Method for influencing an auditory direction perception of a listener and arrangement for implementing the method

Abstract

A method for influencing an auditory direction perception of a listener, and to an arrangement for it the method is disclosed, to provide a solution, by means of which the improvement of the suppression of the auditory localization of a direction of one or more real sources S.sub.1 of a sound projecting audio playback system is achieved in that a localization-masking additionally generated sound entity is provided and is radiated by the real source S.sub.1 with a directional effect in a defined direction.

Claims

1. A method for influencing an auditory direction perception of a listener comprising the steps of: emitting a focused sound bundle by a real source S.sub.1 having a steerable sound radiation pattern with a main lobe and side lobes that generates a directional effect, with sound from at least one of the side lobes reaching the listener as a direct sound component on a direct path between the real source S.sub.1 and the listener and with sound from the main lobe reaching the listener as an indirect sound component on an indirect path after at least one reflection at a sound-reflecting boundary surface from a direction that is different from the direct path, wherein emitting the sound bundle comprises generating a first sound instance of the sound bundle which arrives at the listener on the indirect path later than on the direct path, generating a second sound instance of the sound bundle which arrives at the listener on the indirect path no later than the first sound instance on the direct path and has a sound amplitude equal to or greater than a sound amplitude of both the first and the second sound instance on the direct path.

2. The method according to claim 1, further comprising generating at least one additional sound instance of the sound bundle which arrives at the listener on the indirect path no later than a preceding sound instance on the direct path and has a sound amplitude equal to or greater than a sound amplitude of both the preceding and the additional sound instance on the direct path, and repeating generating additional sound instances until the listener no longer experiences a resultant hearing event from the direction of the direct path.

3. The method according to claim 2, further comprising specifying a point in time for providing the second or the at least one additional sound instance depending on at least one of subjective user settings, room acoustics measurements, model simulations and estimates.

4. The method according to claim 2, further comprising specifying a point in time for providing the second or the at least one additional sound instance depending on psychoacoustic measurements or on electroacoustic measurements.

5. The method according to claim 2, wherein the second or the at least one additional sound instance is provided using envelope manipulation or HRTF (head-related transfer function) filtering.

6. The method according to claim 5, wherein the second or the at least one additional sound instance is provided so as to at least partially overlap in time with the first sound instance or the second sound instance or the at least one additional sound instance on the direct path.

7. The method according to claim to 1, wherein the second sound instance is provided using envelope manipulation or HRTF (head-related transfer function) filtering.

8. The method according to claim 7, wherein the second sound instance is provided so as to at least partially overlap in time with the first sound instance on the direct path.

9. The method according to claim 1, wherein the real source S.sub.1 has a plurality of sound transducers such as speakers, which are arranged side by side or one above the other or in an array side by side and one above the other.

10. The method according to claim 1, wherein the real source S.sub.1 is arranged in a room with sound-reflecting boundaries.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The aforedescribed features and advantages of the present invention can be better understood and evaluated after careful study of the following detailed description of the preferred, non-limiting exemplary embodiments of the invention in conjunction with the accompanying drawings, which show in:

(2) FIG. 1 a schematic diagram of the method for localization masking of a real source in a sound-projecting audio playback system,

(3) FIG. 2: a diagram of a schematic approach for generating a virtual source according to the prior art,

(4) FIG. 3: an illustration of a time-amplitude diagram for a scenario according to FIG. 2,

(5) FIG. 4: a time-amplitude diagram with an additionally generated sound instance according to the invention in an idealized representation,

(6) FIG. 5: in a non-idealized representation, a time-amplitude diagram with a sound instance additionally generated according to the invention, and

(7) FIG. 6: a further schematic diagram of the invention with several additionally generated sound instances.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(8) FIG. 1 shows a schematic diagram of the method for localization masking of a real source in a sound-projecting audio playback system. FIG. 1 also shows the assemblies essential for an arrangement for implementing the method for influencing an auditory direction perception of a listener (7). In particular, a localization masking processor for generating the at least one additionally generated sound instance (13) for localization masking is illustrated. The localization masking processor, referred to in FIG. 1 for short as a processor, is connected with its output to an input of a sound-projecting audio playback system having at least one real source (1) with high directivity. This at least one real source (1) is arranged in a room (6), not shown in FIG. 1, which has sound-reflecting boundaries (11) like walls.

