DK150779B - HEADLESS HEARING DEVICE - Google Patents

Description

, 150779

The present invention relates to a directional hearing aid having a directional microphone located in a housing having at least two spatially spaced sound inputs that are acoustically associated with spatially spaced sound apertures for the sound's entry into the hearing aid.

Such a hearing aid is known from German Patent Specification No. 1,487,565. The hearing aid described therein has a rearward opening opening with respect to a carrier of the hearing aid, which is connected to an input into a directional microphone over a channel. The directional microphone is placed immediately behind a forward or in the visual direction of the user of the hearing aid, so that leading-edge sound waves strike the diaphragm of the directional microphone with greater amplitude and sound correspondingly louder.

A further directional hearing aid is known from German Patent No. 721,670. The hearing aid described therein has a directional microphone, the membrane of which is usually simultaneously connected to the surroundings. By means of a plate, the diaphragm is unilaterally detachable from the surroundings, so that the directional microphone receives reception properties like a normal non-directional microphone.

All of these known hearing aids have in common that they have their optimum reception sensitivity in a single predetermined direction which cannot be changed.

The directional dependence of the hearing is now influenced not only by the directional sensitivity of the hearing aid used, but also by the ear's hearing ability and the shape of the head of a person wearing a hearing aid so that a directional hearing aid gives a person a satisfactory directional dependence on the hearing, while not capable of doing so by another person.

In order to meet the hearing requirements of any user, it is highly desirable to provide a hearing aid with adjustable directional sensitivity which allows the user to adjust the directional sensitivity of his hearing to his own needs.

The object of the present invention is to provide a directional hearing aid whose directional sensitivity is adjustable.

According to the invention, this is accomplished by a hearing aid of the kind initially provided, which is peculiar to an adjusting means for changing the effective phase shift between the sound inputs for sound emitted from a common sound source.

This adjusting device according to the invention enables, at one given orientation of the hearing aid to a sound source, to adjust the phase shift between the two sound waves which reach the directional microphone through the sound inputs of the hearing aid, so that the two sound waves at the location of the directional microphone's membrane can be added freely. that is, the sound source is heard at maximum volume, or subtracted, ie, the sound source is heard at minimum volume. Also, all intermediate settings are possible so that the directional sensitivity of the hearing aid is continuously adjustable.

Advantageous further designs of the hearing aid are specified in the subclaims.

The hearing aid according to the invention makes it possible to distinguish from a preferred direction sound from echo and sound and other noise from other direction. The invention enables setting of the directional characteristics desired at all times, minimizing feedback noise conditional noise and avoiding distortions caused by the user's head.

The invention will now be explained in more detail with reference to the drawing, in which fig. 1 shows a sketch for explaining the function of the invention; FIG. 2a to e have different polar characteristics useful in explaining the apparatus of the invention; 3 is a drawing showing a hearing aid mounted in glasses for explaining important features of the invention; FIG. 4a and 4b show the top of a human head with a hearing aid arranged on the head to explain the sensitivity balance idea of the invention; 5 is an isometric view of an embodiment of the apparatus according to the invention, where the distance between the apertures of the hearing aid is adjustable; 6 is a side view of the structure of FIG. 5, FIG. 7 is a modification of the apparatus of FIG. 5, FIG. 8 is a vertical sectional view, partly in section, of a hearing aid, the directional effect being adjustable by means of a blade or port and the openings facing outwards; FIG. 9a and 9b are drawings useful in explaining the function of the embodiment of FIG. 8, FIG. Fig. 1 was a hearing aid for placement behind the ear and where flexible tubes extend from the microphone openings outward to the hearing aid housing; 11 shows a microphone in which the size of the cavity is varied to change the direction of the microphone; and FIG. 12 the microphone of FIG. 11 located in the hearing instrument housing.

It will be appreciated that the present invention is generally applicable to hearing aids of the types for placement behind the ear, for placement in the ear, for mounting in glasses and other types of head worn, as will be described in more detail below.

At this point, a brief explanation of certain theoretical considerations contained herein seems desirable. It will be noted in the various figures that similar reference numerals refer to similar elements.

