Generation and evaluation of isolated audio coding artifacts

Many existing perceptual audio codec standards define only the bit stream syntax and associated decoder algorithms, but leave many degrees of freedom to the encoder design. For a systematic optimization of encoder parameters as well as for education and training of experienced test listeners, it is instrumental to provoke and subsequently assess individual coding artifact types in an isolated fashion with controllable strength. The approach presented in this paper consists of a pre-selection of suitable test audio content in combination with forcing a specially modified encoder into non-common operation modes to willingly generate controlled coding artifacts. In conclusion, subjective listening tests were conducted to assess the subjective quality for different parameters and test content.