Patent Application
20080165996
The present invention relates to a waterproof hearing aid in which a waterproof structure is provided at the sound inlet of a microphone, at the sound outlet of an earphone, and at other locations.
To a hearing aid wearer, it is desirable that a hearing aid can be worn under any circumstances. For example, in the case where the wearer swears as a result of a proper amount of exercise, in the case where the wearer bathes at an unfamiliar place such as a sports center, or in other cases, it is desirable that the wearer do not take off his/her hearing aid because of a need for sufficiently obtaining information through his/her acoustic sense. In such circumstances, however, the hearing aid wearer presently takes off his/her hearing aid or wears it while caring about whether the hearing aid fails due to the entry of sweat or water.
In such a situation, as a waterproof structure for an ear-hang type hearing aid, a structure has been known in which a waterproof film holding member that holds a nonporous waterproof film is arranged in front of the sound inlet of a microphone, by which the enclosed state of a microphone chamber formed by the waterproof film holding member and a microphone case is improved (for example, refer to Patent Document 1).
Also, as a waterproof structure for an ear-insertion type hearing aid, a structure has been known in which a holed cap can be attached to a sound outlet connecting part of a hearing aid, and a microporous film made of non-tacky polytetrafluoroethylene is provided in the cap so that sounds can be transmitted easily and also earwax, moisture, sweat, and the like can be prevented from entering into the hearing aid from the auditory canal (for example, refer to Patent Document 2).
Further, a hearing aid has been known in which, a protective device using a nonporous diaphragm, which is formed of a material having a high sound propagation property such as titanium of 0.01 mm or thinner, in place of the microporous film is provided at a sound inlet opening and a sound outlet opening (for example, refer to Patent Document 3).
Patent Document 1: Japanese Patent No. 2869505
Patent Document 2: European Patent No. 0310866
Patent Document 3: Japanese Patent Application Publication No. 10-126897
However, in the waterproof structure of the hearing aid described in Patent Documents 1 and 3, the sound opening is covered with the nonporous waterproof film or the nonporous diaphragm, so that a sound entry pathway into the microphone (microphone chamber) and a sound exit pathway from an earphone (earphone chamber) become in an hermetically-sealed state, respectively. In such an enclosed state, if the air pressure or temperature on the outside of the hearing aid changes, a difference in air pressure arises between the inside and the outside of the enclosed space, and a pressure caused by this difference in air pressure acts on the waterproof film etc., by which a high tension is produced on the waterproof film. As the result, the acoustic impedance of the waterproof film etc. increases suddenly, and the attenuation of sound pressure caused by the waterproof film etc. increases, which poses a problem in that the sensitivity as a hearing aid decreases greatly.
Also, if the microporous film is used as described in Patent Document 2, the difference in air pressure does not arise, but the hearing aid of this type has a disadvantage that the hole in the film is easily clogged with earwax etc. Also, the microporous material formed of polytetrafluoroethylene has a larger specific gravity than a nonporous polyurethane elastomer material, and for this microporous material, if the film is made thin, the waterproof performance thereof decreases, so that it is difficult to sufficiently decrease the surface density of film, which poses a problem in that it is difficult to sufficiently decrease the acoustic impedance of film.
The acoustic impedance of film is substantially determined by the acoustic stiffness thereof in a frequency zone lower than the first resonance frequency of film. The acoustic stiffness of a circular film is proportional to the tension of film and inversely proportional to the biquadrate of film diameter. Especially in the case of the ear-insertion type hearing aid, the diameter of waterproof film is about 2 mm from the viewpoint of design. If the film diameter decreases, the variation in film acoustic impedance with respect to the change in film tension increases suddenly. Thus, for the waterproof hearing aid, it is important to adjust the air pressure on the inside and the outside of the film so as to be in equilibrium to prevent the film tension from changing.
The present invention has been made to solve the above-described problems with the related art, and accordingly an object thereof is to provide a waterproof hearing aid capable of being worn without caring about the entry of sweat or water even at the time of sweating or bathing.
To solve the above problems, the invention according to aspect 1 provides a waterproof hearing aid having a first waterproof film stretchingly provided at the sound inlet of a microphone and a second waterproof film stretchingly provided at the sound outlet of an earphone, includes a first ventilation means communicating a microphone chamber formed by the first waterproof film and the microphone with a hearing aid case chamber formed by a hearing aid case, a second ventilation means communicating an earphone chamber formed by the second waterproof film and the earphone with the hearing aid case chamber, and a third ventilation means communicating the hearing aid case chamber with the outside.
