating according to the enhanced de Laval retarding effect, wherein the laminarity of motion is provided by the conditions Eq. (3.2) and Eq. (3.2a); [0297] further propagates within and along the broken through-hole tunnel-waveguide 3.B40; [0298] sequentially reaches the intermediate intervals 3.B71 to 3.B72 where the propagating sound beam portions 3.B01 to 3.B02, correspondingly, become in open spaces and so become characterized with the conveying motion with the M-velocity of 1 Mach; wherein the intermediate intervals 3.B71 to 3.B72 of the open spaces can be chosen as extremely short because the minor mass of the fluid tiny portion associated with the propagating sound is practically inertialess and so, the open space M-velocity of sound, i.e. 1 Mach, is reachable in the open space immediately behind the intermediate open sound-outlets 3.B61 to 3.B62; such that: [0299] on the one hand, the sequentially acquired portions of the kinetic energy of the accelerated specific headway conveying motion of the fluid tiny portion become transformed into the acquired wave power of the propagating sound beam portions 3.B01 to 3.B02, and [0300] on the other hand, the propagating sound beam portions 3.B01 to 3.B02 enter the open sound-inlets 3.B52 and 3.B53 with the M-velocity of 1 Mach, thereby always satisfying the condition of the entrance the open sound-inlet of a next relatively-short slightly-convergent-divergent acoustic nozzle with the M-velocity of 1 Mach; [0301] reaches the sound-outlet 3.B63 of the last relatively-short slightly-convergent-divergent acoustic nozzle 3.B43, and [0302] becomes the finally launched sound beam 3.B03 in open space behind the last sound-outlet 3.B63, where the dissipated portion of the kinetic energy of the extra-decelerated specific headway conveying motion of the fluid tiny portion becomes rebuilt at the expense of the remained after the partial dissipation wave power of the finally launched sound beam 3.B03.

[0303] In view of the foregoing description of the sub-paragraphs “Cascade Of Optimized Sound-Silencers” referring to FIG. 3 Case (B), it will be evident for a person who has studied the invention that: [0304] the cascade of the in-line arranged multiplicity of N relatively-short slightly-convergent-divergent acoustic nozzles 3.B40, arranged with intervals of open space and considered as a whole, is an optimal sound-silencer, capable of dissipating the entered sound beam 3.B00; and [0305] if, from the point of view of a detector of sound 3.B30, sound isolation of the source of sound 3.B10 is required, the use of the broken through-hole tunnel-waveguide 3.B40 is preferred to provide a substantially dissipated resulting sound beam 3.B03.

[0306] In the claims, reference signs are used to refer to examples in the drawings for the purpose of easier understanding and are not intended to be limiting on the monopoly claimed.