Reduced feedback in valve-ric assembly

Abstract

A personal hearing device with a first dome, a receiver, a speaker channel extending from the receiver through the dome to a speaker channel output, an acoustic vent channel extending from outside of the receiver and through the dome, where an acoustic separation is provided between the speaker channel output and the vent opening to reduce the amount of sound output by the receiver entering the vent channel.

Claims

1. A personal hearing device for positioning at or in an ear canal, the device comprising an outer housing, a first dome and a speaker provided in the housing, where: a speaker channel is provided extending from the speaker to a speaker channel output, the speaker channel output being provided in or at one side of the first dome, an acoustic vent channel is provided from a vent channel opening in or at the one side of the first dome to outside of the housing, where the speaker channel output and the vent channel opening are positioned with a shortest distance between them, and outside of the hearing device, of 1-5 mm.

2. A personal hearing device according to claim 1, where the vent channel has a length of 1-24 mm, an average cross section of 0.28-19.6 mm2 and forming a low pass filter with a roll of frequency of at least 500 Hz.

3. A personal hearing device according to claim 1 wherein the speaker channel output is provided within at least one first angle interval around a central axis of the first dome, and the vent channel opening is provided within at least one second angle interval around the central axis, the first and second angle intervals do not overlap.

4. A personal hearing device according to claim 3, wherein the first and second angle interval are provided with at least 90 degrees between them.

5. A personal hearing device according to claim 1, wherein the speaker channel output defines a first output direction and wherein the vent channel opening defines a second direction, and wherein an angle of at least 5 degrees exist between the first and second directions.

6. A personal hearing device according to claim 1, wherein a shortest path, outside of the device and from the speaker channel output to the vent channel opening, has one or more bends, where a total sum of angles of the bend(s) is at least 180 degrees.

7. A personal hearing device according to claim 1, further comprising a separation member positioned at the one side of the first dome, the speaker channel output and the vent channel opening output being provided in the first dome or between the first dome and the separation member, the separation member covering the speaker channel output and the vent channel opening when projected on to a plane perpendicular to a central axis of the dome.

8. A personal hearing device according to claim 1, wherein: a separation member is provided on the one side of the first dome, the speaker channel extending through the separation member, the vent channel opening is provided in the first dome or between the first dome and the separation member, and the separation member covers the vent channel opening when the separation member and the speaker channel opening are projected on to a plane perpendicular to a central axis of the first dome.

9. A personal hearing device according to claim 8, wherein the speaker channel extends along the central axis.

10. A personal hearing device according to claim 8, wherein the speaker channel extends through a stem of the separation member.

11. A personal hearing device according claim 8, further comprising a protection member, the speaker channel opening being provided in the separation member or between the separation member and the protection member, the protection member covering the speaker channel opening when the protection member and the speaker channel opening are projected on to the plane.

12. A personal hearing device according to claim 8, wherein the separation member is circular symmetric around the central axis.

13. A personal hearing device according to claim 1, further comprising a valve assembly with an electromechanical actuator configured to open and close the acoustic vent channel.

14. A personal hearing device for positioning at or in an ear canal, the device comprising an outer housing, a first dome and a speaker provided in the housing, where: a speaker channel is provided extending from the speaker to a speaker channel output, the speaker channel output being provided in or at one side of the first dome, an acoustic vent channel is provided from a vent channel opening in or at the one side of the first dome to outside of the housing, where the speaker channel output and the vent channel opening are separated through an acoustical separation arrangement to reduce the acoustical feedback, and wherein the venting channel has a second side opening under a flap of the dome for venting the sound to outside the hearing device.

15. A personal hearing device according to claim 14, further comprising an acoustically transparent foam in or at the speaker channel and/or the acoustical venting channel.

16. A personal hearing device according to claim 1, further comprising an acoustically transparent foam in or at the speaker channel and/or the acoustical venting channel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, preferred embodiments are described with reference to the drawings, wherein:

(2) FIG. 1 illustrates a first embodiment of a personal hearing device with a central sound channel and a acoustic vent channel covered by a separation member,

(3) FIG. 2 illustrates the sound paths in the first embodiment,

(4) FIG. 3 illustrates an embodiment with a protection member for wax protection,

(5) FIG. 4 illustrates a dome with a speaker channel and a vent channel,

(6) FIG. 5 illustrates the distance between the speaker channel output and the vent channel opening of the embodiment of FIG. 4,

