JPH01255898A - Breath current sensor - Google Patents

Abstract

PURPOSE:To reduce the cost and to improve the detection precision by providing a front air chamber in the front of a microphone and arranging plural sound holes connected to this chamber in a curved front plate. CONSTITUTION:A front air chamber 3b is provided in the front of a microphone 4, and plural sound holes 4a connected to this chamber 3b are arranged in a curved front plate 3a. Since the breath current reaches the microphone 4 from any sound hole 4a through the front air chamber 3b, plural sound holes 4a have the same function as plural microphones through the front air chamber 3b. Consequently, only one detecting microphone 4 is required, and an unnecessary band is easily eliminated because the front air chamber 3b and sound holes 4a constitute an acoustic high-cut filter. Thus, the constitution is simplified and the cost is reduced, and detection is surely performed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an expiratory airflow sensor used in vocal training machines and the like.

Conventional technology FIG. 5 shows a perspective view of a conventional expiratory flow sensor.

In the figure, 1 indicates a body case, and 2 indicates a sensor microphone. A plurality of microphones 2 are arranged approximately equally on the curved front plate 1a.

FIG. 6 shows an example of the use of this expiratory flow sensor. The exhalation flow sensor is useful for vocalization practice, such as pa-pi-bu-pe.
This is to detect whether the pop sound when uttering ``po'' etc. is being uttered normally.

Therefore, it is desirable that the setting position of the sensor has as little influence on the mouth as possible. For this purpose, a plurality of microphones 2 are arranged in a curved shape 1a.

FIG. 7 shows a partial cross-sectional view of the expiratory flow sensor in FIG. In the figure, each microphone 2 has a sound hole 2a formed in a front plate 1a. 2b is an output end of the microphone 2, and the respective output ends are electrically connected in parallel. As for the microphone 2, a compact and light-weight, for example, an electronic condenser microphone (ECM) is suitable. Therefore, this description uses ECM as an example.

Figure 8 is a simple equivalent circuit diagram of this expiratory flow sensor.
Specifically, it is a pressure type microphone.

In the figure, Po indicates the input sound pressure, and Z indicates the vibrating membrane of the microphone 2.

FIG. 9 shows an example of frequency characteristics of this sensor. As mentioned above, in order to detect the pump sound, it is necessary to detect an extremely low frequency range rather than the voice range, and an ECM that extends to the low frequency range can be said to be the most suitable microphone as an expiratory flow sensor.

Problems to be Solved by the Invention However, in the conventional exhalation flow sensor described above, it is necessary to arrange a plurality of microphones 2, resulting in a complicated configuration and an unavoidable increase in cost. Furthermore, the microphone 2 has the disadvantage that it is easy to detect unnecessary voice ranges other than the expiratory flow, other ambient noises, etc., and the circuit processing becomes complicated.

It is an object of the present invention to eliminate the above-mentioned drawbacks and to provide an excellent expiratory flow sensor that is inexpensive and has high detection accuracy.

Means for Solving the Problems In order to achieve the above-mentioned objects, the present invention provides a front air chamber at the front of a microphone, and a plurality of sound holes for venting to this air chamber are arranged on a curved front plate. It is.

Function The present invention has the following effects due to the above configuration. In other words, the multiple sound holes in the front air chamber have the same function as the multiple microphones, so only one detection microphone is required, and in addition, an acoustic high-cut filter can be configured with the sound holes in the front air chamber. Therefore, unnecessary bands can be easily removed.

Embodiment FIG. 1 is a partial sectional view showing an embodiment of the present invention. In the figure, 3 is a body case, 3a is a curved front plate, and 4 is a microphone, which has a front air chamber 3b at the front through a sound hole 4b. A plurality of sound holes 4a are formed in the.

4C is the output end of the microphone 4.

Next, the operation of the above embodiment will be explained. The exhaled airflow can reach the microphone 4 via the front air chamber 3b no matter which one of the sound holes 4a enters.

Therefore, acoustically, the movement is the same as when the microphone 4 is placed in the sound hole 4a. Moreover, the air mass Ma of the sound hole 4a and the air stiffness Sa of the front air chamber 3b have an acoustic high-frequency advantage, as shown in FIG.

The frequency characteristic at this time is as shown by the solid line 3A shown in FIG. 3, and it is possible to detect only the extremely low frequency range necessary as an expiratory flow sensor.

In this way, according to the above embodiment, since it is configured with one microphone, the configuration is simple and inexpensive, and the unnecessary band of the expiratory flow sensor can be configured with an acoustic cut filter, so detection can be ensured. can be done. Furthermore, it has the advantage that circuit processing can be simplified.

FIG. 4 shows an equivalent circuit diagram of another embodiment.

In this embodiment, the microphone 4 in FIG. 1 is a differential type microphone provided at the front and back of the diaphragm having a sound hole, and FIG. 48 is a general equivalent circuit diagram of this differential type microphone. It is.

POS-jkdcos (It indicates the sound pressure from the sound hole.

When this is configured as shown in FIG. 1, the air stiffness sb of the back air chamber 3C in the same figure is configured as shown in FIG. 4B. Therefore,
Since the sb is formed on the back of the microphone 4, the air stiffness is reduced and the sensitivity can be higher than when a pressure type microphone is used. The frequency characteristic in this case is as shown by the broken line 3B in FIG.

In the embodiment of the present invention, the sound holes are arranged on a curved front plate, but the same effect as the main idea can be obtained even if the front plate is flat. Similar applicability also applies to other types of microphones.

Effects of the Invention As is clear from the above embodiments, the present invention provides a microphone 4.
A front air chamber 3b is provided in the front part of the
The structure is simple and inexpensive, and detection is reliable because unnecessary bands can be removed by an acoustic high-cut filter. , it has the advantage that circuit processing can be simplified.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing one embodiment of the present invention, FIG. 2 is an equivalent circuit diagram of the same embodiment, FIG. 3 is a frequency characteristic diagram of the same embodiment and other embodiments, and FIG. 4 is a diagram of other embodiments. FIG. 3 is an equivalent circuit diagram of the embodiment. 5 is a perspective view showing a conventional example, FIG. 6 is a view showing an example of use of the same device, FIG. 7 is a partial sectional view of the same conventional example, and FIG.
The figure is an equivalent circuit diagram, and FIG. 9 is a frequency characteristic diagram. 3... Housing case, 3a Front plate, 3b
・・Front air chamber, 3C・Back air chamber, 4・・Microphone, 4a
, 4b...Sound hole, 4C...Microphone output end, M
a... Air mass, Sa... Air stiffness. Name of agent: Patent attorney Toshio Nakao (1st person)
Figure 2 Figure 3 Figure 4 Figure 6 Figure 7 Figure 8 Figure 9 Figure 1! ] Kasa number

Claims (2)

[Claims] (1) An exhalation flow sensor characterized in that a front air chamber is provided in the front part of the microphone, and a plurality of sound holes for ventilating the air chamber are arranged on a curved front plate in front of the air chamber. (2) The expiratory flow sensor according to claim 1, characterized in that a differential microphone is used and a back air chamber is provided at the back of the microphone.