(9) After a characterization or calibration of the playback situation in a specific area, such as a room 6, in which the sound-projecting audio playback system is arranged, the parameters L(f); Δt; ϑ; φ were determined for each of the direct and projected transmission channels. Here, a direct transmission channel refers to a path 8 of a direct sound from the real source S.sub.1 1 and a projected transmission channel refers to a path 9 of an indirect sound from the virtual source S.sub.0 10. Here, L(f) indicates the complex frequency response, Δt the delay time, ϑ and φ the elevation and azimuth angles in the spherical coordinate system, which is used to describe a transmission direction of the respective sound bundle of the real source into the room.

(10) Subsequently, the localization-determining influence of direct sound is determined in a processor, such as a localization masking processor, for each playback signal x(t) having the desired localization direction ϑ.sub.Lok; φ.sub.Lok, and based thereon the number and properties of the sound bundles or beams with corresponding additionally generated sound instances 13, 13a, 13b, . . . , 13n required for playback with localization masking. Thereafter, the required control signal y(t) and the required radiation direction ϑ.sub.Beam; φ.sub.Beam are calculated for each sound bundle and forwarded to the sound projecting audio playback system for playback.

(11) Such a localization masking processor refers to an arrangement suitable for data processing, which can be controlled with the present method for influencing an auditory direction perception of a listener. Such control is advantageously performed with a program that implements the method for influencing an auditory direction perception of a listener.

(12) It is envisioned that the localization masking processor has an input for parameters L(f), Δt, ϑ, φ for each direct and each projected transmission channel. In addition, the localization masking processor has a second input for a playback signal x(t) with a desired localization direction ϑ.sub.Lok; φ.sub.Lok.

(13) The localization masking processor also has an output for outputting control signals y(t) and their radiation direction ϑ.sub.Beam; φ.sub.Beam for each sound bundle. This output is connected to the real source (1) of the sound-projecting audio playback system for controlling this real source (1), such as an array of loudspeakers.

(14) FIG. 2 shows a diagram of a schematic approach for generating a virtual source according to the prior art.

(15) FIG. 2 shows a real source S.sub.1 1 of a sound-projecting audio playback system, which in the example consists of eight loudspeakers 2, which, as illustrated, can be arranged in a single row or a single column or an array with several rows and columns. The sound generated by this real source S.sub.1 1 propagates into the room 6, for example, with the depicted radiation pattern 3. The radiation pattern 3, which is also referred to as a directional diagram, has a main emission direction with a main lobe 4 and a plurality of side lobes 5.

(16) The real source S.sub.1 1 is arranged in a space 6 shown by a dash-dash line. A receiver 7 is arranged in this room, for example at the indicated position.

(17) According to this schematic approach, a virtual source S.sub.0 10 is generated with the aid of reflections on the walls 11 of the room 6 and by a projection of the sound which is emitted by the real source S.sub.1 1 in the direction of the main lobe 4. In the illustrated example, this sound reaches the listener 7 after two reflections on the walls 11. The path of the reflected sound 9 causes a virtual source S.sub.0 10 to be generated, which the listener perceives in the example from the right rear.

(18) In the example, the direct sound from the real source S.sub.1 1 reaches the listener via path 8. This sound, which is emitted directly from the direction of the real source S.sub.1 1 originates from an area with focus-related amplitude attenuation in the area of the side lobes 5. Since this sound has at most the intensity of a side lobe 5 of the radiation pattern 3 and is thus perceived by the listener 7 weaker than the sound via the path 9, a resulting hearing event direction 12 is produced for the listener 7 in the direction of the virtual source S.sub.0 10.

(19) The illustrated exemplary radiation pattern 3 of the real source S.sub.1 1 is valid for a medium frequency range. As stated above, the resulting hearing event direction 12 of the listener 7 shown in FIG. 2 in the lower and upper frequency range cannot be successfully achieved or no longer achieved.

