Abstract: A method includes: generating a first and second shift signal by using a phase of a sound signal regarding an M-channel or a S-channel, the sound signal of the M-channel and the sound signal of the S-channel being obtained by using a mid-side microphone, the sound signal of the S-channel including a positive channel and a negative channel, the first shift signal being configured to reduce a phase difference caused by a difference between a sound arrival distance to the M-channel and a sound arrival distance to the positive channel of the S-channel, the second shift signal being configured to reduce a phase difference caused by a difference between the sound arrival distance to the M-channel and a sound arrival distance to the negative channel of the S-channel; and approximately converting the first or second shift signal into an L-channel signal and an R-channel signal of an XY-microphone.

Abstract: A method for encoded-sound determination performed by a computer includes: executing a first process that includes obtaining information indicating intensities of sound signals, the frequencies being calculated from the sound signals and corresponding to frequencies; and executing a second process that includes determining whether or not the sound signals are signals of encoded sound, based on whether or not the intensities of the sound signals in predetermined frequency bands that are adjacent to each other in a frequency direction have a difference that is larger than or equal to a predetermined threshold.

Abstract: A method includes: generating a first and second shift signal by using a phase of a sound signal regarding an M-channel or a S-channel, the sound signal of the M-channel and the sound signal of the S-channel being obtained by using a mid-side microphone, the sound signal of the S-channel including a positive channel and a negative channel, the first shift signal being configured to reduce a phase difference caused by a difference between a sound arrival distance to the M-channel and a sound arrival distance to the positive channel of the S-channel, the second shift signal being configured to reduce a phase difference caused by a difference between the sound arrival distance to the M-channel and a sound arrival distance to the negative channel of the S-channel; and approximately converting the first or second shift signal into an L-channel signal and an R-channel signal of an XY-microphone.

Abstract: There is provided an audio encoding apparatus including a memory, and a processor coupled to the memory and the processor configured to determine whether a tone is included in a boundary between a low-frequency that is a frequency bandwidth below a predetermined frequency of an input signal and a high-frequency that is a frequency bandwidth above the predetermined frequency of the input signal, suppress a tone in one of the low-frequency and the high-frequency, encode the input signal having the low-frequency to generate a low-frequency code, encode the input signal having the high-frequency to generate a high-frequency code, and generate an encoded stream by multiplexing the low-frequency code and the high-frequency code.

Abstract: A speaker direction determination method includes acquiring a physical quantity indicating at least one of a phase difference and a sound pressure difference based on a plurality of sound signals acquired by the plurality of microphones; generating a correction model corrected such that the physical quantity in a correspondence in a reference model indicating the correspondence between a sound incidence angle onto the plurality of microphones in the case where the housing is located at the reference position and the physical quantity acquired in the case where the housing is located at the reference position corresponds to noise level indicated by the acquired noise information; setting the physical quantity corresponding to the sound incidence angle associated with the inclination indicated by the acquired inclination information in the correction model as a threshold; comparing the acquired physical quantity with the set threshold to determine a speaker direction.

Abstract: A noise suppression method performed by a computer includes: obtaining input sound; detecting a cycle of power change in a non-voice segment included in the input sound; calculating a correction amount that periodically changes and is applied to a voice segment included in the input sound based on the cycle; and correcting power in at least the voice segment based on the correction amount.

Abstract: A non-transitory computer-readable recording medium stores therein a program for causing a computer to execute processing including: converting a speech recognition result of speech recognition performed on an input voice for each of a plurality of languages into a phoneme string; calculating a phoneme count for each of the plurality of languages from the corresponding one of the phoneme strings obtained by the conversion for the respective languages; and identifying a type of language matched with the input voice based on the phoneme counts calculated for the respective languages.

Abstract: A pitch extraction device includes a processor configured to perform a process including: dividing a first bit stream in encoded data into a plurality of sections each having a prescribed section length, the encoded data being obtained by performing entropy encoding on a residual signal calculated by performing linear prediction analysis on a sound signal; allocating a first value or a second value to each of the plurality of sections in the first bit stream in accordance with a bit value in each of the plurality of sections; generating a second bit stream obtained by re-encoding the first bit stream according to the first value and the second value that have been allocated to each of the plurality of sections in the first bit stream; and calculating a fundamental frequency of the sound signal in accordance with an autocorrelation of the second bit stream.

Abstract: A method for encoded-sound determination performed by a computer includes: executing a first process that includes obtaining information indicating intensities of sound signals, the frequencies being calculated from the sound signals and corresponding to frequencies; and executing a second process that includes determining whether or not the sound signals are signals of encoded sound, based on whether or not the intensities of the sound signals in predetermined frequency bands that are adjacent to each other in a frequency direction have a difference that is larger than or equal to a predetermined threshold.

Abstract: An abnormality detecting device includes a memory, and a processor coupled to the memory and configured to: detect an envelope of an audio signal indicating a periodic sound emitted by a target object and a periodic sound emitted by another object; execute time-to-frequency conversion on the envelope to calculate a frequency spectrum of the audio signal; and determine whether or not the target object has an abnormality, based on a frequency component included in the frequency spectrum and corresponding to a time interval between time points when the sound is emitted by the target object.

