Digital processing of audio signals utilizing cosine functions

A non-transitory computer or device-readable medium including instructions for processing a digital signal, said instructions when executed by a processor cause said processor to:

• provide a digital filter represented by an impulse response of waveform components each being absolute values of a cosine function in the time domain limited to half a waveform cycle at its midpoint, said waveform components being summed across a relevant frequency range to produce the impulse response;
• increase the sample rate of the digital filter represented by the impulse response from a predetermined sample rate to an increased sample rate including intermediate sample points of the impulse response between adjacent sample points of the neighbouring sample points;
• and
• apply the digital filter represented by the impulse response to the digital signal;
• generate an analog signal representative of the filtered digital signal;
• and
• play back the analog signal.

A computer system for processing a digital signal, said system comprising a processor configured to:

• provide a digital filter represented by an impulse response of waveform components each being absolute values of a cosine function in the time domain limited to half a waveform cycle at its midpoint, said waveform components being summed across a relevant frequency range to produce the impulse response;
• increase the sample rate of the digital filter from a predetermined sample rate to an increased sample rate including intermediate sample points of the impulse response between adjacent sample points of the neighbouring sample points;
• and
• apply the digital filter represented by the impulse response to the digital signal;
• generate an analog signal representative of the filtered digital signal;
• and
• play back the analog signal.