It will be understood that the following explanation is generally applicable. The different distances, times and directions are approximate and are stated for the sake of explanation, but should not in any way be considered limiting.

Pig. 1 shows a head-mounted hearing aid 11 which may be of the type for placement behind the ear or for mounting in glasses, see also fig. .3.5 and lo. The microphone capsule 12 in the hearing aid 11, see FIG.

3, has two physically separate sound apertures labeled A and B corresponding to apertures 18 and 20 of FIG. 5 · The circular arc 43 of FIG. 1 shows at one point the location at the opening A of an information bit derived from a sound source # 1 located in a frontal direction (about 0 ° incidence) relative to the carrier. 14.2 mm further away from source # 1 at the position of aperture B as indicated by the dashed circular arc 45, the same information bit passes 4, 4 microseconds later. The microphone 12 perceives the difference as an audio signal from the preferred direction and produces a full output signal.

In another case, an information bit arrives at a point from a disturbing sound source # 2 located in this example in a backward direction (about 180 ° incidence) first at opening B as indicated by a circular arc 47 and then about 4, 4 microseconds later at aperture A as indicated by the dotted circular arc 49- The microphone 12 perceives this time difference as an undesirable signal and produces a minimum output signal.

The microphone 12 provides the foregoing functions in that it has a built-in time delay of 41.4 microseconds, thereby delaying the sound wave pressure coming in through opening B 41.4 microseconds, and causing a subtraction of the sound pressure coming in through opening B, from the sound pressure coming in through opening A.

In the previous example of sound coming from source # 1, the sound pressure at aperture B, subtracted from the sound pressure coming in at aperture A, is effectively at aperture A approx. 82.8 microseconds earlier. Thus, the sound pressures are not the same and they do not cancel each other out, which is why an output signal appears.

In the previous example of sound coming from source no.

2, the sound arrives at aperture A 4l, 4 microseconds after it enters through aperture B. The same sound is delayed 4l, 4 microseconds by the microphone 12 so that equal pressure is subtracted and therefore abrogated.

To enable substantially complete uplift, the sound pressures that enter through the two openings in the microphone capsule must be the same in size. Thus, the coupling between the openings in the body of the hearing aid ll and the sound openings A and B in the microphone capsule 12 must affect both internal auditory pathways uniformly. The foregoing is most effective if the coupling paths resonate well beyond the frequency range in which the directional effect is desired.

Por angles out to the side of the 0 ° - 180 ° line of incidence, the time difference in motion between opening A and opening B is less than 4l, 4 microseconds. This results in less complete cancellation.

In FIG. 2a is shown the sound pattern record of one embodiment of a microphone with an effective opening distance of 14.2 mm, and this sound pattern is the known polar cardioid characteristic. The maximum sensitivity is found at 0 °, half of the maximum sensitivity (-6dB) occurs at approx. 9o ° and there is zero sensitivity at 18o °.

Pig. 2b shows polar characteristics based on an aperture distance of 27.4 mm; and FIG. 2c shows the polar characteristic based on an opening distance of 7.4 mm. The last two distances were chosen to achieve a difference of approx. 10B between 0 ° and 180 ° sensitivity and can be compared to the sensitivity obtained at a distance of 14.2 mm which provides the cardioid characteristic of FIG. 2a.

Accordingly, a basic feature of the invention is the setting of the directional effect of a hearing aid microphone combination to enable the user to adjust the received sound pattern and the range of minimal sensitivity.

In one form, the apparatus of the invention has at least two ports or access openings where the sound can reach the microphone and the microphone perceives the difference in time that it takes for a sound wave to move between these openings. As explained below, the directional effect can be set by using a construction which allows manipulation of them. effective sound opening distance. Adjusting the directional effect can also be achieved by adjusting the connection between two sound openings and the sound inputs. Another modification for adjusting the directional effect includes a microphone capsule which projects into two chambers which have adjustable spacings for audio input. A resilient support is used to support the capsule, and the support acts as a chamber divider.

