JP2013530654A - Hearing aid suitable for wind noise suppression - Google Patents

Abstract

The hearing aid (100) includes a microphone, a signal processing unit, an electro-acoustic output transducer, a housing (101), and a windshield cover (102). The housing has a surface having a microphone port (112, 113). It is attached to the housing, covers the microphone port, and is configured such that sound is guided in the gap between the windshield cover and the housing, thereby transmitting sound from the surroundings to the microphone port. The first dimension of the cross-section of the gap provided is in the range of 0.15 mm to 0.5 mm, and the shortest distance along the gap from the microphone mouth to the opening of the gap facing the periphery is at least 1 mm.

Description

  The present invention relates to a hearing aid. More specifically, the present invention relates to a hearing aid that suppresses wind noise.

  In the present disclosure, a hearing aid system is understood as a system that mitigates hearing loss for users with hearing impairments. The hearing aid system may be mono (one ear type) having only one hearing aid, or may be binaural (both ear type) having two hearing aids.

  In this disclosure, a hearing aid is understood as a small, small electronic device designed to be worn behind or in the ear of a person with hearing impairment. The hearing aid includes one or more microphones, a small electronic circuit with a signal processing device, and an acoustic output transducer. The signal processing device is preferably a digital signal processing device. The hearing aid is housed in a casing suitable to fit behind or in a person's ear.

  There are various types of hearing aids. One example is a Behind-The-Ear (BTE) hearing aid. BTE hearing aids are worn behind the ears. More precisely, a housing containing major electronics parts is mounted behind the ear. An earplug or an earpiece that emits sound to the user of the hearing aid is mounted in the ear, for example, in the ear canal (in the ear canal). In conventional BTE hearing aids, a sound tube is used because an output transducer, usually called a receiver in terminology of hearing aids, is disposed within the housing of the electronic circuit unit. In some recent types of hearing aids, the receiver is placed in the earplug in the ear, and for this purpose conductive members comprising electrical conductors are used.

  In this application, wind noise is defined as the result of pressure fluctuations at the microphone position of the hearing aid due to turbulence. On the other hand, the acoustic sound produced by the wind is not regarded as wind noise here because the sound is part of the natural environment.

  Wind noise is a serious problem in hearing aids. Wind noise can reach 100 dB Sound Pressure Level (SPL) or higher. The acoustic perception with a hearing aid in a strong wind environment may be worse than without the hearing aid, so that the user of the hearing aid may switch off his or her instrument during strong winds.

  The magnitude and spectrum of wind noise varies significantly depending on wind speed, wind direction to the appliance, individual hair length, mechanical obstructions like hats and other factors. . There are the following documents regarding noise, effects and causes. H. Dillon et al., `` The sources of wind noise in hearing aids '', IHCON 2000, and I. Roe et al., `` Wind noise in hearing aids: Causes and effects '', submitted to the Journal of the Acoustical Society of America.

  It has been proposed to counteract wind noise by mechanical structural measures, but these are generally too large or too bulky for implementation in hearing aids.

  Furthermore, such an approach may lead to an increase in the sound attenuation of the desired sound.

  Accordingly, it is a feature of the present invention to provide a hearing aid that overcomes at least these problems and has improved wind noise suppression.

  In a first aspect, the present invention provides a hearing aid according to claim 1.

  There is provided a hearing aid including a windshield (wind shield) and a hearing aid housing that effectively suppress wind noise.

  In a second aspect, the present invention provides a hearing aid according to claim 14.

  A hearing aid is provided that is particularly suitable for suppressing wind noise and miniaturization.

  Further advantageous features are apparent from the dependent claims.

  Still other features of the present invention will become apparent to those skilled in the art from the following description describing the invention in detail.

