Advances in Perceptual Bass Extension for Music and Cinematic Content

“Small-form factor and thin devices exhibit a high-pass frequency response due to loudspeaker-enclosure constraints. The low-frequency reproduction loss from these devices severely degrades the audio experience for music and cinematic content. In this paper, we present a new perceptual bass extension model using a side chain for music and cinematic content and leveraging the principle of the missing fundamental frequency. Optimizing the nonlinear function parameters enables the nonlinear function output to be invariant to input signal level changes. The model employs a unique input gain normalization scheme based on loudness metadata and level-matching between multiple side chains. A loudness compensation algorithm restores the perception of the loss of bass, particularly at low playback levels. Subjective testing and perceptually derived objective metrics using television (TV) loudspeakers validate the performance of the approach. “