According to the present invention, there is thus provided a hearing aid microphone combination which distinguishes sounds coming from different directions and makes the whole hearing device a more useful product and increases the acceptability of hearing aids. By using the hearing aid microphone combination according to the invention, it is possible to recognize sounds coming from a preferred direction with respect to the echo and rumble and other disturbing sounds arriving from other directions. According to the present invention, desirability characteristics are provided, as well as feedback noise is minimized and compensation for diffraction or distortion caused by the wearer's head.

Referring now to FIG. 3, which shows a hearing aid 11 for glasses 15 having a directional microphone capsule 12 disposed in a spectacle bar 17. The other known components of the hearing aid 11 comprising the receiver 14 can also be applied to the spectacle rod 17 in known manner. As mentioned above, a person wearing the hearing aid 11 wants to face the (visual) source of the primary sound in which he is interested, indicated by the arrow 13. According to the invention, the hearing aid 11 and the microphone capsule 12 provide improved and adjustable directional effect to allow the wearer to separate the desired sound source.

If the microphone capsule 12 is positioned so that the sound wave has free access to its sound aperture regions A and B in FIG. 1, such as by placing the capsule in an acoustically transparent housing, or by arranging the hay assembly structure such that the sound openings are located at the outside of the structure, the microphone capsule 12 will exhibit the directional characteristics for which the capsule is designed.

Referring now to FIG. 5 ° g 6. It has been found that the directional characteristics of the hearing aid can all be adjusted or varied by mounting the microphone capsule 12 in a small cavity or chamber 21 with the possibility of changing the phase of the sound wave supplied to the sound opening: preferably 18 and 20 (correspondingly to openings A and B in Fig. 1).

The cavity or chamber 21 may conveniently be formed in the eyeglass bar 17 or in the hearing aid type for placement behind the ear, see FIG. 7 and laughed. The cavity 21 is enclosed on all sides, one side as the closure element having a slidable element with an opening as explained below. The microphone capsule 12 is positioned in place between suitable insulating mounting pads 25, which serve not only to hold the microphone capsule in place, but also to effectively divide the cavity 21 into two separate sound spaces 27 and 29 for the reasons set forth below.

The microphone capsule 12 is electrically connected by means of wires 31 over an amplifier to the receiver 14 and other known components of the hearing aid 11, in the same manner as shown in FIG. lo.

A stationary panel or cover 23 disposed above the cavity 27 is suitably attached to the eyeglass bar 17, and a slidable panel or cover 28 is disposed above the cavity 29. The panel 23 has an opening which acts as a first or anterior audio input 24, and the panel 28 has an opening 26 which serves as a second or rear audio input 26. The panel 28 is movable relative to the panel 23, and the purpose of this movement is to adjust or adjust the distance between the openings 24 and 26. Relative to a 0 ° incident line is the entrance 26 located behind the entrance 24.

The pads 25 serve to mount the microphone capsule 12 to close any opening between the two cavities 27 and 29. The front opening 18 of the microphone capsule leads to or is acoustically interconnected with the front cavity 27 and the rear opening 2o of the micro 7. The audio cap 24 leads to or is acoustically coupled to the rear cavity 29. The audio input 24 leads to or is acoustically coupled to the front cavity 27, and the audio input 26 leads to or is acoustically coupled to the rear cavity 29.

With the above-described construction and the conditions stated, it is the distance between and location of the sound inputs 24 and 26, which are coupled respectively with the cavities 27 and 29, which determine the effective opening distance and not the physical distance between the microphone capsule openings 18 and 20 . The audio inputs 24 and 26 may be single large cuts in the eyeglass bar 17 which form part of the hearing aid housing or several small holes or slits in the hearing aid housing and may comprise even moderately long tubes connecting the cavity to the outside of the hearing aid housing, as explained with reference to FIG. lo.

Since the sound openings or inputs 24 and 26 can be set relative to each other by selectively controlling the distance between the sound openings 24 and 26, the directional characteristics of the combination of the hearing aid 11 and the microphone capsule 12 can be set or varied.