(7) FIG. 6 illustrates yet an embodiment with the speaker channel output and the vent channel opening are directed in different directions but below a separation member,

(8) FIG. 7 illustrates the distance between the speaker channel output and the vent channel opening in the embodiment of FIG. 6,

(9) FIG. 8 illustrates surfaces of equal dip frequency at corresponding observation points inside a volume,

(10) FIG. 9 illustrates effect of different spacing of speaker and vent channels on feedback reduction,

(11) FIG. 10 illustrates an embodiment of a personal hearing device fully positioned in an earcanal,

(12) FIG. 11 illustrates an embodiment of a personal hearing device positioned at an earcanal,

(13) FIG. 12 illustrates a section of a sound generator channel known from the prior art,

(14) FIG. 13 illustrates an embodiment of a portion of the speaker channel and acoustic vent channel,

(15) FIG. 14 illustrates a personal hearing device with a dome with an acoustic vent channel opening under a flap of the dome.

DETAILED DESCRIPTION OF THE INVENTION

(16) In FIG. 1, a personal hearing device 10 is seen having a first dome 16, a receiver 14 provided in a housing 12 attached to the dome. The first dome is usually provided for attaching or fixing the device 10 inside an ear canal of a person. The first dome may be substantially sealing in the manner that sound and gas transport across the dome is impossible or at least impeded. Situations may exist where the first dome has a special channel, for example a small hole of any diameter in the range of 0.5-1 mm, therein (in a thin sealing wall of the dome, for example, a flexible flap of the dome) for allowing sound with a small intensity of air to travel from one side to the other side of the dome.

(17) The upper side in the dome is to be directed toward the ear drum of the person. The speaker channel output 20 is provided in the upper portion and a speaker channel 18 exists between the receiver 14 (output) and the speaker channel output 20.

(18) An acoustic vent channel 22 is provided having a vent channel opening 24. The acoustic vent channel 22 may extend to an opening 22′ outside of the housing 14 on the lower side of the first dome. A vent of this type may have a valve configured to open and close the vent. This vent may be used for e.g. preventing the so-called occlusion effect.

(19) A separation member 26 is provided. The sound channel 18 extends through the stem of the separation member to the speaker channel output which is provided on the upper side of the separation member.

(20) The vent channel opening on the other hand is provided in the first dome or between the first dome and the separation member. It is seen that the separation member covers the vent channel opening when projected on to a plane perpendicular to the central axis A of the first dome. Often, the first dome, or at least an upper or outer surface thereof, will be symmetric, so that the central axis is a symmetry axis.

(21) The function of the separation member thus is to reduce transfer of sound output by the speaker channel output 20 to the vent channel opening 24.

(22) A purpose of the present device is to on the one side provide the vent 22 to allow low frequency sound to exit the space between the dome 16 in the ear canal (for venting air between the dome and eardrum to outside of earcanal, in order to reduce the occlusion) while, on the other side, to not have too much of the sound output by the speaker channel output escape the space between the speaker channel output and the ear drum through the vent 22 (to reduce the acoustical feedback). This is ensured, in this embodiment, by the separation member 26 increasing the distance, which sound must take between the speaker channel output and the vent channel opening, compared to the same set-up where the separation member is omitted. Preferably, the sound from the speaker channel output has to travel at least 1 mm in order to reach the vent channel opening.

(23) In FIG. 1, the separation member 26 is dome-shaped. However, a number of other shapes may be used. The overall purpose of the separation member is to increase the distance which sound must take from the speaker channel output to the vent channel opening.

(24) Clearly, the shortest path will extend over an along convexities but simply across concavities of the structure.

(25) Another parameter which is operable to reduce the intensity of sound from the speaker channel output reaching the vent channel input is the angle which the sound must negotiate through this path, which influences the travelling distance of the sound, so that the distance may be increased by adjusting the angle.

(26) FIG. 8 is a figure from [M. D. Burkhard and R. M. Sachs, Sound Pressure in Insert Earphone Couplers and Real Ears, Journal of Speech and Hearing Research, vol. 20, pp 799-807 (1977)]: Surfaces of equal dip (antiresonance) frequency at corresponding observation points inside the volume of the 2CC simulator.

(27) It is seen that sound emitted at 90 degrees to the sound output is attenuated within a much lower distance than sound output directly from the opening. Thus, the larger the angle which the sound must negotiate, the lower will the intensity be of the sound reaching the opening.

