The first thing to be done is clustering the masking thresholds in the frequency, so that quantization step sizes do not take too many bits. This is often done in critical bands. This coder uses 24 slightly adjusted critical bands, in each of which the amplitude mean of the masking threshold is used as quantization step size. The bands were adjusted to better use the total clipping which often occurs at high frequencies, due to the ATH.
The table shows the clustering of the frequency bins into bands. The ``Coefficient ratio'' column is described below for stationary coding mode.