(20) FIG. 3 shows on the left-hand side of the figure a schematic time-amplitude diagram of the sound arriving at the listening position of a listener 7 from the direction of the virtual source S.sub.0 10 and directly from the direction of the real source S.sub.1 1. On the right-hand side of FIG. 3, the resulting hearing event direction 12 is shown with an exemplary arranged real source S.sub.1 1 and a virtual source S.sub.0 10. The visualization of real source S.sub.1 1 and virtual source S.sub.0 10 with the aid of loudspeaker symbols serves to simplify the explanation and is not a limitation.

(21) As can be seen, the sound from the real source S.sub.1 1 arrives at the listener 7 via the path 8 of direct sound, not shown in FIG. 3, as a direct sound component 15, for example at time t.sub.1 and an exemplary level L.sub.1 or amplitude. The illustrated level L.sub.1 or amplitude could be, for example, a sound pressure level in dB [SPL] (SPL: Sound Pressure Level) or a sound pressure measured in Pa.

(22) The sound of the virtual source S.sub.0 10, which arrives at the listener 7 via the path 9 of the reflected sound, which is not shown in FIG. 3, arrives at the listener for example at time t.sub.0. This time t.sub.0 is delayed with respect to the arrival of the direct sound from the real source S.sub.1 1 by a time difference Δt. The reason for this time delay Δt lies in the longer path 9 of the reflected sound compared to path 8 of the direct sound, as shown in FIG. 2.

(23) The sound of the virtual source S.sub.0 10 has a level L.sub.0 or an amplitude which is greater by the difference ΔL. The reason for this greater level L.sub.0 or amplitude is the directivity or radiation pattern 3, with which the sound of the virtual source S.sub.0 10 propagating via the path 9 to the listener 7 is radiated in the area of the main lobe 5 of the real source S.sub.1 1.

(24) In this example, a resulting hearing event direction 12 in the direction of the real source S.sub.1 1 arises, as shown on the right-hand side of FIG. 3. The reason for such a perception by the listener 7 is that according to the precedence effect, the sound arriving first at the listener 7 dominates the auditory direction perception.

(25) FIG. 4 shows a time-amplitude diagram with an additionally generated sound instance 13 according to the invention in an idealized diagram. The left-hand side of FIG. 4 shows again a schematic time-amplitude diagram of the reflected sound component 16 arriving from the direction of the virtual source S.sub.0 10 and of the direct sound component 15 arriving from the direction of the real source S.sub.1 1 directly at the listening position of a listener 7. The right-hand side of FIG. 4 shows the resulting hearing event direction 12 with an exemplary arranged real source S.sub.1 1 and a virtual source S.sub.0 10.

(26) As can be seen, the additionally generated sound instance 13 is provided in such a way that it arrives at the listener 7 earlier than the direct sound component 15 of the real source S.sub.1 1 by a time difference of Δt.sub.M1.

(27) In a particular embodiment, the additionally generated sound instance 13 can be provided in such a way that it arrives at the listener 7 at the same time as the direct sound component 15 of the real source S.sub.1 1. In this case, too, localization masking is possible by designing the additionally generated sound instance 13 so that signal features of the direct sound component 15 are augmented so as to make localization in its direction more difficult or prevent it altogether. This can for example prevent transients by way of additional signal components, or can ambiguate localization by phase smearing.

(28) In a further particular embodiment, the additionally generated sound instance 13 may be provided in such a way that it arrives at the listener 7 with a time delay, i.e. later than the direct sound component 15 of the real source S.sub.1 1.

(29) The localization masking level L.sub.M1 or the amplitude of the additionally generated sound instance 13 can, as shown in FIG. 4, be smaller than the level or the amplitude of the virtual source S.sub.0 10. The localization masking level L.sub.M1 or the amplitude of the additionally generated sound instance 13 can be smaller than, equal to or greater than the level L.sub.1 of the real source S.sub.1 1.

(30) Localization masking of the direct sound component 15 of the real source S.sub.1 1 is achieved by ideally adding an additionally generated sound instance 13. This generates a resulting hearing event direction 12 in the direction of the virtual source S.sub.0 10, as shown on the right-hand side of FIG. 4.