FIG. 4 shows a perspective view of selected portions of a hearing aid according to an embodiment of the present invention. It is a 1st perspective view which shows the windshield cover by the Example of FIG. It is a 2nd perspective view which shows the windshield cover by the Example of FIG. FIG. 2 is a perspective view of a hearing aid housing according to the embodiment of FIG. 1. Typical measurements of power spectrum as a function of frequency for a front microphone of a conventional BTE hearing aid and a BTE hearing aid with a windshield cover according to an embodiment of the invention when exposed to wind at a speed of 4 m / s Indicates. Typical measurements of power spectrum as a function of frequency for a conventional BTE hearing aid and a BTE hearing aid rear microphone with a windshield cover according to an embodiment of the invention when exposed to wind at a speed of 4 m / s Indicates. 1 schematically shows a cross section of a hearing aid according to the embodiment of FIG. 1 schematically shows a cross section of a hearing aid according to another embodiment of the invention.

  By way of example, a preferred embodiment of the invention is shown and described. Of course, the invention is capable of other and different embodiments, and its several details are capable of modifications in all obvious respects, all without departing from the invention. Accordingly, the drawings and descriptions are to be regarded as illustrative in nature, and not as restrictive.

  For hearing aids according to various aspects of the present invention, it has been found that the suppression of wind noise can be significantly improved over a wide band of frequencies.

  The hearing aid is provided with a sound transmission channel for guiding sound from the surrounding (ambient environment) to the microphone inlet, and the flow of air in the sound passage channel. It was found that the ratio (ratio) of wind noise suppression with respect to acoustic attenuation can be improved by making the layered before reaching the microphone mouth.

  For hearing aids according to various aspects of the invention, it has further been found that the ratio of wind noise suppression to acoustic attenuation can be improved by appropriately selecting the length of the sound passage channel.

  It has been found that the cross-section design of the sound passage channel can further optimize the ratio of wind noise suppression to the sound attenuation.

  Consider a small diameter (small diameter) tube configured to transmit sound from the surroundings (ambient environment) to the microphone mouth. The tube develops into laminar flow after a distance shorter than the tube length, under normal conditions (ie wind speed), the turbulence starting at the tube opening is not maintained in the tube. Designed to be able to. Such a tube is obviously beneficial because it prevents the generation of turbulence around the microphone mouth, but the turbulence still induces pressure fluctuations around the opening of the tube, which effectively causes the microphone mouth to The wind noise is picked up by this.

  Consider a tube with a fairly large diameter (large diameter). The flow in the tube is usually turbulent with respect to the generation conditions. Such a tube is obviously not beneficial because it cannot prevent the generation of turbulence around the microphone mouth, but the pressure fluctuations caused by the turbulence around the tube opening are not efficiently guided towards the microphone mouth. Instead it tends to dissipate.

  Therefore, the first small-diameter tube is very suitable for suppressing wind noise generated by turbulent air flowing directly into the tube, while the second large-diameter tube is wind-induced by turbulence at the opening of the tube. Very suitable to avoid the sound being picked up.

  Here, the setting using two parallel plates, that is, the two parallel plates are separated so as to form a gap (gap) suitable for carrying sound from the surroundings toward the microphone mouth, Consider a setting in which the microphone mouth is located in the gap between and the center of one of the plates. Such a setting is clearly very suitable for suppressing wind noise generated by the wind flowing perpendicular to the plate surface. By carefully selecting the dimensions of the plate (s), as will be described later, the plate is very suitable for suppressing wind noise generated by the wind flowing along the plate surface.

  If the in-plane wind flow is perpendicular to the edges of the plates, the first is that the turbulence (for the most commonly generated wind speed) is the gap between the plates. In order not to be retained, it is necessary that the spacing between the plates is sufficiently small, and secondly, turbulence at the edge of the plate is converted into laminar flow at the microphone mouth position. In order to do so, the lateral extent (propagation distance) of the plate (s) needs to be sufficiently large.

  The propagation of the turbulence induced pressure fluctuations is preferably modeled by a near-field model, while the propagation of the main part of the desired sound from the surroundings is a far-field model ( Since the attenuation of turbulence-induced pressure fluctuations strongly depends on the propagation distance, the surface spread can be increased by increasing the lateral spread (propagation distance) of the plates. It has been found that the ratio of wind noise suppression to acoustic attenuation for wind flow flowing in and parallel to the edges of the plates can be improved.

