Signal Processing Algorithms for a new, Software-based, Digital Hearing Device

The basic function of a hearing device is to make sounds audible, yet not uncomfortably loud for the user. Furthermore, improvement of the signal to noise ratio (SNR) in difficult listening situations and effective feedback control schemes are important to both the hearing impaired patient and the hearing health care professional fitting the hearing device. The algorithms developed for the ReSound digital processor, taken together, make up a system that not only compensates for hearing loss and loudness recruitment, but also attempts to address the problems of feedback and speech understanding in noise. This article provides a functional description of these processing schemes and the basic building block for the compression and noise reduction algorithms, the Fast Fourier Transform (FFT).