Abstract: A directional signal processing system for beamforming information signals. The system includes an oversampled filterbank, which has an analysis filterbank for transforming the information signals in time domain into channel signals in transform domain, a synthesis filterbank and a signal processor. The signal processor processes the outputs of the analysis filterbank for beamforming the information signals. The synthesis filterbank transforms the outputs of the signal processor to a single information signal in time domain.

Abstract: A filterbank structure is provided which provides a flexible compromise between the conflicting goals of processing delay, filter sharpness, memory usage and band interaction. The filterbank has an adjustable number of bands and a stacking which provides for a selectable shift of band frequencies to one of two discrete sets of center frequencies. The width of the bands and hence the number of the bands is selected depending upon acceptable delay, memory usage, and processing speed required. The flexibility in terms of stacking of the bands provides twice the number of potential band edge placements, which is advantageous for hearing loss fitting especially at low frequencies. The same filter coefficients can be used for analysis and synthesis, to reduce memory usage.

Abstract: There is provided a method of controlling feedback in an acoustic system, for example a digital hearing aid, in which there is a potential feedback path between the output and the input. The method comprises making a spectral estimate of the input signal spectrum, and then subjecting the spectral estimate to a psycho-acoustic model to generate a control signal. A noise source is passed through a shaping filter, which is controlled with the control signal, to generate frequency-shaped noise, which is inaudible to someone hearing the output. The frequency-shaped noise is then added to the input signal to form a combined signal, which is processed in a forward path, to generate a first output signal. The first output signal and the frequency-shaped noise signal are analyzed, to determine the presence of feedback at difference frequencies, and the characteristics of the forward path are modified to reduce the gain thereof at frequencies where feedback is detected.

Abstract: An apparatus for a hearing aid provides an application specific integrated circuit (ASIC) for filtering of input signals and a programmable digital signal processor connected to it, for control of filterbank gains. This provides a compromise between the conflicting goals of size, re-programmability and power consumption. The fixed portion of the processing, i.e. filtering is implemented in hardware in the ASIC, and the variable or adjustable portion of the processing is implemented by the programmable digital signal processor. The filterbank has an adjustable number of channels and means for shifting the center frequencies of the bands in unison to one of two discrete sets of center frequencies. A wide range of hearing loss compensation schemes can be implemented. Software programs can be executed on the programmable digital signal processor.

Abstract: A filterbank structure is provided which provides a flexible compromise between the conflicting goals of processing delay, filter sharpness, memory usage and band interaction. The filterbank has an adjustable number of bands and a stacking which provides for a selectable shift of band frequencies to one of two discrete sets of center frequencies. The width of the bands and hence the number of the bands is selected depending upon acceptable delay, memory usage, and processing speed required. The flexibility in terms of stacking of the bands provides twice the number of potential band edge placements, which is advantageous for hearing loss fitting, especially at low frequencies. The same filter coefficients can be used for analysis and synthesis, to reduce memory usage.

Abstract: A method is provided for programming a digital hearing aid using a program encoded in an audio band (20 Hz-20 kHz) signal, to transmit and verify programs and algorithm parameters. Preferably, this is in a digital hearing aid including filterbanks, filtering the audio signal into different frequency bands. The signal is encoded by the presence and absence of a signal in each frequency band or by other well-known modulation techniques used by computer modems. Special programming signals are provided alternating between the frequency bands in a manner to clearly distinguish the program data from any other interfering or normally present audio signal. The method does not require additional hardware, and offers reduced power consumption, as compared to some known wireless programming interfaces. It enables remote programming over a network using standard multimedia computer hardware.