The invention according to aspect 2 is characterized in that in the waterproof hearing aid described in aspect 1, the first ventilation means is configured by a tube projecting into the hearing aid case chamber, a ventilation hole provided in the side wall of a tube forming a part of the microphone chamber, a permeable porous tube forming a part of the microphone chamber, or a ventilation hole provided in a microphone case.
The invention according to aspect 3 is characterized in that in the waterproof hearing aid described in aspect 1 or 2, the second ventilation means is configured by a tube projecting into the hearing aid case chamber, a ventilation hole provided in the side wall of a tube forming a part of the earphone chamber, or a permeable porous tube forming a part of the earphone chamber.
The invention according to aspect 4 is characterized in that in the waterproof hearing aid described in aspect 1, 2 or 3, the third ventilation means uses a porous film that allows a gas such as air to pass through, and is difficult to let a liquid such as water pass through easily.
The invention according to aspect 5 is characterized in that in the waterproof hearing aid described in aspect 1, 2, 3 or 4, the first waterproof film and the second waterproof film can be replaced freely.
As described above, according to the invention described in aspect 1, the first ventilation means communicating the microphone chamber with the hearing aid case chamber, the second ventilation means communicating the earphone chamber with the hearing aid case chamber, and the third ventilation means communicating the hearing aid case chamber with the outside are provided. Therefore, since the microphone chamber and the earphone chamber are in air communication with the outside, even if the outside air pressure or temperature changes, a difference in pressure between the hearing aid case chamber and the outside does not arise, and therefore a high tension is not produced on the waterproof film, so that a problem can be prevented in that the acoustic impedance of waterproof film increases suddenly, and the attenuation of sound pressure due to the waterproof film increases, thereby decreasing the sensitivity as a hearing aid greatly.
According to the invention described in aspect 2, the microphone chamber and the hearing aid case chamber can be made in air communication with each other easily. Therefore, the equilibrium of air pressures between the microphone chamber and the hearing aid case chamber is achieved smoothly.
According to the invention described in aspect 3, the earphone chamber and the hearing aid case chamber can be made in air communication with each other easily. Therefore, the equilibrium of air pressures between the earphone chamber and the hearing aid case chamber is achieved smoothly.
According to the invention described in aspect 4, the outside and the hearing aid case chamber can be made in air communication with each other easily without the entry of a liquid such as water into the hearing aid case chamber. Therefore, the equilibrium of air pressures between the outside and the hearing aid case chamber is achieved smoothly.
According to the invention described in aspect 5, the first waterproof film and the second waterproof film can be cleaned or replaced easily.
Embodiments of the present invention will now be described with reference to the accompanying drawings.
As shown in
As shown in
In the case of a custom-made hearing aid in which the shell 1 is manufactured by making a model of ear of the hearing aid wearer, as shown in
As shown in
The battery cover 8 is formed with a through hole 23 that causes the outside and the interior of the hearing aid case 3 (a hearing aid case chamber 22) to communicate with each other, and a cap 25 stretchingly provided with a porous film (third ventilation means) 24 engages with the through hole 23. Further, the battery cover 8 is mounted with an O-ring 26, so that when the battery cover 8 is made in a closed state, a waterproof structure such that water etc. do not enter into the hearing aid case chamber 22 is formed.
By using an elastic high-molecular film, for example, formed of polyurethane elastomer having a thickness of about 0.01 mm as the waterproof film 16, the acoustic impedance of the waterproof film 16 can be decreased to a value negligible with respect to the input acoustic impedance of the microphone 4. Thereby, almost the same sense of wearing as in the case where the waterproof film 16 is not mounted can be obtained because the sound pressure applied to the microphone 4 scarcely attenuates even if passing through the waterproof film 16.
As shown in
Also, as the waterproof film 19 as well, an elastic high-molecular film, for example, formed of polyurethane elastomer having a thickness of about 0.01 mm same as that of the waterproof film 16 is used, by which the acoustic impedance of the waterproof film 19 can be decreased to a value negligible with respect to the output acoustic impedance of the earphone 11. Thereby, almost the same sense of wearing as in the case where the waterproof film 19 is not mounted can be obtained because the sound pressure delivered from the earphone 11 to the external auditory canal scarcely attenuates even if passing through the waterproof film 19.
