US 12,666,206 B2Granted

Acoustic feature computing apparatus, acoustic feature computing method, and program

AssigneeNTT, Inc.

InventorsKenji Ishikawa, Yoshifumi Shiraki, Takehiro Moriya

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Abstract

A technique for accurately measuring acoustic characteristics of a parametric array is provided. A first calculation unit that calculates a complex amplitude d of an optical phase at a frequency fd from an amount of change φs of the optical phase caused by demodulated sound S, assuming that qdiff(ξ′, η′) is a function defined using a Gaussian beam expansion method, a second calculation unit that calculates a function value qdiff(ξ, η) at a point X and a line integral value ∫Lqdiff(ξ′, η)dξ′ of the function qdiff(ξ′, η) along the optical path L, and a third calculation unit that calculates a complex amplitude p of the demodulated sound with the frequency fd at the point X using the complex amplitude d, the function value qdiff(ξ, η), and the line integral value ∫Lqdiff(ξ′, η)dξ′ are included.

Claims4

Dependent claims

An acoustic characteristics measurement device comprising

a transducer configured to generate a parametric array to generate demodulated sound S as audible sound in a sound field, the transducer being a substantially circular sound source;
a phase change measurement device configured to measure a phase change of light due to the demodulated sound S;
a light source device configured to emit the light along an optical path toward the phase change measurement device through the sound field;
and
a processor configured to execute operations comprising:
where L represents the optical path for the phase change measurement device,
C represents a point at which the optical path L intersects a straight line passing through the transducer and parallel to a propagation direction of the demodulated sound S,
X represents a point on the optical path L at which a distance from the point C is x,
z represents a distance from the transducer to the optical path L,
a represents a radius of the transducer, fd=|f1−f2| (where f1 is a frequency of a carrier wave and f2 is a frequency of a sideband wave) represents a frequency of the demodulated sound S, and
c represents a speed of sound,
calculating a complex amplitude d of an optical phase at the frequency fd from an amount of change φs of the optical phase caused by the demodulated sound S;
where a function qdiff(ξ′, η′) represents a predetermined function using a Gaussian beam expansion method,
calculating a function value of the function qdiff(ξ, η) at the point X (where ξ=x/a, η=2z/ka2, k1=f1/c, k2=f2/c, and k=(k1+k2)/2 are satisfied) and a line integral value ∫Lqdiff(ξ′, η)dξ′ of the function qdiff(ξ′, η) along the optical path L;
and
calculating a complex amplitude p of the demodulated sound with the frequency fd at the point X using the complex amplitude d of the optical phase at the frequency fd, the function value qdiff(ξ, η) at the point X, and the line integral value ∫Lqdiff(ξ′, η)dξ′ of the function qdiff(ξ′, η) along the optical path L, and the complex amplitude p of the demodulated sound represents an acoustic characteristic of the parametric array with accuracy.

13 more elements

An acoustic characteristics measurement method comprising:

generating a parametric array, by a transducer, to generate demodulated sound S as audible sound in a sound field, the transducer being a substantially circular sound source;
measuring, by a phase change measurement device, a phase change of light due to the demodulated sound S;
emitting, by a light source device, the light along an optical path toward the phase change measurement device through the sound field;
where L represents the optical path for the phase change measurement device,
C represents a point at which the optical path L intersects a straight line passing through the transducer and parallel to a propagation direction of the demodulated sound S,
X represents a point on the optical path L at which a distance from the point C is x,
z represents a distance from the transducer to the optical path L,
a represents a radius of the transducer, fd=|f1−f2| (where f1 is a frequency of a carrier wave and f2 is a frequency of a sideband wave) represents a frequency of the demodulated sound S, and
c represents the speed of sound,
calculating a complex amplitude d of an optical phase at the frequency fd from an amount of change φs of the optical phase caused by the demodulated sound S;
where a function qdiff(ξ′, η′) represents a predetermined function using a Gaussian beam expansion method,
calculating a function value of the function qdiff(ξ, η) at the point X (where ξ=x/a, η=2z/ka2, k1=f/c, k2=f2/c, and k=(k1+k2)/2 are satisfied) and a line integral value ∫Lqdiff(ξ′, η)dξ′ of the function qdiff(ξ′, η) along the optical path L;
and
calculating a complex amplitude p of the demodulated sound with the frequency fd at the point X using the complex amplitude d of the optical phase at the frequency fd, the function value qdiff(ξ, η) at the point X, and the line integral value ∫Lqdiff(ξ′, η)dξ′ of the function qdiff(ξ′, η) along the optical path L, and the complex amplitude p of the demodulated sound represents an acoustic characteristic of the parametric array with accuracy.

11 more elements

Dependencies are inferred from the claim text.