  The acoustic attenuation of sound propagating under the windshield or roughly propagating in the sound passage channel according to various embodiments of the present invention is greatly increased when the plate spacing is narrower than 0.15 mm. I found out to start. On the other hand, it is known that the propagation distance required for the transition of turbulence to laminar flow depends on the value of the plate spacing squared. Therefore, the preferred value of the plate spacing is selected from the range where the acoustic attenuation is limited (limited) and the flow for the most commonly occurring wind speed is quickly converted to laminar flow.

  For the flow between two parallel plates, the distance L required to convert turbulence into laminar flow is given by:

L = h ² v / (8ν)

  Here, h is an interval between two parallel plates, v is a flow velocity (that is, wind speed here), and ν is a viscosity coefficient (kinematic viscosity) of air.

  In various embodiments of the present invention, it has been found that the acoustic attenuation of sound propagating in the gap remains small if the propagation distance is at least about 10 mm. A particular advantage of the hearing aid according to the invention is therefore that wind noise suppression can be increased without reducing the sensitivity of the hearing aid.

  Reference is first made to FIG. 1, which shows selected portions of a hearing aid 100 according to a first embodiment of the present invention. The hearing aid 100 includes a housing part 101, a windshield cover 102, a connector part 103, and an earpiece (not shown). The housing part 101 includes two microphones, a small electronic circuit including a signal processing device, an acoustic output transducer, a toggle switch 104 and a push button 105. The connector portion 103 is designed to transmit an acoustic signal from the output transducer to the earpiece and further toward the eardrum of the user wearing the hearing aid. The windshield cover is configured to protect the microphone opening from dust and moisture and suppress wind noise. The hearing aid housing 101 and the windshield cover 102 are formed on the side openings 108a and 118b (the same gap is also formed on the opposite side of the hearing aid housing when the windshield cover is attached to the hearing aid housing). Are configured to form). The gaps are configured to transmit sound into the gap between the hearing aid housing and the windshield cover. A front indent 119 is configured to allow the windshield cover to be removed from the hearing aid housing using a simple tool.

  Referring now to FIG. 2, FIG. 2 shows the windshield cover 102 according to the first embodiment of the present invention from a first perspective. The windshield cover allows the user to access a convex side 106 that is designed to face away from the hearing aid housing (not shown) and the toggle switch 104 of the hearing aid housing. And a configured hole 107.

  Referring to FIG. 3 below, FIG. 3 shows the windshield cover 102 according to the first embodiment of the present invention from a second perspective. The windshield cover has a concave side 108 designed to face the hearing aid housing (not shown). The concave side 108 has protrusions 109a, 109b, 110a and 110b configured to snap lock the windshield cover onto the hearing aid housing (snap locking). The concave side further comprises column like structures 111a and 111b and protrusions 112, which assist in guiding the windshield in the correct position when the windshield cover is mounted on the hearing aid housing. It is configured.

  Reference is now made to FIG. 4, which schematically illustrates the hearing aid housing 101 according to a first embodiment of the present invention. The housing 101 has four recesses 109c, 109d, 110d (not visible) configured to snap-fit into two microphone openings 112 and 113 and corresponding projections 109a, 109b, 110a and 110b of the windshield. have. The hearing aid housing has holes 111d (not visible) 111 configured to receive the columnar structures 111a and 111b of the windshield cover, and a rectangular indent 120 that receives the projection 122 of the windshield cover. doing. A band-like projection 114 and another projecting structure 115 located between the microphone mouths are combined to form the concave side 108 of the windshield and the surface regions 116a and 116b of the hearing aid housing 101. It works to ensure a uniform and well defined gap distance between them. The protruding structure 115 surrounds the toggle switch 104 and incorporates the indentation (s) 110d (not visible) and the hole (s) 111d (not visible). The surface regions 116a and 116b define a surface along the sound propagating from the surrounding environment toward the microphone ports 112 and 113. The surface regions 116a and 116b and the protruding structures 114 and 115 are surrounded by a rim 117. The rim is configured to form openings 118a and 118b when the windshield cover is snap fitted onto the hearing aid housing. The indentation 120 ensures that the windshield cover can be easily removed from the hearing aid housing using a tool.