(28) In the embodiment of FIG. 2, it is seen that in addition to the actual distance to be covered by the sound, the sound has to firstly travel perpendicularly to the speaker channel opening and then turn 180 degrees, before it again turns 90 degrees to enter the vent channel opening. A total of 360 degrees thus is required for the sound to travel into the vent channel opening.

(29) In this respect, the sound output of the opening is dependent on the angle of the sound relative to the opening—but not to the same degree to the direction of the sound passage leading to the opening.

(30) In FIG. 1, the speaker channel output has an opening which is, in the drawing, horizontal. The main direction of sound output by an opening is a direction perpendicular to a plane defined by the opening, such as the outer edge(s) thereof, if such a plane exists.

(31) Naturally, the sound entering the vent channel opening will see the same effect. The larger the angle from the opening angle, the less sound will actually enter the channel.

(32) The complete angle which sound must negotiate between the speaker channel output and the vent channel opening thus is derived from that output direction and summed until the angle of the sound is along the direction of the vent channel opening.

(33) In FIG. 1, a slidable element 19 is illustrated which may open and close the opening 22′. This slidable element 19 may then form a component of a valve assembly for opening and closing the acoustic vent channel, for example using an electromechanical actuator.

(34) The speaker channel 18 may be partly formed by a relatively thin walled tube, such as a metal tube 1301 illustrated in FIG. 13 with a wall thickness of 10-60 μm, such as 25-35 μm, which still provides sufficient stiffness. The inner radius of this tube may be 1-3 mm, such as 1.5-2.4 mm.

(35) The acoustic vent channel 22 may have a diameter of 2-4 mm, as it still should fit inside an ear canal. This channel 22 may also be formed by a tube e.g. 1302 in FIG. 13, which may be metal or a polymer having a wall thickness of 0.05-0.3 mm, such as around 0.1 mm. The inner radius 1303 of this tube may be 3.3 mm, or another value in the range 2.2-4 mm. The external radius 1304 of this tube may be 3.5 mm, or another value in the range 2.4-4.2 mm. A side venting opening 1305 may be provided, as described in EP 3471432.

(36) In FIG. 12, a speaker channel known from the prior art is illustrated. The tube 1202 forms a speaker channel with an inner radius 1202 of 1.4 mm, and external radius 1203 of 2.5 mm. The tube has plastic walls of 0.3 mm thickness.

(37) FIG. 2 illustrates a device as that in FIG. 1 but where the first dome 16 and the receiver have been removed for clarity. The straight upward arrow illustrates the sound path of sound from the receiver 14 and the left, curved, downwardly directed arrow illustrates the sound path of the vent 22. The line above the dome 26 illustrates the path which sound from the sound outlet 20 must take to reach the vent channel opening 24.

(38) FIG. 3 illustrates an embodiment similar to that of FIG. 1. The same elements have the same reference numerals, and the difference is the presence of a preventing member, 36, which may also be dome shaped, which is provided above or over the speaker channel 18 to provide a wax protection. Then, the speaker channel outlet is now provided between the separation member 26 and the preventing member 36. The preventing member then may prevent ear wax from being forced into the speaker channel output when the device 10 is transported into the ear canal.

(39) FIG. 4 illustrates an alternative embodiment with a first dome 261 having a speaker channel 181 with a speaker channel outlet 201 and a vent channel 221 with a vent channel opening 241. The receiver etc. is not illustrated.

(40) Foam may be provided inside any of the speaker channel 18, acoustic vent channel 22, and/or the vent channel 221. The foam may include reticulated polyester or polyether polyurethane material. The foam material may have the porosity in the range 70-100 ppi (pores per inch), for example, 70, 75, 80, 85, 90 or 95 ppi. The foam may have a shape of a sleeve or tube or ring for positioning on a side of the tube 1302 in FIG. 13.

(41) Even though both channels extend through the stem of the dome, they flare out at the upper end to allow the output and the outlet to have a minimum distance, 261, illustrated in FIG. 5, between them. In addition, it is seen that the directions of the openings also are directed away from each other so that the angle which must be negotiated by the sound is more than a certain threshold value, such as 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, or 180 degrees.

(42) In the present embodiment, the opening and output are provided symmetrically around the central axis A. This is not a requirement.

(43) In FIG. 6, yet another embodiment is illustrated where the features in common with FIG. 1 have the same numerals.

