Device for the acquisition and conditioning of an acoustic signal generated by a source of an internal combustion engine
A device for the acquisition and conditioning of a sound signal generated by a source of an internal combustion engine and comprising a box-shaped support body having a first measuring assembly and a second measuring assembly; wherein the first measuring assembly is provided with at least two first microphones which lie on a first plane and are configured for the detection of a first acoustic signal generated by the source along a first provenance direction; and wherein the second measuring assembly is provided with at least a second microphone arranged on a second plane configured for the detection of a second acoustic signal generated by the source along a second provenance direction different from the first provenance direction.
1. A device for the acquisition and conditioning of a sound signal (S) generated by a source of an internal combustion engine comprising: a box-shaped support body having a first measuring assembly and a second measuring assembly; wherein the box-shaped support body is spaced from and does not surround the source; wherein the first measuring assembly is provided with at least two first microphones which lie on a first plane defined by a first wall of the box-shaped support body and detect a first acoustic signal (S X ) generated by the source along a first provenance direction (X); and wherein the second measuring assembly is provided with at least a second microphone arranged on a second plane defined by a second wall of the box-shaped support body and that detects a second acoustic signal (S Y ) generated by the source along a second provenance direction (Y) different from the first provenance direction (X), wherein the measuring assemblies are placed exclusively on the first and on the second walls of the box-shaped support body; wherein the first microphones and/or the second microphones are aligned and spaced by a first distance (D 1 ) and by a second distance (D 2 ), respectively, from one another; wherein the first distance (D 1 ) and the second distance (D 2 ) are a function of the wavelength of the acoustic signal (S) acquired and where:
d
<
λ
2
=
c
2
f
[
2
]
where f is the frequency of the incident wave, c is the speed of sound and λ is the wavelength.
2. The device according to claim 1 , wherein the first plane is orthogonal to the second plane.
3. The device according to claim 1 , wherein the first plane is different from, but parallel to, the second plane.
4. The device according to claim 1 , wherein the first measuring assembly is provided with a plurality of first microphones arranged aligned in rows and columns and equally spaced from one another.
5. The device according to claim 1 , wherein the second measuring assembly is provided with a plurality of second microphones arranged aligned in rows and columns and equally spaced from one another.
6. The device according to claim 1 , wherein the first measuring assembly and the second measuring assembly lie on the same plane.
7. The device according to claim 1 , further including a third measuring assembly provided with at least one microphone which lies on a third plane and is configured for the detection of a third acoustic signal generated by the source along a third provenance direction different from the first and second provenance directions (X, Y).
8. The device according to claim 1 , further including a conditioning circuit for the first acoustic signal (S X ) and the second acoustic signal (S Y ); and an anti-aliasing filter for the first acoustic signal (S X ) and the second acoustic signal (S Y ).