Microphone device
AssigneesDenso Corporation, Toyota Jidosha Kabushiki Kaisha, MIRISE Technologies Corporation
InventorsTakashi Takazawa, Shuhei Shimanoe, Tomoki Tanemura, Masaaki Kawauchi
Life of this patent
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Abstract
A microphone device has plural microphones. A distance between two of the microphones is d. A signal-to-noise ratio of each of the microphones is MicSNR. A speed of sound is c. A frequency to be processed is f. An azimuth angle of an operator's seat relative to the microphones is θ. A minimum azimuth angle to be detected is Δθ. A voltage amplitude of an output signal of the microphone, with reference to a voltage output when a sound of 94 dBA is received, is A. A differential voltage effective ratio EDER is defined by a formula where Δτ=d/c {sin(θ+Δθ)−sin θ}, and the distance d is set to a value that satisfies d<c/2f and EDER>0.7.
Claims14
A microphone device comprising:
- a plurality of microphones, wherein
- a distance d is defined between two of the microphones,
- a signal-to-noise ratio of each of the microphones is defined as MicSNR,
- a speed of sound is defined as c,
- a frequency to be processed is defined as f,
- an azimuth angle of an operator seat with respect to the plurality of microphones is defined as θ,
- a minimum azimuth angle to be detected is defined as Δθ,
- a voltage amplitude of an output signal of the microphone, with reference to an output voltage when receiving a sound of 94 dBA, is defined as A,
- a differential voltage effective ratio EDER is denned as
- EDER
- =
- 2
- π
-
- cos
- -
- 1
-
- 10
- -
- MicSNR
- 20
- 2
-
- A
-
- sin
-
- (
- π
-
- f
-
- Δτ
- )
- where Δτ=d/c{sin(θ+Δθ)−sin θ}, and
- the distance d is set to a value that satisfies d<c/2f and EDER>0.7.
Dependencies are inferred from the claim text.