Adapting television soundtracks for listeners with hearing loss

Conventional dynamic range compression, while widely used to restore audibility, often introduces artefacts such as pumping, distortion, and loss of natural timbre. The project explores alternative approaches, guided by auditory modelling, aiming to restore audibility while minimising perceptual side effects.<br><br>A framework was developed comprising an analysis stage, adaptation stage, and resynthesis.

Input audio was decomposed using a complex gammatone filterbank, from which amplitude envelopes were derived. Envelopes were compared against both normal hearing thresholds and the thresholds of a model hearing loss to guide the amplification, local in both time and frequency. The implementation of smooth spectrotemporal amplification was achieved using a novel method, the Slow Inverse Fourier Transform, enabling reconstruction of time-domain signals after adaptation.<br><br>To gauge the extent to which quieter components of TV soundtracks needed their audibility to be preserved, a binary masking analysis was performed, removing elements deemed less perceptually significant according to a phons-based threshold.