Hearing aid digital filter

A digital hearing aid uses a digital filter using coefficient multipliers and with digital signal processing algorithms, which can be implemented with a minimum amount of dedicated circuitry, which may be contained in an integrated circuit. Power consumption in the digital hearing aid is kept to a minimum by the use of a single, general purpose multiplier by eliminating a multiplexed multiplier, and by eliminating a plurality of general purpose multipliers. Preferably, filter coefficients which are limited to powers of 2 are used in the digital filter, whereby coefficient multipliers function as shifters. Shifting-hardware is simpler and more economical compared to a multiplier. Multiplication by powers of 2 is implemented by circuit connections in the hearing aid circuitry, without requiring any power expenditure from the battery. The digital filter may be a non-recursive finite impulse response (FIR) digital filter, or, an infinite impulse response (IIR) digital filter.