As shown in
The waterproof chip 17 and the waterproof chip 20 engage with the face plate 2 or the shell 1 merely by utilizing elasticity, so that these chips 17 and 20 can be removed easily by using tweezers, and therefore can be replaced with new ones. That is to say, the waterproof film 16 can be replaced freely because the waterproof chip 17 can be replaced freely, and the waterproof film 19 can be replaced freely because the waterproof chip 20 can be replaced freely.
Also, as shown in
As shown in
As shown in
In the microphone 4, the back electrode electret 32 is formed with one or a plurality of holes (back electrode holes) 32a to obtain satisfactory characteristics, and generally, the vibrating film 31 is also formed with a small hole (film ventilation hole) 31a. Therefore, the vibrating film front chamber 34 and the vibrating film rear chamber 35 communicate with each other, and the air pressures in the vibrating film front chamber 34 and the vibrating film rear chamber 35 are in equilibrium.
Also, as shown in
The sound pressure produced in the vibrating plate front chamber 46 by the vibration of the vibrating plate 41 passes through the sound outlet 48, the earphone chamber 21, and the waterproof film 19, and is propagated to the outside (external auditory canal). The edge part of the vibrating plate 41 is surrounded by a flexible high-molecular film 51, and the vibrating plate 41 is attached to the inner wall of the earphone case 40 via the high-molecular film 51. The high-molecular film 51 is formed with a small ventilation hole 51a. Therefore, the vibrating plate front chamber 46 and the vibrating plate rear chamber 47 communicate with each other, and the air pressures in the vibrating plate front chamber 46 and the vibrating plate rear chamber 47 are in equilibrium.
As shown in
If the time required for the equilibrium of air pressures becomes about 10 seconds or longer, the difference in air pressure between the interior of the hearing aid case chamber 22 and the outside, which is caused by an abrupt change in air pressure produced in an elevator or the like, does not disappear rapidly. Therefore, the sensitivity of hearing aid decreases, and therefore the hearing aid wearer feels difficulty in hearing.
Therefore, it is desirable that the air pressure in the hearing aid case chamber 22 become in equilibrium with the air pressure on the outside in a period of time as short as possible without sacrificing the waterproofness.
Also, it is desirable that the third ventilation means for ventilation between the hearing aid case chamber 22 and the outside be provided at a plurality of different locations. This is because if the third ventilation means is provided at one location only, although sufficient permeability is secured usually, the equilibrium of air pressures may be lost due to clogging of the porous film 24 with waterdrops or the like. If a plurality of the third ventilation means are provided, the possibility of all of the porous films 24 being clogged with waterdrops is lower than the case where third ventilation means is provided at one location.
Next, as another embodiment of the first ventilation means, as shown in
Also, as shown in
Also, by using a porous polytetrafluoroethylene resin made tube etc. in place of the rubber tube 56, the equilibrium of air pressures between the microphone chamber 18 and the hearing aid case chamber 22 can be achieved without forming the ventilation hole in the side wall of tube. The ventilation hole for the equilibrium of air pressures between the microphone chamber 18 and the hearing aid case chamber 22 may be provided at any location or at a plurality of locations.
Next, as another embodiment of the second ventilation means, as shown in
Next, as another embodiment of the third ventilation means, as shown in
If the ventilating ability between the microphone chamber 18 and the hearing aid case chamber 22 and the ventilating ability between the earphone chamber 21 and the hearing aid case chamber 22 are too high, and therefore the acoustic impedance is too low in the audio frequency band, the acoustic systems of the microphone chamber 18, the earphone chamber 21, the hearing aid case chamber 22, and the external auditory canal interfere with each other, whereby a problem concerning the hearing aid characteristics may be posed.
Therefore, these ventilating abilities are determined so that the equilibrium of air pressures is achieved in a period of time as short as several seconds or shorter, and the acoustic impedance is high to a degree such that a change in characteristics is negligible as compared with the case where no ventilation means is provided. For the tube (first ventilation means) 27 and the tube (second ventilation means) 28 shown in
According to the present invention, there is provided a waterproof hearing aid capable of being worn without caring about the entry of sweat or water even at the time of sweating or bathing. Therefore, the waterproof hearing aid becomes easy to handle, so that a demand for the waterproof hearing aid can be increased.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-045339 | Feb 2005 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP06/00986 | 1/24/2006 | WO | 00 | 8/22/2007 |