It should be noted that the openings 24 and 26 are shown facing outwards in FIG. 5 and 6 and in other figures for the sake of clarity of illustration. However, to reduce sweat and moisture which may penetrate through openings 24 and 26 into space 21 and to improve the dissipation of any sweat and moisture entering into cavity 21, openings 24 and 26 are in fact facing down. For cosmetic reasons, the openings 24 and 26 may also more suitably face downward.

The microphone openings 18 and 20 are sufficiently large that the openings have minimal impedance and do not introduce resonances or phase shifts that could destroy the directional characteristics of the hearing aid. However, high impedance openings can be used as long as the co-ordinations of the front cavity - anterior orifice and posterior cavity - posterior orifice are tuned so that the same amplitude changes are introduced at both locations.

As mentioned above, the directional effect of the microphone 12 in the hearing aid 11 is controlled by the separation of the inputs 24 and 26 which determine the effective opening distance. In general, the cardioid characteristics shown in FIG. 2a for a selected opening distance. As the effective opening distance is increased from the selected distance, a characteristic will be obtained, as indicated by the pole diagram in FIG. 2b. On the other hand, when the effective opening distance is reduced from the selected opening distance which provides a cardioid characteristic and approaches zero, the sensitivity decreases. The sensitivity at 180 ° will no longer be zero, and the microphone will not be substantially. direction-sensitive as indicated in FIG. 2c.

It has also been found that undesirable amplified sounds, e.g. Sounds that escape from the acoustic coupling to the ear including the earpiece 16 (see Fig. 3) or from the connections of the sound tube 18a connecting the earpiece to the hearing aid can be coupled as an acoustic feedback and re-amplified by the microphone capsule 12 thereby causing flute or whistle. . Such undesirable sounds appear to come from the approximate direction indicated by arrow 33 in FIG. Third

By adjusting the directional effect of the combination of hearing aid and microphone, a minimal sensitivity to sound coming from the approximate direction indicated by arrow 33 can be obtained to decrease or exclude the whistling or whistling sounds.

The aforementioned distortion or shadow effect caused by the human head on the normal sound patterns which affect a hearing aid placed on the head is shown in FIG. 4. If e.g. the microphone 12x is placed in the position indicated in FIG. 4a and 4b, it will have a minimal sensitivity to sound coming from the approximate direction indicated by arrow 21a. Adjusting the directional effect of the combination of the hearing aid 11 and the microphone capsule 12 to obtain minimal sensitivity to sound coming from the direction of Vlen 33 also tends to tune the minimum sensitivity to sound caused by the diffraction of the wearer's head.

As the head changes the directional sensitivity pattern, this means that the exact placement of the hearing aid on the wearer's head also affects the directional sensitivity pattern. is applied to the hair above the head and preferably near the forehead to provide a more symmetrical directional pattern than a hearing aid placed behind the ear. However, it is more common nowadays to place hearing aids behind the ear, in the ear or in glasses. In all cases, the invention enables the wearer or dealer or clinician to adjust the directional effect of any of the aforementioned types of head-mounted hearing aids, including the type for hair placement, to achieve the directional pattern desired by the individual wearer.

As mentioned above, such an adjustment will reduce feedback to reduce noise and also allow higher acoustic amplification, which is particularly critical in ventilated earpieces or open earpieces and will determine the direction of minimum zero or zero to reduce the reception of unwanted sounds from that direction. , which a 9 150779 particular user finds most unfortunate.

Such an adjustment furthermore allows, by a single hearing aid, to set the sound pattern sensitivity zeros so that the most symmetrical pattern around the center plane of the hearing aid is obtained. Pig. 2a shows the cardioid characteristic of the directional hearing aid itself, while FIG. 2d approximately shows the normal sensitivity of such a hearing aid when placed on a user's head. It should be noted that the characteristic is turned approx. 45 °> and that the zero value is not sharp.

In FIG. 2b for a hearing aid placed on the head, two distinct minima occur in the region at ca. 125 ° to 145 ° and 215 ° to 235 ° · When this headset is positioned on the head which has a diffraction diagram as shown in FIG. 2d, the sensitivity diagram shown in FIG. 2e. Thus, there are a number of variations in sensitivity characteristics. However, according to the invention, the feature is that regardless of the variations in the sound pattern, the user or dealer or clinician, respectively, can empirically adjust the directional effect of the combination of hearing aid and microphone to achieve the optimal sensitivity desired by the user.