(31) FIG. 5 shows a time-amplitude diagram with an additionally generated sound instance 13 according to the invention in a non-idealized representation. The left-hand side of FIG. 5 shows the components of the reflected sound component 16 of the virtual source S.sub.0 10 arriving at the listener 7, as already known from FIG. 4, and the direct sound component 15 of the real source S.sub.1 1 as well as the additionally generated sound instance 13 in an idealized representation.

(32) Due to the imperfect focusing power of the real sources S.sub.1 1, caused by the non-ideal radiation pattern 3, an additional direct sound component 14 arises in the region of the side lobes 5, which reaches the listener 7 from the direction of the real source S.sub.1 1. This undesired additional direct sound component 14 transmitted directly to the listener 7 via the path 8 is shown in the left-hand side of FIG. 5. This additional direct sound component 14 arrives at the listener 7, for example, with a lower level or a smaller amplitude that is smaller by ΔL compared to the additionally generated sound instance 13. This additional direct sound component 14 arrives, for example, earlier than the additionally generated sound instance 13 with a time difference of Δt.

(33) The resulting hearing event direction 12 can be sufficiently influenced in this way for certain applications. There is an undesirable influence on the resulting hearing event direction 12 if the level or the amplitude of the undesired additional direct sound component 14 reaches or exceeds a localization-determining auditory perceptibility threshold for the listener 7. As shown in the right-hand side of FIG. 5, the resulting hearing event direction 12 can be influenced by two components. The first desired component influences the perception of the listener 7 in the direction of the virtual source S.sub.0 10, while the second undesired component influences the perception of the listener 7 in the direction of the real source S.sub.1 1.

(34) This drawback of the undesired additional direct sound component 14, which undesirably influences the perception of the listener 7 in the direction of the real source S.sub.1 1, is eliminated by a further measure according to the invention.

(35) For this purpose, the additional direct sound component 14 is localization-masked by newly providing a corresponding further additionally generated sound instance 13a, which impinges on the listener 7 from the direction of the virtual source S.sub.0 10. This provision of a further additionally generated sound instance 13a is shown in FIG. 6.

(36) The further additionally generated sound instance 13a is provided such that it arrives with a time difference Δt.sub.Mn before the additional direct sound component 14 in order to localization-mask the additional direct sound component 14. In the example in FIG. 6, the additionally generated sound instance 13a has a level or the amplitude L.sub.Mn, which may be greater than the level or the amplitude of the additional direct sound component 14.

(37) If the further additional direct sound component 14a generated by the further additional sound instance 13a, which reaches the listener 7 from the direction of the real source S.sub.1 1, still determines the auditory direction perception of the listener 7, the process can be further continued in the same way. Additionally generated, temporally preceding sound instances 13, 13a, 13b, . . . , 13n are cascaded until the listener 7 experiences a resultant hearing event 12 from the direction of the virtual source S.sub.0 10. This situation created by the method is shown in the right-hand side of FIG. 6.

(38) This situation is achieved when, after cascading n localization masking levels (with L.sub.Mn and Δt.sub.Mn), the additional direct sound component 14n arriving first at the listener 7 does no longer exceed the auditory perceptibility threshold of the listener 7 that determines the localization, thereby eliminating localization in the direction the real source S.sub.1 1. The example of FIG. 6 shows this cascading of n localization masking stages wherein all additionally generated sound instances 13, 13a, 13b, . . . , 13n temporally precede one another.

(39) Even if the signal of the additionally generated sound instance 13 shown in FIGS. 3 to 6 is separated in time from the direct sound component 15 of the real source S.sub.1 1, the signals of the additionally generated sound instance 13 and the direct sound component 15 or the additionally generated sound instance 13 and the reflected sound component 16 may at least partially overlap in time. Localization masking can be achieved even with such an overlap. The temporal relationships mentioned in the present description apply in this situation, for example, between the respective starting times or times of maximum cross-correlation between the additionally generated sound instance 13 and the direct sound component 15.