Clinical results of a 15-filter digital auditory prosthesis using selective amplification and compression

Classical hearing aid efficiency was compared with that of a 15-filter digital auditory prosthesis in 23 patients suffering from partial sensorineural hearing loss. This device contains a microprocessor 320C25 from TEXAS Instruments. The sound signal is analysed at a sampling rate of 16 kHz. With the use of a Fast Fourier Transform (FFT), it provides the system with 15 energy levels at frequencies ranging from 0 to 8 kHz. The energy of each frequency band is multiplied by a coefficient stored in the device memory and directly dependent on the patient's audiometric specificities. The 15 signals are then synthesized by inverse FFT and mixed in a loudspeaker. The prosthesis is a rechargable battery powered 4 x 10 x 15 cm box programmable through a PC. The clinical results obtained with this 15-filter digital prosthesis are discussed and compared with the performances of present classical hearing aids.