  The gap distance between the windshield cover 102 and the surface regions 116a and 116b of the hearing aid housing is 0.3 mm.

  In a variation of the first embodiment of the invention, the gap distance between the windshield cover 102 and the surface regions 116a and 116b of the hearing aid housing is in the range of 0.15 mm to 0.5 mm, preferably from 0.20 mm. It is between 0.35mm. Such a gap distance necessarily entails that the air flowing under the windshield cover is substantially layered after a short propagation distance for most normally occurring wind speeds and propagates under the windshield cover. As a result, the acoustic attenuation of the sound is necessarily small.

  According to the first embodiment of the present invention, the shortest (minimum) distance along each gap from the gaps 118a and 118b to the corresponding microphone ports 112 and 113 (ie, between the windshield cover 102 and the hearing aid housing 101). The running in the gap is 2 mm. In this application, the term “shortest distance along the gap” refers to the shortest distance between the edge of the microphone mouth and the corresponding gap facing the periphery defined by the edge of the windshield cover and the hearing aid housing. between an edge of a microphone inlet and a corresponding opening, towards the surroundings, defined by an edge of the wind shield cover and the hearing aid housing).

  In a variation of the first embodiment of the invention, the shortest distance along the gap is at least 1 mm, at least 2 mm, or in the range between 1 mm and 3 mm (ie, longer than 1 mm and shorter than 3 mm). Surprisingly, it has been found that even such a relatively limited gap distance provides a measureable and significant improvement in wind noise reduction.

  There are advantages to extending the shortest distance along the gap for several reasons. First, as already mentioned in the previous section, when a strong wind speed reaches the microphone port, the wind flow in the gap necessarily involves a layered structure. Secondly, the attenuation of turbulence induced pressure fluctuations formed along the edge of the windshield increases strongly with distance. Finally, pressure fluctuations induced by uncorrelated turbulent whirls formed along the edge of the windshield are at least partially canceled from each other at the microphone mouth and the shortest distance along the gap. The cancellation efficiency generally increases with this, because the cancellation of two uncorrelated turbulent vortices is optimized when the distance between the microphone mouth and each vortex is the same. It is. On the other hand, the minimum distances down to 1 mm example has been found to provide a good compromise between high wind noise suppression and a flat microphone response. In a particular variant of the first embodiment of the invention, the gap distance is 0.3 mm and the shortest distance along the gap is 1.5 mm.

  According to the first embodiment of the present invention, the widths of the gaps 118a and 118b are both 5 mm.

  In a modification of the first embodiment of the present invention, separate openings 118a and 118b are not provided. Instead, the full length of the windshield defines the width of both the openings.

  In a further variation of the first embodiment of the invention, the gaps 118a and 118b have a width of at least 2 mm, at least 3 mm, or at least 5 mm. In order to avoid the pressure fluctuations induced by the turbulence around the gap from being efficiently guided to the microphone mouth and to dissipate it instead, it is advantageous to have wide openings. . On the other hand, an embodiment having a gap with a width in the range of about 2 mm to 5 mm has been found to provide a good compromise between high wind noise suppression and a flat frequency microphone response.

  According to a further variation of the first embodiment of the present invention, the shortest distance along the gap between the gaps 118a and 118b and the edges of the corresponding microphone ports 112 and 113 is the variation of the width of the hearing aid housing. Because of fluctuating.

  In a variation of the first embodiment of the invention, the width of the gaps 118a and 118b is such that the ratio of the width of the gap to the length of the shortest distance is maintained substantially constant. Depends on fluctuations.

  Reference is now made to FIG. 5, which shows typical measurements of power spectrum as a function of frequency for a conventional BTE hearing aid and a BTE hearing aid having a windshield cover according to an embodiment of the present invention. The measurement was performed with the hearing aids (plural) exposed to a wind speed of 4 m / s. Both hearing aids are equipped with two microphones and the power spectrum was obtained using the front microphones in the two hearing aids. The above figures clearly show that a significant reduction in wind noise can be obtained by using a hearing aid with a windshield cover according to the present invention.

