JPH04175097A - Acoustic reproducing device - Google Patents

Abstract

PURPOSE:To enable a listner to listen to clear and high fidelity sound by constructing an acoustic tube so that one end of it is an ear attachment and the other end is a non-reflection end and providing an acoustic resistance control means on the back side of a speaker unit. CONSTITUTION:An earphone device mainly consists of an acoustic tube 1, a speaker unit 2 to be attached with its sound emitting surface 2a facing the inside of the tube and a sound resistance tube 6 serving as the acoustic resistance control means provided on the back side of the speaker unit 2. The acoustic tube 1 is formed so that its inner diameter W equals to that Wo of an external ear path A and attached with a ear attachment member 4 used for attaching its one end to an entrance C of the external ear path A. The other end of the acoustic tube 1 is formed with the non-reflection end and formed so that it has the same inner diameter as that W and has more or less a longer length. The acoustic resistance tube 6 is formed so that its one end opposite to the side of the speaker unit is open and that it has a more or less longer length.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sound reproduction device used as an earphone device, a headphone device, or a hearing aid.

[Summary of the invention]

The present invention includes an acoustic tube formed to have an inner diameter substantially the same as that of the external auditory canal, and a speaker unit that is attached to one side of the acoustic tube with its sound emitting surface facing inward of the tube. By forming the auricle attachment part, the other end serving as the non-reflecting end for sound, and providing acoustic resistance control means on the back side of the speaker unit, the sound emitted from the speaker unit reaches the eardrum and can be heard. After this, the sound reflected by the eardrum is prevented from being reflected back to the eardrum side and is not heard, and the air at the back of the speaker unit is made to flow viscously, thereby reducing the vibration of the diaphragm that makes up the speaker unit. The present invention is a sound reproduction device that can lower the lowest reproduction frequency of the speaker unit and obtain flat sound pressure frequency characteristics.

[Conventional technology]

2. Description of the Related Art Various types of sound reproduction devices, such as so-called earphone devices, in which a speaker unit or the like is attached to a person's auricle, have been proposed in the past, and are widely used for music reproduction and hearing aids.

In this conventional sound reproduction device, for example, when a user listens to sound using an earphone device, the sound reproduced from the speaker unit passes through the earphone housing and the ear canal, reaches the eardrum, and is heard by vibrating the eardrum. .

By the way, in the above-mentioned earphone devices, etc., the sound that reaches the eardrum is reflected by the eardrum and tries to go out through the auditory canal. However, in the conventional earphone devices, etc. Since the earphone housing is attached near the auricle in this way, sound that attempts to go out of the ear canal is reflected by the earphone housing and the speaker unit inside it, and then re-enters the ear canal toward the eardrum. That will happen.

Therefore, in the conventional earphone device described above, the user listens to the sound that is directly incident on the eardrum from the speaker unit and the sound that is reflected by the eardrum and then reflected again by the earphone housing or the speaker unit. When the time interval between these two sounds is less than several hundred μSeC, the so-called intra-head localization phenomenon or oppressive sensation occurs in the auditory sense, so that the sound cannot be heard as a good reproduced sound.

Therefore, in order to prevent the sound reflected by the eardrum from being reflected again by the earphone housing or the like, the present applicant proposed a sound reproduction device using an acoustic tube in Japanese Patent Laid-Open No. 2-86296. That is, this sound reproduction device includes an acoustic tube formed to have an inner diameter substantially the same as that of the external auditory canal, and a speaker unit mounted on one side of the acoustic tube with a sound emitting surface facing inward of the acoustic tube. , one end of the acoustic tube serves as an auricle attachment part, and the other end serves as a non-reflective end for sound. Therefore, in this sound reproduction device, the sound emitted from the speaker unit passes through the acoustic tube and reaches the eardrum, and after being heard at the eardrum, it is reflected to the non-reflection end side of the acoustic tube. It is reflected back to the eardrum and is not heard again.

[Problem to be solved by the invention]

By the way, the speaker unit used in such a sound reproduction device vibrates the diaphragm that constitutes the speaker unit in the front direction and back direction with respect to the sound emitting surface, thereby changing the air pressure and producing sound. It is made to occur. Therefore, the characteristics of the speaker unit are greatly influenced by the state of the air existing around the diaphragm.

