Abstract: The signal processing method includes the steps of: wavelet-transforming an input signal in a computer; and extracting features of the signal by Mellin-transforming the output of the wavelet transform step in synchrony with the input signal in a computer.

Abstract: A waveform to be analysed is spectrally resolved into a plurality of frequency channel outputs (1). Amplitudes of the channel outputs are then compared with threshold values (4), with the threshold values being varied in dependance on 1) previous amplitude detection in the same channel (13, 14, 15) and 2) amplitude detection in adjacent channels (16). In this way features introduced by the spectral resolution of the waveform may be filtered out along with unwanted noise. In addition, smearing due to compression of the output of the spectral resolution may be counteracted. Hence, the present invention is particularly useful in the analysis of sound waves and in speech recognition systems.

Abstract: Peaks are detected in the waveform and in response to the detection of peaks, successive segments of the waveform are sampled. The successive segments sampled are then summed with previously summed segments to produce a stabilized image of the waveform. The generation of the stabilized image is a data-driven process and one which is sensitive and responsive to periodic characteristics of the waveform and hence is particularly useful in the analysis of sound waves and in speech recognition systems.

Abstract: Existing auditory warning systems are in general too loud and it is often difficult to distinguish between a number of different warnings. Further under different conditions warnings may change character due to masking by varying noise. A warning system is disclosed which is based on a microprocessor and waveforms for each warning sound stored in a ROM. The waveforms are read out to DACs and used to drive a loudspeaker by way of programmable attenuators. Each waveform is devised to have at least four quasi-harmonically related frequency components at a power level in the range 15 to 30 dB above threshold. In this way the sounds are distinctive and do not change character with varying noise levels below threshold.

Abstract: Existing auditory warning systems are in general too loud and it is often difficult to distinguish between a number of different warnings. Further under different conditions warnings may change character due to masking by varying noise. A warning system is disclosed which is based on a microprocessor and waveforms for each warning sound stored in a ROM. The waveforms are read out to DACs and used to drive a loudspeaker by way of programmable attenuators. Each waveform is devised to have at least four quasi-harmonically related frequency components at a power level in the range 15 to 30 dB above threshold. In this way the sounds are distinctive and do not change character with varying noise levels below threshold.