  Reference is now made to FIG. 6, which shows a typical measurement similar to that described with reference to FIG. 5, except that the rear microphones in the two hearing aids were used to obtain the power spectrum. Results are shown. The figure clearly shows that the amount of wind noise reduction that can be achieved depends on the position of the microphone. FIGS. 5 and 6 show that the typical power spectrum for a BTE hearing aid according to the invention is relatively insensitive to the microphone position, while this may not be the case with previous BTE hearing aids. Show.

  Reference is now made to FIG. 7, which shows a fairly schematic cross section of the hearing aid 100 according to the first embodiment of the invention. The cross section shows a plane perpendicular to the approximate longitudinal axis of the housing defined by the line connecting the first and second microphone ports and intersecting the first microphone port. The drawing shows a cross section of the hearing aid housing 101, the windshield cover 102, the first microphone port 112 and the first microphone 121.

  According to a first embodiment of the present invention, the hearing aid housing 101 has a circumferential cross-section in a plane perpendicular to the approximate longitudinal axis of the housing defined by a line connecting the first and second microphone ports ( a cross-section with a circumference in a plane), and when the windshield cover 102 is provided on the housing, the cross-sectional length is about 30% of the circumference of the housing in the plane. Hearing aids are designed to have a height.

  In a modification of the first embodiment of the present invention, the length of the cross section of the windshield cover is at least 30% of the housing circumferential length. This makes it possible to obtain a significant shortest distance along the gap even with a hearing aid housing having a relatively small housing periphery. In another modification of the first embodiment of the present invention, the length of the cross section of the windshield cover is less than 30% of the peripheral length of the housing. This type of windshield cover is advantageous when the shortest distance along the gap is required to be relatively short in order to obtain a specific microphone frequency response.

  According to a first embodiment of the invention, the hearing aid housing comprises an upper part and a lower part that fit together.

  According to another modification of the embodiment of the first invention, the windshield cover includes the hearing aid except for a gap opening (gap opening) formed between both ends of the windshield cover. Extends substantially all the way around the hearing aid housing. According to a further variant, the microphone mouths are located on the housing surface opposite to the gap opening, so that for a given hearing aid housing, The maximum achievable shortest distance between the microphone mouth edge (s) and the corresponding gap mouth (s) is achieved, and according to a particular variant, the gap mouth is connected to the upper surface of the hearing aid (in the surface opposite the surface of the hearing aid that is adapted to rest upon the ear, i.e., the surface opposite the surface of the hearing aid housing configured to rest on the intended hearing aid user's ear of the intended hearing aid user).

  Reference is now made to FIG. 8, which shows a fairly schematic cross section of a hearing aid 200 according to a second embodiment of the present invention. The figure shows the upper and lower hearing aid housing parts 201 and 202, the microphone mouth 212, the microphone 121 and the sound passage channel 205. The sound passage channel 205 is provided to guide sound from the surroundings to the microphone port 212. The sound passage channel provides sound propagation through the interior of the hearing aid housing, rather than propagation in the gap between the windshield cover and the outer surface of the hearing aid housing. This eliminates the need for the windshield cover, thereby minimizing the size of the hearing aid housing. Another advantageous aspect is that the sound passage channel can be freely shaped, thereby increasing the shortest achievable distance between the microphone mouth (s) and the sound passage channel opening. it can. The sound passage channel has a cross section with a length of 1.5 mm, a first dimension of 0.3 mm and a second dimension of 5 mm.

  According to a variant of the second embodiment of the invention, the sound passage channel has a length of at least 1 mm, or a length in the range of 1 mm to 3 mm, and the first dimension of the cross section is from 0.15 mm to 0.5 mm. In the range of mm, preferably between 0.20 mm and 0.35 mm, the second dimension of the cross section is at least 2 mm, at least 3 mm or at least 5 mm.

  According to a further variation of the second embodiment of the present invention, the hearing aid is configured to form the sound passage channel and to place and secure the electronic components within the hearing aid housing. An insert is provided.

