PhD thesis

AuthorThilo Thiede
TitlePerceptual Audio Quality Assessment using a Non-Linear Filter Bank
TutorProf. Noll
AbstractThis thesis describes a new method for the objective measurement of perceived audio quality. The method is based on a non-linear filter bank which provides a good approximation of auditory filter shapes and even models the level dependence of these filter characteristics. Unlike other measurement schemes, the quality estimation is not solely based on models for steady-state signals, but considers also the temporal structure of the envelopes of the auditory filter outputs. A further improvement compared to other measurement methods is a separation between linear and nonlinear distortions. This takes into account the fact that imbalances in the frequency response of an audio device are less annoying than the same amount of non-linear distortions like, for example, quantisation noise. The computational complexity of the filter bank implemented in this method is lower than for most other filter banks applicable to perceptual measurement. The method has proven to be superior to most other measurement methods used in this field and a large part of it will be included in the ITU-recommendation „method for objective measurements of perceived audio quality“. Especially the part of this recommendation that addresses applications requiring maximum possible accuracy („advanced version“) is mainly based on this method.