Abstract: An abnormality detecting device includes a processor coupled to a memory and configured to: detect an envelope of a sound signal representing a periodic sound emitted from the rotor including a predetermined number of blades and a periodic sound emitted from another object; perform a time frequency transform of the envelope for each of frames having a predetermined time length and calculate a frequency spectrum of the sound signal; detect a candidate of a frequency equivalent to a period of the sound emitted from the rotor; and obtain a duration in which a fluctuation in power with respect to power of a component of the frequency spectrum in the candidate detected with regard to the frame becomes lower than or equal to a certain level and identify the candidate in which the duration becomes longest as the frequency equivalent to the period of the sound emitted from the rotor.

Abstract: An abnormality detecting device includes a memory, and a processor coupled to the memory and configured to: detect an envelope of an audio signal indicating a periodic sound emitted by a target object and a periodic sound emitted by another object; execute time-to-frequency conversion on the envelope to calculate a frequency spectrum of the audio signal; and determine whether or not the target object has an abnormality, based on a frequency component included in the frequency spectrum and corresponding to a time interval between time points when the sound is emitted by the target object.

Abstract: An audio coding device includes a filter configured to extract a low-band signal having a first frequency component from an input signal, a memory, and a processor coupled to the memory and configured to extract envelope information relating to an envelope of a high-band signal having a second frequency component which is higher than the first frequency component in the input signal, detect tone information that is information on a tone signal included in a high-band signal spectrum from the input signal, correct the envelope information based on a difference between frequency of the tone signal and frequency of a peak of the envelope, and code the low-band signal, the tone information, and the envelope information that is corrected.

Abstract: There is provided an audio encoding apparatus including a memory, and a processor coupled to the memory and the processor configured to determine whether a tone is included in a boundary between a low-frequency that is a frequency bandwidth below a predetermined frequency of an input signal and a high-frequency that is a frequency bandwidth above the predetermined frequency of the input signal, suppress a tone in one of the low-frequency and the high-frequency, encode the input signal having the low-frequency to generate a low-frequency code, encode the input signal having the high-frequency to generate a high-frequency code, and generate an encoded stream by multiplexing the low-frequency code and the high-frequency code.

Abstract: An audio coding device includes a filter configured to extract a low-band signal having a first frequency component from an input signal, a memory, and a processor coupled to the memory and configured to extract envelope information relating to an envelope of a high-band signal having a second frequency component which is higher than the first frequency component in the input signal, detect tone information that is information on a tone signal included in a high-band signal spectrum from the input signal, correct the envelope information based on a difference between frequency of the tone signal and frequency of a peak of the envelope, and code the low-band signal, the tone information, and the envelope information that is corrected.

Abstract: A pitch extraction device includes a processor configured to perform a process including: dividing a first bit stream in encoded data into a plurality of sections each having a prescribed section length, the encoded data being obtained by performing entropy encoding on a residual signal calculated by performing linear prediction analysis on a sound signal; allocating a first value or a second value to each of the plurality of sections in the first bit stream in accordance with a bit value in each of the plurality of sections; generating a second bit stream obtained by re-encoding the first bit stream according to the first value and the second value that have been allocated to each of the plurality of sections in the first bit stream; and calculating a fundamental frequency of the sound signal in accordance with an autocorrelation of the second bit stream.

Abstract: An audio encoding device includes a processor; and a memory which stores a plurality of instructions, which when executed by the processor, cause the processor to execute: calculating a similarity in phase of a first channel signal and a second channel signal contained in a plurality of channels of an audio signal; and selecting, based on the similarity, a first output that outputs one of the first channel signal and the second channel signal, or a second output that outputs both of the first channel signal and the second channel signal.

Abstract: A plurality of candidates of prediction coefficients of a channel signal out of a plurality of channel signals are extracted from a code book storing a plurality of prediction coefficients, each candidate having a predictive error falling within a specific range of predictive error of predictive encoding of two other channel signals, and a prediction coefficient is selected from the extracted candidates as a result of the predictive encoding in accordance with a specific data embedding rule and embedding embed target data into the selected prediction coefficient.

Abstract: A device for embedding data upon a prediction coding of a multi-channel signal includes a storage unit to store a code book that includes a plurality of prediction parameter sets, each of the plurality of prediction parameter sets including a plurality of kinds of prediction parameters for a processing regarding the prediction coding. The device extracts a plurality of candidates of a prediction parameter set for the multi-channel signal from the code book, wherein the plurality of candidates are capable of suppressing a prediction error in the prediction coding within a predetermined range, converts an embedding object that is at least part of the data in accordance with a number corresponding to a number of the candidates, selects, from the plurality of candidates, the prediction parameter set corresponding to the converted embedding object, and multiplexes the selected prediction parameter set with coded data which are down-mixed from the multi-channel signal.

Abstract: An orthogonal transform apparatus includes: an interchanging unit which interchanges MDCT coefficients contained in a first half of a prescribed interval with MDCT coefficients contained in a second half thereof; an inverting unit which inverts the sign of the MDCT coefficients contained in the second half of the prescribed interval after the interchange; an inverse cosine transform unit which computes the real components of QMF coefficients by applying an IMDCT using FFT to the MDCT coefficients contained in the first half and the sign-inverted MDCT coefficients contained in the second half; an inverse sine transform unit which computes the imaginary components of the QMF coefficients by applying an IMDST using FFT to the MDCT coefficients contained in the first half and the sign-inverted MDCT coefficients contained in the second half; and a coefficient adjusting unit which computes the QMF coefficients by combining the real components with the imaginary components.