Digital hearing aids utilize digital signal processing (DSP) chips, which became available in 1982. Experimental body-worn digital hearing aids were developed soon after.
Project Phoenix was established in 1984 and commercially produced the first wearable DSP hearing aid in 1988. Unfortunately, it was large (the combined size of a body aid and a behind-the-ear aid) and expensive and thus not a financial success. As recently as April 1996, the first fully digital behind-the-ear and in-the-ear instruments were made commercially available with a computing capacity of 40 million instructions per second. Digital hearing aids operate on either an open or closed platform (more or less flexibility) dependent upon the manufacturer.
As technology continued to improve, digital programmable hearing aids were developed. This latest development has given us hearing aids that are capable of adjusting to sound input on their own, thus eliminating the need for a separate remote control. These hearing aids look no different from transistor hearing aids, and are available from behind-the-ear styles down to completely-in-the-canal styles. Often these hearing aids have a push-button volume control or no volume control; the hearing aid adjusts itself as needed depending on the listening environment.
The current era of DSP and programmable hearing aids holds promise for increased sound quality and maximum flexibility in fulfilling the unique needs of the hearing impaired population.