Theoretical analysis and perceptual evaluations on nonlinear devices in virtual bass system

• Main Author: Oo, Nay
• Other Authors: Gan Woon Seng
• Format: Theses and Dissertations
• Language: English
• Published: 2012
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Applications of electronics
• Online Access: https://hdl.handle.net/10356/48236
• Institution: Nanyang Technological University

With the development of small consumer audio-enabled devices, such as mobile phones, tablet computers, light-weight laptop computers, and flat-panel televisions, the demand to reproduce good bass sounds with inherently small loudspeakers has never been greater. Enhancement of bass sounds by simply amplifying low frequency audio components does not work well, and may even overload and damage small loudspeakers. Thus, due to the limitations of miniature loudspeakers, physical bass enhancement is impossible without using bulky subwoofers. However, an alternative way to enhance bass is by tricking our human auditory system into perceiving fuller bass sounds. This is called the psychoacoustic bass enhancement system, or virtual bass system (VBS). By making use of the phenomenon known as the “missing fundamental,” by which our auditory system reconstructs the fundamental frequency (virtual pitch) from harmonics even if the fundamental frequency is completely missing, we can trick our ears to hear low frequencies, which cannot be efficiently reproduced by the small loudspeakers, from their higher harmonics, which are carefully injected into the original audio signal stream and situated in the mid-frequency range where loudspeakers can reproduce them well. Thus, physical bass frequencies that cannot be reproduced by small loudspeakers can be replaced by the perception of psychoacoustic bass frequencies that is synthesized in the human auditory system, thereby extending the experience of low-frequency bandwidth for listeners.