Abstract: A spherically steerable microphone array structure is provided. The spherically steerable microphone array structure uses pressure and acoustic particle velocity signals obtained from sensors positioned co-planarly on a circular arc. The spherically steerable microphone array structure allows a calculation of all spatial partial derivatives of a sound field up to a given order. The spatial partial derivatives are used to obtain a spherical harmonic decomposition of a recorded sound field. Spherical harmonic decomposition coefficients are used in a spherically direction-invariant acoustic mode beamforming.

Abstract: A method is provided for acoustic source direction of arrival estimation and acoustic source separation, via spatial weighting of the dictionary based display of the steered response function calculated for a certain number of directions from spherical harmonic decomposition coefficients obtained from microphone array recordings of the sound field. The usage of spatial band limited functions of plane waves to represent more complex directional maps of the sound field constitutes the algorithm. These functions are calculated for pre-defined directions on an analysis surface (such as a sphere). The directions of arrival of sound sources are calculated with the same method in order to group source estimates to localize sound sources. Thereby, directions of arrival can be obtained from the recordings of the sound sources captured by means of a microphone array and following this, sound sources can be separated by using this direction information or predetermined source arrival directions.

Abstract: A spherically steerable microphone array structure is provided. The spherically steerable microphone array structure uses pressure and acoustic particle velocity signals obtained from sensors positioned co-planarly on a circular arc. The spherically steerable microphone array structure allows a calculation of all spatial partial derivatives of a sound field up to a given order. The spatial partial derivatives are used to obtain a spherical harmonic decomposition of a recorded sound field. Spherical harmonic decomposition coefficients are used in a spherically direction-invariant acoustic mode beamforming.

Abstract: A method is provided for acoustic source direction of arrival estimation and acoustic source separation, via spatial weighting of the dictionary based display of the steered response function calculated for a certain number of directions from spherical harmonic decomposition coefficients obtained from microphone array recordings of the sound field. The usage of spatial band limited functions of plane waves to represent more complex directional maps of the sound field constitutes the algorithm. These functions are calculated for pre-defined directions on an analysis surface (such as a sphere). The directions of arrival of sound sources are calculated with the same method in order to group source estimates to localize sound sources. Thereby, directions of arrival can be obtained from the recordings of the sound sources captured by means of a microphone array and following this, sound sources can be separated by using this direction information or predetermined source arrival directions.

Abstract: A method of separating a mixture of acoustic signals from a plurality of sources comprises: providing pressure signals indicative of time-varying acoustic pressure in the mixture; defining a series of time windows; and for each time window: a) providing from the pressure signals a series of sample values of measured directional pressure gradient; b) identifying different frequency components of the pressure signals c) for each frequency component defining an associated direction; and d) from the frequency components and their associated directions generating a separated signal for one of the sources.

Abstract: Electronic devices having digital reverberators are disclosed, together with a method of reproducing sound for a user with the digital reverberator. The digital reverberator uses digital surface absorption filters positioned in the reverberator to simulate absorption of energy as digital audio data samples are reflected from virtual surfaces. The position of the digital surface absorption filters enables known frequency-dependent surface absorption characteristics of real materials to be directly implemented using the filter coefficients of each digital surface absorption filter. This enables virtual acoustic spaces to be designed quickly without the need for the digital reverberator to be manually tuned for each space.

Abstract: Electronic devices having digital reverberators are disclosed, together with a method of reproducing sound for a user with the digital reverberator. The digital reverberator uses digital surface absorption filters positioned in the reverberator to simulate absorption of energy as digital audio data samples are reflected from virtual surfaces. The position of the digital surface absorption filters enables known frequency-dependent surface absorption characteristics of real materials to be directly implemented using the filter coefficients of each digital surface absorption filter. This enables virtual acoustic spaces to be designed quickly without the need for the digital reverberator to be manually tuned for each space.

Abstract: Embodiments of the invention improve upon the prior art array by having more carefully defined directivity functions designed to meet two criteria, being firstly to minimise cross-talk between non-adjacent microphones in the array, and secondly to design the array response such that it approximates stereophonic panning curves that have been shown to provided for good auditory localisation. One embodiment therefore provides a microphone array, comprising N microphones, wherein N is greater than or equal to 3. The microphones are substantially equiangularly arranged over a circular arc subtending an angle ?, wherein ? is less than or equal to 2?, with the directional axes of the N microphones facing substantially radially outwards.

Abstract: A method of separating a mixture of acoustic signals from a plurality of sources comprises: providing pressure signals indicative of time-varying acoustic pressure in the mixture; defining a series of time windows; and for each time window: a) providing from the pressure signals a series of sample values of measured directional pressure gradient; b) identifying different frequency components of the pressure signals c) for each frequency component defining an associated direction; and d) from the frequency components and their associated directions generating a separated signal for one of the sources.