It will also be appreciated from the foregoing that while the cardioid characteristic located on the 0 ° axis is indicated as desirable, when the user desires minimal sensitivity from a single direction, variations thereof can be obtained by correct setting and orientation of input and opening.

Another embodiment of the invention is shown in FIG. 7a showing a portion of a hearing aid of the type for placement behind the ear. The construction of FIG. 7 is substantially similar to the construction of the embodiment of FIG. 5 and 6. In FIG. 7, the microphone capsule 12 is mounted by means of mounting pads 25 in a cavity 21. The cover 21A of the cavity 21 extends over the entire length of the cavity and has a series of spaced holes or openings which act as sound openings and are generally designated 3o. Plugs or screws or other locking means 32 are selectively disposed in the holes 30 so that only selected holes remain open thereby adjustably adjusting the distance between the sound access openings or accesses to the respective cavities 27 and 29 and thus to the microphone capsule 12 and the sound openings 18 and 20.

FIG. 8 shows another embodiment of the invention having means for controlling the phase of the sound wave arriving at the sound opening regions 18 and 20 of the microphone capsule 12, see also FIG. 9a and 9b. The microphone capsule 12 is disposed in a cavity 21 on a suitable mounting pad 25A. The pad 25A is provided as a bottom and side support for the capsule 12, and a passage 4l remains open along the longitudinal direction of the capsule 150779 to acoustically connect the left and right regions 21A and 21B of the cavity 21.

Referring now to FIG. 9a and 9b for a brief explanation of the function of the structure of FIG. 8. When a wing 43 is fully open, as shown in FIG. 9a, the phase of the sound wave arriving at the microphone capsule 12 indicated by the direction of the arrow 13 represents a distance D1, so: shown in FIG. 9a. When the wing 43 is closed, the effective phase of the arriving sound wave is represented by the distance D2 in FIG. . Intermediate settings of the wing 43 produce intermediate phase shifts and intermediate directional characteristics for the combination of hearing aid and microphone.

Changing the position of the blade 43 in FIG. 8, more specifically, produces a change in directional sensitivity in the same way as the relative distance between the sound inputs 24 and 26 of FIG. 5 and 6 vary. Referring again to the polar characteristic curves of FIG. 2. Pig. 2c indicates e.g. when the wing 43 is in the open position shown in FIG. 9a> ie the microphone capsule 12 has a sensitivity diagram which is only slightly directional. As the wing 43 moves from its open position to its closed position shown in FIG. 9b, the directional sensitivity is gradually changed to the curve shown in FIG. 2b.

Referring again to FIG. 3 and 6 and FIG. 4. As mentioned, the combination of the hearing aid 11 and the microphone capsule 12 can be set to have a zero or minimum sensitivity to sound coming from any desired direction. Yed selective setting of that effect. Thus, at a minimum aperture distance (and the wing position of Fig. 8), a minimal sensitivity can be obtained for sound coming from a particular direction.

An advantage of such an adjustment is, as mentioned above, that the unwanted sounds which cause the aforementioned whistle can be effectively excluded, and furthermore, the entire hearing aid can be operated at a higher level of amplification to receive the desired sounds. A further advantage is that the sensitivity curve can be set so that the minimum sensitivity to sound coming e.g. from a particular direction, can be substantially aligned with the reduced sensitivity of sound coming from the direction indicated by arrow 21a (due to the aforementioned diffraction caused by the wearer's head) while maintaining maximum sensitivity for sound coming from a frontal or zero degree of incidence

The embodiment of the invention shown in FIG. 1o comprises a microphone capsule 12A which substantially corresponds to the microphone capsule 12 of FIG. 5, and mounted in a chamber 51 of a hearing aid 11 of the type for placement behind the ear. Pig. lO also shows, as small blocks, conventional hearing aid components including the amplifier, receiver and battery which are suitably connected in a well-known manner. The hearing aid 11 has a first or front sound opening 53 which is directly connected to the opening 18A of the microphone 12A over a flexibly stretchable tube 54. A flexible tube 59 is coupled to the rear sound opening 2oA. The free end of tube 59 forms a second or posterior opening 57 which faces upwardly and rotates approx. 9o in relation to the opening 53.

