ABSTRACT

This chapter discusses the application of multiband compression (MBC) to the compensation of loudness recruitment. This technology was “reinvented” at Bell Labs between 1983 and 1987 and is sold by the ReSound Corporation. The chapter describes why MBC works, what the hair cells do, and how they do it, in lay terms. Using the experimental multiband compression hearing aid, Villchur experimented on hearing-impaired individuals, and found that Steinberg and Gardner’s predictions were correct. The chapter reviews the history of the Bell Labs hearing aid development. After solving many difficult practical problems, Fred Waldhauer’s newly formed ReSound team was successful in finalizing the analogue compression processing chip that is the heart of the ReSound hearing aid. The model of hearing and hearing loss, along with the loudness models of Fletcher, are basic to an eventual quantitative understanding of cochlear signal processing and the cochlea’s role in detection, masking, and loudness in normal and impaired ears.