JPS6322498Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a microphone adapter that provides a predetermined narrow directional characteristic to a microphone having a wide directional characteristic. In particular, the present invention relates to a microphone adapter suitable for measuring a sound source coming from a specific direction in a simple anechoic chamber.

[Description of prior art]

In simple anechoic chambers used to measure engine noise, the sound absorption of floors, barriers, etc. is not necessarily sufficient, and furthermore, auxiliary machinery is scattered throughout the room, and noise is generated from these auxiliary machinery. Therefore, even if an attempt is made to measure a desired engine noise level, it is difficult to accurately measure the engine noise level because the reflected sound and noise generated from auxiliary machinery are mixed in. For example, if you compare the noise level measured in a large engine anechoic chamber that almost completely absorbs reflected sound with the noise level measured in a simple anechoic chamber, the noise level in the simple anechoic chamber appears to be approximately 1.5 dB higher. In order to solve this problem, increasing the size of the anechoic chamber had disadvantages such as requiring a vast site area and expensive equipment investment.

[Purpose of invention]

This invention can accurately measure the noise level of a noise source with a predetermined narrow directional pattern using a microphone with a wide directional pattern in a simple anechoic chamber, and prevents unnecessary reflected sound and other noise from being mixed in. The purpose is to provide a microphone adapter that can.

[Characteristics of the invention]

The present invention includes an outer plate formed in the shape of a rotating radial surface,
A large number of conical inner plates are installed in a stacked manner with their tops oriented in the radial direction inside this rotating radial surface, and the tops are cut parallel to the bottom surface and the cut ends are formed approximately parallel to the radial surface. A sound-absorbing material filled between the plate and the inner plate, and a microphone mounting part to which an omnidirectional microphone can be detachably mounted at the center of the rotating radiation surface in the axial direction of the radiation surface. It is characterized by

[Explanation based on examples]

An explanation will be given below based on the drawings of the embodiment.

FIG. 1 is a longitudinal sectional view of an adapter according to an embodiment of the present invention.
FIG. 2 is a plan view thereof. In FIGS. 1 and 2, reference numeral 1 denotes a thin iron outer plate forming a paraboloid of revolution. On the inside of this outer plate 1, the top is directed in the axial direction of this paraboloid, that is, in the direction of the arrow in FIG.
Moreover, a large number (six in this example) of conical iron inner plates 2 whose tops are cut parallel to the bottom are stacked and attached in a laminated manner. Each of the conical cut ends of the plurality of inner plates 2 is formed substantially parallel to the paraboloid of the outer plate 1. In addition, the inclination angle α that the cone of the inner plate 2 forms with its bottom surface and the opening angle θ formed by each of the above-mentioned cut holes are as follows:
It is set depending on the size of the engine whose noise level is to be measured and the measurement distance between the engine and the adapter.

Further, a sound absorbing material 3 made of open-cell foamed urethane is filled between the inner plates 2. Further, a microphone mounting portion 4 is provided at the center of the paraboloid of rotation of the outer plate 1 in the axial direction of the paraboloid. The microphone mounting portion 4 is removably mounted with an outer cylinder of a microphone A having a wide directional characteristic.

A method of measuring the engine noise level in a simple anechoic chamber by attaching the microphone A to the adapter having such a configuration will be described. First, when the adapter with microphone A attached is pointed toward the engine, the aperture angle θ includes the radiation angle of the engine sound to be measured, and other noises and reflected sounds other than the engine sound are reflected from the outer panel 1. Otherwise, the noise is absorbed by the sound-absorbing material 3 filled between the inner plates 2 and is no longer mixed into the microphone A, making it possible to measure the engine noise level as accurately as in a large anechoic chamber.

Although the above example shows an example in which the outer plate 1 is formed into a paraboloid of revolution, it is not limited to a paraboloid of revolution, but may be formed into another radial shape of revolution, such as a conical shape.

Furthermore, although an example has been shown in which the iron inner plate is attached in a laminated manner within the iron outer plate of the adapter, the outer plate and the laminated inner plate may be integrally molded from synthetic resin.

[Effect of idea]

As described above, according to the present invention, a large number of conical disks with cut-off tops are laminated inside a rotating radial outer plate, and a sound absorbing material is filled between the inner plates. By providing a microphone attachment part in the center of this radiation surface that allows you to detachably attach an omnidirectional microphone, even in a simple anechoic chamber where reflected sounds and other noises are generated, reflected sounds generated from directions other than the specified direction can be avoided. It has the excellent effect of nullifying other noises and absorbing only the engine sound in a predetermined direction, making it possible to measure engine noise levels as accurately as in a complete anechoic chamber.

In particular, the wavelength of engine sound is relatively long, so if you configure an adapter with no sound-absorbing material, such as a conventional adapter with only a paraboloid of revolution outer plate, you will have to make a large adapter, but the sound generated from a specific direction will be reduced. According to the present invention, which ignores other factors, there is an advantage that a small adapter can be realized.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an adapter according to an embodiment of the present invention.
Figure 2 is its plan view. 1... Outer plate, 2... Inner plate, 3... Sound absorbing material, 4...
...Microphone attachment part, A...Microphone with wide directional characteristics.

Claims (1)

[Claims for Utility Model Registration] (1) An outer plate formed in the shape of a rotating radial surface having a predetermined radiation angle; a conical inner plate cut parallel to the bottom surface and with its cut end substantially parallel to the radiation surface; a sound absorbing material filled between the inner plates; and the center of the rotating radiation surface. and a microphone mounting portion to which a microphone with a wide directional characteristic can be detachably mounted in the axial direction of the radiation surface. (2) The microphone adapter according to claim 1, wherein the rotating radiation surface is a paraboloid of revolution.