An investigation into different masking behaviours resulting from estimation of tonality index

A psychoacoustics model that approximates the masking threshold is presented. The significance of the tonality index is highlighted by comparing two well-known methods used in its estimation: unpredictability and spectral flatness measure. The first method has a tendency to give a lower threshold in the low frequency (below 3 kHz) region whereas the second one tends to be lower in the high frequency range. A new method is proposed which combines both techniques to achieve better results. This technique moderates the complexity of the two earlier methods and increases the compression ratio considerably without compromising the audio quality.