Acoustic metamaterial device, method and computer program

A device for room geometry analysis comprising:

• a plurality of segments built of acoustic metamaterials, each segment acting as a waveguide with a unique transfer function;
• and
• a processor configured to:
• calculate delays and respective directions of mirror sound sources by decomposing a sound signal obtained from a microphone based on the transfer functions of the segments and based on a calibration signal emitted by a speaker;
• and
• determine a normal vector of a wall and a wall point based on locations of the mirror sound sources and a location of the speaker.

A device for room geometry analysis comprising:

• a plurality of segments built of acoustic metamaterials, each segment acting as a waveguide with a unique transfer function;
• and
• a processor configured to:
• calculate delays and respective directions of mirror sound sources by decomposing a sound signal obtained from a microphone based on the transfer functions of the segments and based on a calibration signal emitted by a speaker;
• and
• decompose the sound signal (Ŝ) based on the formula
• S
• ^
• =
• ∑
• φ
• ,
• θ
• ⁢
• c
• ⁡
• (
• φ
• ,
• θ
• )
• ⁢
• (
• tsp
• ⁡
• (
• t
• -
• τ
• ⁡
• (
• φ
• ,
• θ
• )
• )
• *
• b
• ⁡
• (
• φ
• ,
• θ
• ,
• t
• )
• )
• wherein c(φ, θ) are angle-dependent amplitude coefficients that represent the attenuation function of the room wall reflections, tsp(t) is the calibration signal, τ(φ, θ) is the delay, b(φ, θ, t) is the transfer function in time-domain, * is a convolution operation and (φ, θ) are polar and azimuthal coordinates refering to the segments. The sum Σφ,θ is performed over all segments with coordinates (φ, θ).

A method comprising:

• emitting a calibration signal;
• obtaining a sound signal;
• calculating delays and respective directions of mirror sound sources by decomposing the sound signal based on the transfer functions of a plurality of segments and based on the calibration signal, the segments built of acoustic metamaterials, each segment acting as a waveguide with a unique transfer function,
• wherein the mirror sound sources are mirror images of the calibration signal.

A non-transitory computer readable medium comprising instructions, which when executed on a processor:

• emit a calibration signal;
• obtain a sound signal;
• calculate delays and respective directions of mirror sound sources by decomposing the sound signal based on the transfer functions of a plurality of segments and based on the calibration signal, the segments built of acoustic metamaterials, each segment acting as a waveguide with a unique transfer function,
• wherein the mirror sound sources are mirror images of the calibration signal.