  According to a further variation of the first embodiment of the present invention, the windshield includes small holes just above the microphone mouths. Surprisingly, this has been found to give the hearing aid microphone a low sensitivity to vibration and therefore feedback, while still providing good wind noise suppression. Holes with diameters ranging from 0.15mm to 0.30mm have been found to be appropriate.

  Other modifications and variations in structure and procedure will be apparent to those skilled in the art.

Claims (20)

With microphone, signal processing unit, electro-acoustic output transducer, housing and windshield cover,
The housing has a surface with a microphone port;
The windshield cover is attached to the housing and is configured to cover the microphone port and form a gap with the housing, thereby providing a passage for the passage of sound from the surroundings to the microphone port. The average distance between the housing and the windshield cover is in the range of 0.15 mm to 0.5 mm, and the shortest distance along the gap from the microphone port to the edge of the windshield cover is at least 1 mm;
hearing aid.   The hearing aid according to claim 1, wherein the shortest distance along the gap from the microphone port to the edge of the windshield cover is longer than 1 mm and shorter than 3 mm.   The windshield cover is configured so that sound is sent into the gap between the windshield cover and the housing through a gap formed by the edge of the windshield cover and the housing. The hearing aid described.   4. The housing according to claim 1 to 3, wherein the housing comprises distance holding means configured to provide support to the windshield cover, thereby ensuring a uniquely defined spacing between the windshield cover and the housing. Hearing aids.   The hearing aid according to any one of claims 1 to 4, wherein a shortest distance along the gap from the microphone mouth to an edge of the windshield cover is at least 2 mm.   The hearing aid according to any one of claims 1 to 5, wherein a shortest distance along the gap from the microphone mouth to the edge of the windshield cover is longer than 2 mm and shorter than 3 mm.   The hearing aid according to any one of claims 1 to 6, wherein a distance between the housing and the windshield cover is in a range of 0.20 mm to 0.35 mm.   Hearing aid according to any one of claims 1 to 7, wherein the width of the gap at the edge of the windshield cover is at least 2 mm.   Hearing aid according to any one of claims 1 to 8, wherein the width of the gap at the edge of the windshield cover is at least 3 mm.   Hearing aid according to any one of the preceding claims, wherein the width of the gap at the edge of the windshield cover is at least 5 mm. The housing has a circumferential cross section in a plane perpendicular to the longitudinal axis of the housing and intersecting the microphone port;
The windshield cover has a cross section having an overall length longer than 30% of the first circumferential length in the plane when attached to the housing;
The hearing aid according to any one of claims 1 to 10.   The hearing aid according to claim 11, wherein the substantially longitudinal axis is defined by a line connecting the first microphone port and the second microphone port.   The hearing aid according to any one of claims 1 to 12, wherein the windshield cover extends substantially entirely around the hearing aid housing except for a gap opening formed between both ends of the windshield cover. A microphone mouth and a sound passage channel for guiding sound from the surroundings to the microphone mouth, the first dimension of the cross section of the sound passage channel is in the range of 0.15 mm to 0.5 mm, and the cross section of the sound passage channel The second dimension is at least 2 mm and the length of the sound passage channel is at least 1 mm;
A hearing aid suitable for suppressing wind noise.   The hearing aid according to claim 14, wherein the length of the sound passage channel is longer than 1 mm and shorter than 3 mm.   16. A hearing aid according to claim 14 or 15, wherein the second dimension is at least 3 mm.   A hearing aid according to any one of claims 14 to 16, wherein the first dimension of the cross section of the sound passage channel is in the range of 0.20 mm to 0.35 mm.   18. A hearing aid according to any one of claims 14 to 17, wherein the second dimension of the cross section of the sound passage channel is at least 5 mm.   A hearing aid according to any one of claims 14 to 18, wherein the sound passage channel is formed as part of an insert configured to receive electronic circuit components within the hearing aid housing.   The hearing aid according to any one of claims 14 to 19, wherein the sound passage channel comprises at least one bend that increases the length of the sound passage channel.

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