In the sound reproducing device configured as described above, the rear surface of the speaker unit has a small internal volume, and the speaker mounting area is sealed by a member. Therefore, when installing this speaker, there is air within the component whose flow is restricted. This air expands and compresses due to the vibration of the diaphragm constituting the speaker unit, and acts as an elastic body on the diaphragm, thereby changing the lowest reproduction frequency of the speaker unit to a higher frequency side.

Therefore, when trying to listen to sound using such a sound reproduction device, since the minimum reproduction frequency of the speaker unit is high, low frequency sound cannot be obtained and good sound cannot be heard.

In addition, in such a sound reproduction device, in order to eliminate the inconvenience caused by the back side of the speaker unit being sealed, if the back side of the speaker unit is opened,
Sound leaks outward. In particular, when configured as a hearing aid, sound leaking to the outside is collected by a microphone, causing so-called howling.

Therefore, the present invention was proposed in view of the conventional situation, and after the sound emitted from the speaker unit reaches the eardrum and is heard, the sound reflected by the eardrum is transmitted again. This prevents sound from being reflected to the eardrum and being heard, and also prevents sound from leaking to the outside.
This was proposed for the purpose of providing a sound reproduction device that can lower the minimum reproduction frequency of the speaker unit and obtain flat sound pressure frequency characteristics.

[Means to solve the problem]

In order to achieve the above-mentioned problems, the sound reproducing device according to the present invention includes an acoustic tube formed to have an inner diameter substantially the same as that of the external auditory canal, and one side of the acoustic tube with a sound emitting surface facing inside the acoustic tube. The sound tube has one end serving as an auricle attachment part, the other end serving as a non-reflecting end for sound, and an acoustic resistance control means on the rear side of the speaker unit. It is characterized by being provided with.

[Effect]

In the present invention, since the inner diameter of the acoustic tube is made substantially the same as the external auditory canal, the acoustic impedance is not changed even when the sound reflected by the eardrum exits from the external auditory canal and enters the acoustic tube. In addition, since the other end of the acoustic tube is a non-reflective end, the sound that has gone out of the auditory canal and entered the acoustic tube will be reflected back toward the eardrum at the other end of the acoustic tube. is prevented.

Furthermore, since the acoustic resistance control means is provided on the rear side of the speaker unit, the air on the rear side of the speaker unit flows viscously as the diaphragm that constitutes the speaker unit vibrates.

Therefore, the diaphragm is not subjected to elastic action by the air at the back of the speaker unit, and the speaker unit exhibits a low minimum reproduction frequency. In addition, the vibration of the diaphragm is suppressed to some extent by the viscosity of the air at the back of the speaker unit, so the diaphragm does not resonate significantly even at the resonant frequency, and the speaker unit has a flat sound pressure frequency characteristic. show.

〔Example〕

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

First, a case where the sound reproducing device according to the present invention is configured as an earphone device will be described with reference to FIG.

This earphone device includes a sound tube (1) and a sound tube (1).
) The main components are a speaker unit (2) that is mounted with the sound emitting surface (2a) facing inward of the tube, and an acoustic resistance tube (6) that serves as an acoustic resistance control means provided on the back side of the speaker unit. be done.

The acoustic tube (1) is formed to have an inner diameter (W) substantially the same as the inner diameter (WO) of the external auditory canal (A). This acoustic tube (1) serves as an earphone housing, and is configured as a long tubular body having a uniform inner diameter (W). This sound tube (1
) acts as a sound path, and as mentioned above, the inner diameter (W) of the acoustic tube (1) is the inner diameter (A) of the external auditory canal (A).
The reason why the diameter is set to be substantially the same as that of the acoustic tube (No. 1) is to make it substantially the same as the acoustic impedance of this acoustic tube (1).

If the impedance of the acoustic tube (1) is made approximately the same as the impedance of the ear canal, the impedance generated when the sound reflected by the eardrum (B) exits from the entrance (C) of the ear canal (A) can be reduced. It is possible to prevent the sound from being reflected due to the change, and it is possible to prevent the sound from entering the external auditory canal (A) again. Therefore, the inner diameter (W
) may be the same as the average inner diameter of the human ear canal (A). The average inner diameter (No.) of the external auditory canal (A) of a human adult is said to be about 7.5 mm. Therefore, by setting the inner diameter (W) of the acoustic tube (1) to 6 mm to 9 mm, the difference in cross-sectional area between the acoustic tube (1) and the entrance to the external auditory canal (C) can be kept small, and reflections can be eliminated and the Good acoustic characteristics can be obtained by preventing the generation of waves and preventing reflected sound from reaching the eardrum (B).

