# US 10,764,703 B2 · Acoustic metamaterial device, method and computer program > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,764,703 B2 - Document ID: US10764703B2 - Status: Granted - Kind: B2 - Application number: 16/362,692 - Filed: 2019-03-25 - Published: 2019-10-03 - Granted: 2020-09-01 - Earliest claimed: 2018-03-28 - Assignees: Sony Corporation - Applicants: Sony Corporation - Inventors: Franck Giron; Fabien Cardinaux; Thomas Kemp; Stefan Uhlich; Marc Ferras Font; Andreas Schwager; Patrick Putzolu - Web page: https://patentgrep.com/patent/US10764703B2 ## CPC - G01S 15/003: {Bistatic sonar systems; Multistatic sonar systems} - H04S 7/301: {Automatic calibration of stereophonic sound system, e.g. with test microphone} - G01S 7/521: Constructional features - G01S 7/527: Extracting wanted echo signals {(Doppler systems G01S15/50)} - G01S 7/539: using analysis of echo signal for target characterisation; Target signature; Target cross-section - G01S 15/42: Simultaneous measurement of distance and other co-ordinates (indirect measurement G01S15/46) - G01S 15/89: for mapping or imaging - G06F 17/11: for solving equations {, e.g. nonlinear equations, general mathematical optimization problems (optimization specially adapted for a specific administrative, business or logistic context G06Q10/04)} - H04R 1/342: {for microphones} - H04R 3/04: for correcting frequency response - H04S 7/305: {Electronic adaptation of stereophonic audio signals to reverberation of the listening space (H04S7/301 takes precedence)} - H04S 2420/01: Enhancing the perception of the sound image or of the spatial distribution using head related transfer functions [HRTF's] or equivalents thereof, e.g. interaural time difference [ITD] or interaural level difference [ILD] - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES - H04S: STEREOPHONIC SYSTEMS - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K) ## Abstract A device for room geometry analysis comprising: a plurality of segments (101-106) built of acoustic metamaterials, each segment (φ, θ) acting as a waveguide with a unique transfer function (B(φ, θ, ω)); and a processor configured to calculate delays (τ(φ, θ)) and respective directions (c(φ, θ)) of mirror sound sources (721-725) by decomposing a sound signal (Ŝ) obtained from a microphone (110) based on the transfer functions (B(φ, θ, ω)) of the segments (101-106) and based on a calibration signal (tsp(t)) emitted by a speaker (420). ## Claims ### Claim 1 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, wherein the mirror sound sources are mirror images of the calibration signal. ### Claim 2 (depends on 1) The device of claim 1, wherein the processor is configured to determine, for each delay and the respective direction, a location of a respective mirror sound source, of the mirror sound sources based on the delay and the respective direction. ### Claim 3 (depends on 1) The device of claim 1, wherein the processor is configured to determine the directions from angle-dependent amplitude coefficients of the sound signal. ### Claim 4 (depends on 1) The device of claim 1, in which the calibration signal has a flat spectral density. ### Claim 5 (depends on 1) The device of claim 1, in which the calibration signal is a time-stretch pulse signal. ### Claim 6 (depends on 1) The device of claim 1, wherein the processor is configured to decompose the sound signal based on compressive sensing techniques. ### Claim 7 (depends on 1) The device of claim 1, wherein the processor is configured to decompose the sound signal based on the minimization of the L1 norm of the sound signal. ### Claim 8 (depends on 1) The device of claim 1, wherein the processor is configured to decompose the sound signal based on additional constraints. ### Claim 9 (depends on 1) The device of claim 1, in which at least one of the segments is a Helmholtz resonator. ### Claim 10 (depends on 1) The device of claim 1, in which the segments are arranged around the microphone in a cylindrical, spherical, circular, cubic, cuboid or planar shape. ### Claim 11 (depends on 1) The device of claim 1, wherein the processor is further configured to estimate a room geometry using the decomposed sound signal. ### Claim 12 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. ### Claim 13 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). ### Claim 14 (depends on 13) The device of claim 13, wherein the processor is configured to optimize the following error function: I = ( S - S ^ ) 2 + β ⁢ ∑ φ , θ ⁢  c ⁡ ( φ , θ )  wherein I is the error function that is minimized, S is the numerical function that is fitted, c(φ, θ) are angle-dependent amplitude coefficients β is a predefined coefficient that influences the order of the decomposition, Σφ,θ∥c(φ,θ)∥ is the sum of the L1 norms of the c coefficients over all segments (φ, θ). ### Claim 15 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. ### Claim 16 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.