# US 2014/0192993 A1 · Reverberation suppression device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0192993 A1 - Document ID: US20140192993A1 - Status: Published application - Kind: A1 - Application number: 14/238,478 - Filed: 2012-01-30 - Published: 2014-07-10 - Earliest claimed: 2012-01-30 - Assignees: Mitsubishi Electric Corporation - Inventors: Takashi Mikami; Atsuyoshi Yano - Web page: https://patentgrep.com/patent/US20140192993A1 ## CPC - G10K 11/002: {Devices for damping, suppressing, obstructing or conducting sound in acoustic devices (G10K1/06 - G10K1/10 take precedence; for electro-mechanical transducers for communication H04R3/002)} - H04M 9/082: {using echo cancellers (echo cancellers per se H04B3/23)} - H04R 3/02: for preventing acoustic reaction {, i.e. acoustic oscillatory feedback (specially adapted for hearing aids H04R25/453)} - G10L 2021/02082: {the noise being echo, reverberation of the speech} - H04R 2499/13: Acoustic transducers and sound field adaptation in vehicles - H04S 7/00: Indicating arrangements; Control arrangements, e.g. balance control - H04S 2420/05: Application of the precedence or Haas effect, i.e. the effect of first wavefront, in order to improve sound-source localisation - G10K: SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR - H04M: TELEPHONIC COMMUNICATION (circuits for controlling other apparatus via a telephone cable and not involving telephone switching apparatus G08) - 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) - G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING - H04S: STEREOPHONIC SYSTEMS ## Abstract A reverberation suppression device comprises: an echo canceller that removes an echo component included in an input signal; a howling suppressor that detects occurrence of howling based on a frequency characteristic of the input signal from which the echo component has been removed and attenuates a frequency level of a component of the detected howling; and an initial sound suppressor that detects a sound section of the input signal in which the frequency level of the howling component has been attenuated and suppresses a signal value at a sound start portion of the detected sound section. ## Claims ### Claim 1 A reverberation suppression device comprising: an initial sound suppressor that detects a sound section of an input signal and suppresses a signal value at a sound start portion of the detected sound section. ### Claim 2 (depends on 1) The reverberation suppression device according to claim 1, wherein the initial sound suppressor comprises: a filter that converts a signal value of the input signal on a basis of a filter coefficient; a short-time power moving average calculator that refers to the input signal, and calculates short-time power by taking a moving average of power of signal values for a predetermined time period to smooth said power of signal values; a filter coefficient setting unit that sets a parameter of the filter coefficient on a basis of a characteristic of the input signal; a filter coefficient calculator that calculates the filter coefficient by using the short-time power calculated by the short-time power moving average calculator and the parameter of the filter coefficient set by the filter coefficient setting unit; and a coefficient limiter that sets an upper limit value of the filter coefficient for the filter, wherein the filter converts the signal value of the input signal on a basis of the filter coefficient calculated by the filter coefficient calculator or the upper limit value of the filter coefficient set by the coefficient limiter. ### Claim 3 (depends on 2) The reverberation suppression device according to claim 2, further comprising a long-time power moving average calculator that refers to the input signal, and calculates long-time power by taking a moving average of power of signal values for a time period to smooth said power of signal values, the time period being longer than the time period used by the short-time power moving average calculator, wherein the filter coefficient setting unit sets the parameter on a basis of the long-time power calculated by the long-time power moving average calculator. ### Claim 4 (depends on 2) The reverberation suppression device according to claim 2, further comprising an signal variation calculator that calculates variation of the signal value of the input signal, and detects variations of signal values at the sound start portion and a sound end portion of the sound section by using a hysteresis characteristic which depends on the calculated variations, wherein the filter coefficient calculation unit calculates the filter coefficient by using the variations of signal value at the sound start portion and the sound end portion of the sound section detected by the signal variation calculator, the short-time power calculated by the short-time power moving average calculator, and the parameter of the filter coefficient set by the filter coefficient setting unit. ### Claim 5 (depends on 3) The reverberation suppression device according to claim 3, further comprising an signal variation calculator that calculates variation of the signal value of the input signal, and detects variations of signal values at the sound start portion and a sound end portion of the sound section by using a hysteresis characteristic which depends on the calculated variations, wherein the filter coefficient calculation unit calculates the filter coefficient by using the variations of signal value at the sound start portion and the sound end portion of the sound section detected by the signal variation calculator, the short-time power calculated by the short-time power moving average calculator, and the parameter of the filter coefficient set by the filter coefficient setting unit.