On the other hand, the other end of the acoustic tube (1) is a non-reflective end of sound. In other words, this acoustic tube has the same tube length or the same inner diameter (W
) and is formed to be somewhat long.

In this way, by making the acoustic tube the same inner diameter and making it a certain length, the reflected sound is attenuated before reaching the other end,
It is designed to prevent reflections occurring at the other end of the acoustic tube.

Next, the acoustic tube (1) has one end facing the external auditory canal (A).
an auricular attachment member (for attaching it to the entrance (C) of the
4) is installed. This auricle attachment member (4) is made of flexible synthetic resin, rubber, or the like, and is intended to improve the feeling of attachment to the auricle (D). The inner diameter of this mounting member (4) is also designed so as not to change the acoustic impedance characteristics within the acoustic tube.

Then, a speaker unit (2) is attached to the negative side of the acoustic tube (1) so that the sound emitting surface (2a) faces the inside of the tube.

It is desirable that the speaker unit (2) be installed so as not to change the inner diameter (W) of the acoustic tube (1) so as not to disturb the impedance of the acoustic tube (1).

This speaker unit (2) is configured with a diaphragm, a voice coil for vibrating the diaphragm, and a magnetic circuit as the main components. That is, a driving current corresponding to the acoustic signal is supplied to the voice coil, and the diaphragm is driven in the front direction and the back direction with respect to the speaker sound emitting surface (2a), thereby performing sound reproduction.

Further, in this earphone device, an acoustic resistance tube (6) serving as acoustic resistance control means is provided on the back side of the speaker unit (2). This sound tube resistance tube (6) is open at the end opposite to the speaker unit and is formed to be long to some extent, so that the vibration of the diaphragm causes the air on the rear side of the speaker to flow viscously. . Therefore, the diaphragm is not elastically affected by the air at the back of the speaker unit (2), and its vibrations are suppressed to some extent by the viscosity of the air at the back of the speaker unit, so it resonates strongly at the resonant frequency. Never. As shown by the solid line (A) in FIG. 2, the lowest reproduction frequency of the speaker unit (2) is lowered and a flat sound pressure frequency characteristic is realized. In addition, in Figure 2, the dotted line (B) indicates the acoustic resistance tube (6) on the back side.
This shows the sound pressure frequency characteristics of a speaker unit that is not equipped with.

Furthermore, the acoustic resistance tube (6) serves as an acoustic resistance control means.
Since this attenuates the sound emitted to the rear side of the speaker unit (2), it is also possible to suppress the generation of standing waves on the rear side of the speaker unit (2).

In the sound reproduction device configured as described above, the sound reflected by the eardrum is not reflected again and is heard, and the speaker unit (2) has a low minimum reproduction frequency and a flat sound pressure frequency. Because it shows the characteristics, you can hear clear and high-fidelity audio.

Further, in this sound reproducing device, in order to achieve miniaturization of the -layer, a sound absorbing material may be arranged in the acoustic tube and the acoustic resistance tube.

That is, as shown in FIG. 3, this earphone device, like the earphone device described above, includes an acoustic tube (1), a speaker unit (2) mounted with the sound emitting surface facing inward of the acoustic tube, and a speaker unit. It is composed of an acoustic resistance tube (6) provided on the back side of the.

In this earphone device, the acoustic tube (1
) and one end of the acoustic resistance tube (6) opposite to the speaker unit (2) are provided with sound absorbing materials (5), (7) such as porous materials or cotton-like members. . That is, the sound absorbing materials (5) and (7) are used to achieve early sound attenuation.

Therefore, in the sound reproduction device configured in this way, even if the lengths of the acoustic tube (1) and the acoustic resistance tube (6) are shortened, the sound reflected by the eardrum will not be reflected again, as in the earphone device described above. Also, the lowest reproduction frequency of the speaker unit (2) is lowered,
A flat sound pressure frequency characteristic can be achieved. That is, the earphone device can be made smaller.

Further, the sound reproduction device according to the present invention can also be applied to a hearing aid.

