Abstract: The above sound reproduction device is applied to an acoustic space such as a passenger compartment, and controls the levels of the reproduced sounds at two evaluation points set at the seats in the passenger compartment, for example. Specifically, the sound reproduction device controls the phase of the sound signal inputted from external and supplies the sound signals to the pair of speakers. The phase control is performed for each of the plurality of listening positions such that a sum of reproduced sound levels at the two evaluation points becomes larger than the sum obtained in a case where the sound signal is reproduced only one of the pair of speakers.

Abstract: A surround signal generating device includes: a surround signal generating unit which subtracts a sound signal obtained by multiplying a first gain by an inputted sound signal of a right channel from an inputted sound signal of a left channel so as to generate a surround signal of the left channel, and which subtracts a sound signal obtained by multiplying a second gain by the inputted sound signal of the left channel from the inputted sound signal of the right channel so as to generate a surround signal of the right channel; and a gain setting unit which sets the first gain and the second gain so that a correlation between the surround signal of the left channel and the surround signal of the right channel which are generated by the surround signal generating unit realizes a correlation between surround signals of an actual content having a surround sound.

Abstract: The disclosed active vibration noise control device is suitable for use in cancelling out vibration noise by outputting control noise from a plurality of speakers. When a vibration noise frequency is in a dip bandwidth, the active vibration noise control device alters the step size parameters used to update the filter coefficient at at least one filter coefficient update means from among a plurality of filter coefficient update means. Thus, the filter coefficient update speed can be retarded in unstable dip bandwidths, enabling loss in silencing effect which occurs during dip characteristics to be appropriately reduced.

Abstract: The above sound reproduction device is applied to an acoustic space such as a passenger compartment, and controls the levels of the reproduced sounds at two evaluation points set at the seats in the passenger compartment, for example. Specifically, the sound reproduction device controls the phase of the sound signal inputted from external and supplies the sound signals to the pair of speakers. The phase control is performed for each of the plurality of listening positions such that a sum of reproduced sound levels at the two evaluation points becomes larger than the sum obtained in a case where the sound signal is reproduced only one of the pair of speakers.

Abstract: An active vibration noise control device cancels vibration noise by making plural speakers generate control sounds. The active vibration noise control device selects one or more speakers which output the control sounds, from plural speakers, based on a relationship between (1) a first phase difference which corresponds to a difference between phase characteristics of the vibration noise from a vibration noise source to an evaluation point and phase characteristics of the vibration noise from the vibration noise source to a pseudo evaluation point and (2) a second phase difference for each of the plural speakers corresponding to a difference between phase characteristics of the control sound from the speaker to the evaluation point and phase characteristics of the control sound from the speaker to the pseudo evaluation point. Therefore, it stably decreases the vibration noise at the pseudo evaluation point independently of a frequency band of the vibration noise.

Abstract: An active vibration noise control device having a pair of speakers, including: a basic signal generating unit generating a basic signal based on a vibration noise frequency; an adaptive notch filter generating a first control signal provided to one speaker using a first filter coefficient and generating a second control signal provided to the other speaker using a second filter coefficient to cancel the generated vibration noise; a microphone detecting cancellation error between the vibration noise and the control sounds and outputting an error signal; a reference signal generating unit generating a reference signal based on a transfer function from the speakers to the microphone; a filter coefficient updating unit updating first and second filter coefficients, minimize the error signal; and a phase difference limiting unit limiting a phase difference between control sounds generated by different speakers. Therefore, it becomes possible to appropriately ensure a uniform and wide noise-cancelled area.

Abstract: A surround signal generating device includes: a surround signal generating unit which subtracts a sound signal obtained by multiplying a first gain by an inputted sound signal of a right channel from an inputted sound signal of a left channel so as to generate a surround signal of the left channel, and which subtracts a sound signal obtained by multiplying a second gain by the inputted sound signal of the left channel from the inputted sound signal of the right channel so as to generate a surround signal of the right channel; and a gain setting unit which sets the first gain and the second gain so that a correlation between the surround signal of the left channel and the surround signal of the right channel which are generated by the surround signal generating unit realizes a correlation between surround signals of an actual content having a surround sound.

Abstract: The disclosed active vibration noise control device is suitable for use in cancelling out vibration noise by outputting control noise from a plurality of speakers. When a vibration noise frequency is in a dip bandwidth, the active vibration noise control device alters the step size parameters used to update the filter coefficient at at least one filter coefficient update means from among a plurality of filter coefficient update means. Thus, the filter coefficient update speed can be retarded in unstable dip bandwidths, enabling loss in silencing effect which occurs during dip characteristics to be appropriately reduced.

Abstract: An active vibration noise control device cancels vibration noise by making plural speakers generate control sounds. The active vibration noise control device selects one or more speakers which output the control sounds, from plural speakers, based on a relationship between (1) a first phase difference which corresponds to a difference between phase characteristics of the vibration noise from a vibration noise source to an evaluation point and phase characteristics of the vibration noise from the vibration noise source to a pseudo evaluation point and (2) a second phase difference for each of the plural speakers corresponding to a difference between phase characteristics of the control sound from the speaker to the evaluation point and phase characteristics of the control sound from the speaker to the pseudo evaluation point. Therefore, it stably decreases the vibration noise at the pseudo evaluation point independently of a frequency band of the vibration noise.

Abstract: An active vibration noise control device having a pair of speakers, including: a basic signal generating unit generating a basic signal based on a vibration noise frequency; an adaptive notch filter generating a first control signal provided to one speaker using a first filter coefficient and generating a second control signal provided to the other speaker using a second filter coefficient to cancel the generated vibration noise; a microphone detecting cancellation error between the vibration noise and the control sounds and outputting an error signal; a reference signal generating unit generating a reference signal based on a transfer function from the speakers to the microphone; a filter coefficient updating unit updating first and second filter coefficients, minimize the error signal; and a phase difference limiting unit limiting a phase difference between control sounds generated by different speakers. Therefore, it becomes possible to appropriately ensure a uniform and wide noise-cancelled area.

Abstract: At least two speakers are arranged in the left-right direction, and the measurement signal generating unit generates the measurement signal from the two speakers. The measurement signal outputting unit outputs the measurement signal. The measurement signal collecting unit collects the measurement signal for the left-right direction from at least two positions along the left-right direction axis in the acoustic space. The delay correcting unit performs the delay adjustment for any one of the speakers in the acoustic space, based on information that the measurement signal collecting unit obtains by collecting the measurement signal for the left-right direction, until the level difference in the left-right direction becomes equal to or smaller than the predetermined value. The sound field correcting device collects the measurement signal from two positions along the left-right direction axis, and reduces the level difference in the left-right direction based on the information obtained by collecting the sound.

Abstract: A speaker characteristic correction device obtains a first speaker information of a first speaker, obtains a first sound field characteristic at an evaluation point that is obtained by using the first speaker in advance, and obtains a second speaker parameter indicating a mechanical characteristic and an electric characteristic of a second speaker. Then, the speaker characteristic correction device calculates a correction characteristic based on the first speaker information and the second speaker parameter, and calculates the second sound field characteristic by applying the correction characteristic to the first sound field characteristic. Thereby, when the speaker type is changed, it is possible to easily calculate the sound field characteristic without performing the re-measurement by installing the speaker and without performing the re-analysis by setting the analysis condition.