An acoustically transparent cover 64 is mounted to shield openings 57 and outward tube 59 to reduce wind noise, as well as to improve the cosmetic appearance of the hearing aid.

The front sound aperture 53 is positioned so that when the hearing aid is placed on the wearer's head that the 0 ° incident line 13 is substantially straight ahead of the wearer. The tube 59 is further adjustably pivotable about the rear opening 57 to provide mechanical adjustment of the distance between the openings 53 and 57.

The embodiment of the invention shown in FIG. 11 comprises a microphone capsule 12B disposed in a similar manner as shown in FIG. 5.6 and 7 In this embodiment, the setting of the directional effect of the combination of hearing aid and microphone housing is obtained by placing an adjustable phase shifter in the microphone capsule itself.

The front opening 18 of the microphone capsule 12B corresponds to the opening 18 of FIG. 5 and 6. The directional effect of the combination of hearing aid housing and microphone capsule is varied by means of an adjustable piston or plate 63 mounted by a resilient bellows 68 on the interior of the microphone capsule housing 62. An adjusting screw 7o protrudes from the capsule housing and is adjustable for moving the plate 63 into the microphone cavity 60 to change the size of the cavity. The setting of the acoustic volume of the cavity controls the phase shift or delay and thus regulates the directional effect of the combination of hearing aid and microphone.

The barometric pressure affects the phase shift produced by an acoustic impedance and a cavity. FIG. 11 thus shows a combination of hearing aid and microphone that is substantially independent of barometric pressure, using pressure-sensitive bellows 63 and 65 which carry a plate which changes the area or size of the opening of the rear audio port 2oB. As the barometric pressure rises, the bellows contract to seek to limit the gate 2oB and cause a higher acoustic impedance. However, as the barometric pressure decreases, the bellows expands to increase the effective aperture 2oB, thereby reducing the acoustic impedance.

Claims (10)

12 $ 15077 Patent Claim. A directional hearing aid with a directional microphone (12) arranged in a housing with at least two spatially spaced sound inputs (18,20, 18a, 20A) acoustically connected to spatially spaced sound apertures for the sound's entry into the hearing aid, characterized by an adjusting means (28 ; 30,32; 43; 57; 64,65,67,63,68,70) to change the effective phase shift between the audio inputs (18,20; 18A, 20A) for output from a common audio source. Hearing aid according to claim 1, characterized in that the adjusting means has an adjustable sound opening (26; 30; 57). Hearing aid according to claim 2, characterized in that the adjustable sound opening (26; 30) connects the surroundings to one of two cavities (27,29) in which an acoustic chamber (21) formed in the housing is divided by the directional microphone and its attachment - the second cavity being connected to the surroundings via a further sound opening (24). Hearing aid according to claim 2, characterized in that the adjustable sound opening (26) in its location is formed in a plate (28) which is displaceable on the housing (28). Hearing aid according to claim 3, characterized by,. that the adjustable sound opening in its location is formed by one of several sound openings. (.30), which can be selectively closed. Hearing aid according to claim 2, characterized in that the adjustable sound opening (57) in its position is formed at the • end of a swivel tube connected to a sound input (20) in the microphone. Hearing aid according to claim 1, characterized in that the adjusting means is designed for optional reduction of a passage path (41) formed between a rear cavity region (21B) and a front cavity region (21A) in which a chamber (21) the housing is divided by the attachment for the directional microphone (12). Hearing aid according to claim 7, characterized in that the adjusting means has a pivot-adjustable wing (43) arranged in the passage path. Hearing aid according to claim 1, characterized in that the adjusting means causes an acoustic phase shift at a sound input leading into a microphone cavity (60) in the microphone (12B). Hearing aid according to claim 9, characterized in that the adjusting means has means for changing the size of the sound system.