An example of an earhook-type hearing aid will be explained based on FIG. 4. First, the acoustic tube (1) and the acoustic resistance tube (6) are connected to the pinna (D
) and bend it so that it follows the outer periphery of the At this time, the speaker unit (2) is partially attached to the acoustic tube (1) so that the sound emitting surface does not face the eardrum. That is, this is to prevent the generation of standing waves caused by repeated reflections of reproduced sound between the eardrum and the diaphragm of the speaker unit (2).

Next, the microphone (8) is configured to collect sound very similar to the sound collected by the pinna (D).
The acoustic resistance tube (6) is positioned near the auricle (D).
).

In a hearing aid configured as shown in Fig. 4,
The sound collected by the microphone (8) is converted into an acoustic signal by the microphone (8). This acoustic signal is then supplied to the speaker unit (2) via an amplification device (not shown), and by driving this speaker unit (2), the sound collected by the microphone (8) is transmitted to the outside. Acoustic tube (1)
) is emitted into the ear canal.

In addition, when this sound reproduction device is configured as a hearing aid,
If a sound absorbing material is used at the end of the acoustic resistance tube (6) opposite to the side where the speaker unit (2) is arranged, the reproduced sound emitted to the back side of the speaker unit (2) can be further attenuated. This prevents the reproduced sound emitted from the speaker unit (2) from being collected by the microphone (8), and the speaker unit (2)
Howling occurring between the microphone (8) and the microphone (8) can be prevented.

In addition, when the sound reproduction device according to the present invention is configured as a hearing aid, a microphone (8
) is preferably provided at a position close to the eardrum when the hearing aid is worn on the auricle.

Therefore, as shown in FIG. 5, the microphone (8) is
When the hearing aid is attached to the auricle (D), the concha cavity of the auricle (D)
E) It is desirable to arrange it so that it is located within.

That is, the microphone (8) is positioned at the entrance (A) of the acoustic tube (1) to the concha cavity (E) of the auricle (D) when the hearing aid is attached to the auricle. C) is attached to the outer circumferential surface near where it is inserted. By providing the microphone (8) in this manner, it is possible to collect sound that is similar to the sound that is actually collected by the pinna of the ear, and a realistic hearing aid function can be achieved.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the inner diameter of the acoustic tube is made approximately the same as that of the external auditory canal, so that the impedance caused by the sound reflected by the eardrum being emitted from the external auditory canal to the outside of the external auditory canal can prevent changes in

Furthermore, since the other end of the acoustic tube is a non-reflective end, it is possible to prevent the sound emitted outside the ear canal from being reflected back to the eardrum side.

Therefore, when looking at the sound source from the entrance of the external auditory canal, it is possible to prevent reflections from the earphone housing and auricle on the sound source side, and prevent the auditory localization phenomenon in the head and the feeling of pressure when listening. be able to.

Furthermore, since acoustic resistance control means is provided on the back side of the speaker unit, the vibration of the diaphragm that makes up the speaker unit is controlled, so the speaker unit has a low minimum playback frequency and flat sound pressure frequency characteristics. It becomes possible to realize this.

Therefore, with such a sound reproduction device, it is possible to hear clear and high-fidelity sounds, and when configured as a hearing aid, it is possible to hear sounds that are faithful to external sounds. .

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing an example in which the sound reproduction device according to the present invention is used as an earphone device. FIG. 2 is a sound pressure frequency characteristic diagram of a speaker unit constituting the sound reproduction device according to the present invention. FIG. 3 is a schematic cross-sectional view showing another example in which the sound reproduction device according to the present invention is used as an earphone device. FIG. 4 is a perspective view showing an example in which the sound reproduction device according to the present invention is applied to a hearing aid, and FIG. 5 is a perspective view showing another example of the hearing aid. l...Acoustic tube 2...Speaker unit 4...Attachment member 6...Acoustic resistance tube 8...Microphone and earphone Figure 3

Claims (1)

[Scope of Claims] An acoustic tube formed to have an inner diameter substantially the same as that of the external auditory canal, and a speaker unit attached to one side of the acoustic tube with a sound emitting surface facing inward of the acoustic tube, The acoustic tube has one end serving as an auricle attachment portion, the other end serving as a sound non-reflecting end, and an acoustic resistance control means provided on the rear side of the speaker unit.