Analysis filter bank and computing procedure thereof, audio frequency shifting system, and audio frequency shifting procedure

A filter bank computing procedure corresponding to a plurality of sub-bands, comprising the following steps:

• performing a plurality of complex-type first-order IIR filtering operations with different center frequencies on an input signal to obtain a plurality of sub-filtered signals;
• selecting a plurality of first subsets of the sub-filtered signals, wherein each of the first subsets corresponding to one of the sub-bands contains a first number of the sub-filtered signals obtained from the first number of the filtering operations adjacent in center frequency, and for each of the first subsets, performing a weighted-sum operation on a plurality of instantaneous values of the first number of the sub-filtered signals in the subset at each sample period with a first set of binomial weights to obtain one of a plurality of sub-band signals;
• selecting a plurality of second subsets of the sub-filtered signals, wherein each of the second subsets corresponding to a lower-frequency side or a higher-frequency side of one of the sub-bands contains a second number of the sub-filtered signals obtained by the second number of the filtering operations adjacent in center frequency, and for each of the second subsets, performing a weighted-sum operation on a plurality of instantaneous values of the second number of the sub-filtered signals in the subset at each sample period with a second set of binomial weights to obtain one of a plurality of lower sub-band-edge signals or one of a plurality of higher sub-band-edge signals;
• and
• performing a plurality of envelope detection with decimation operations on the sub-band signals, the lower sub-band-edge signals, and the higher sub-band-edge signals to obtain at least one fine spectrum.