(44) In the embodiment of FIG. 6, the sound channel 18 extends into a portion of the dome 16 via an opening 182 in the central sound channel. The speaker channel output 202 is provided below the separation member 26 which, in this situation, does not have a central speaker channel output.

(45) In the same manner, the vent channel extends from an opening 22′ below the dome 16 to the vent channel opening 242. The vent channel is not illustrated in the present cross section but exists in other cross sections.

(46) The speaker channel output path and the vent path are seen in FIG. 7 as well as the shortest path which the sound must take from the speaker channel output to the vent channel opening.

(47) In FIG. 9, it is illustrated that a medium spacing with a shortest distance between a speaker channel output and the acoustic vent channel opening provides a certain feedback reduction. The large spacing provides another feedback reduction. In an exemplary test measurement, a microphone signal is measured outside the earcanal, for example as by a typical BTE microphone. Another acoustic signal is measured by a second microphone near the eardrum. In a first test, a closed dome is provided with a very small distance between the speaker channel output and the vent channel opening. At a certain frequency, e.g. 3 kHz, the difference between signals of both microphones approaches 50 dB difference. The possible gain margin of the hearing aid will be reduced and will not function properly. With the medium and large distances between the speaker channel output and the vent channel opening, the BTE microphone can still measure external audio signals and the hearing device functions properly.

(48) FIG. 10 illustrates an embodiment of a personal hearing device fully positioned in an earcanal. A volume can be seen between the dome 16 and the eardrum. The speaker provides the sound to this volume. The vent releases the air from this volume to reduce the occlusion, while the vent channel opening and the speaker channel output are separated and interface this volume. In FIG. 11, a personal hearing device is positioned at an earcanal. A similar volume can be seen as with reference to FIG. 10.

(49) According, to the invention a personal hearing device is provided for positioning at or in an ear canal, the device comprising an outer housing, a first dome and a speaker provided in the housing, where: a speaker channel is provided extending from the speaker to a speaker channel output, the speaker channel output being provided in or at one side of the first dome, an acoustic vent channel is provided from a vent channel opening in or at the one side of the first dome to outside of the housing, where the speaker channel output and the vent channel opening are separated through an acoustical separation arrangement to reduce the acoustical feedback.

(50) FIG. 14 illustrates a personal hearing device with a dome with an acoustic vent channel opening under a flap of the dome. The speaker outputs the sound through the speaker channel 1405, with the speaker channel output 1402. The dome has a flexible member 1401 for comfortably positioning a hearing device inside or at the earcanal. The acoustical venting channel 1404 is provided, with the opening 1408 just outside the dome and toward the earcanal, and with another opening 1403 under the dome flap 1401. The channels 1404 and 1405 are acoustically isolated from each other. The separation 1409 between the speaker channel output 1402 and the venting channel opening 1408 should be observed according to the present invention in order to reduce the feedback. The separation 1409 can be provided through the distance, angle or other solutions according to above embodiments.

(51) The speaker channel and the venting channels may be also oriented sidewise as FIGS. 6 and 7.

(52) Advantageously, a path length of the venting channel 1404 should be as short as possible, in order to improve the acoustical venting performance, for example, the shorter and wider the venting channel provides a better acoustic bandwidth, as described in European patent application number EP 17196716.9 and European patent application published as EP3471432. In order to provide a dome with such venting solution, the vent opening 1403 is provided as close to the dome flap 1401 as possible.

(53) The dome may be mounted through a sleeve, plastic tube or in another way in a position 1407 between the venting opening 1403 and the rest of the hearing device, e.g. between the

(54) opening 1403 and the speaker housing 1410. In FIG. 14, it is illustrated that the dome is retained through a locking mechanism between the dome tube and the venting tube, for example, through a snap lock 1406.

(55) The locking mechanism may require a hard material, while the dome flap 1401 may be made from a softer material as a softer “umbrella” for a user comfort. Such dome may be made using a 2 k molding. Such dome may be comfortable to a wearer, while also having a good retention on the hearing device. This also allows to position retention ribs 1406 further away from the flap 1401, while the venting opening 1403 is positioned closer the dome flap 1401.

(56) The venting opening 1403 may be made by circular venting openings, e.g. as elements 22-1 in FIG. 17 of European patent application published as EP3471432.

(57) Different structural elements of the receiver channel and venting channel may be combined and molded from the same material as the dome tube and stem.