An apparatus for processing an audio signal, the apparatus comprising: a low delay decimated analysis filter bank comprising M analysis filters, wherein M is greater than 1 and wherein the M analysis filters are modulated versions of an asymmetric prototype filter p 0 (n) having a length N; wherein M = 64 and N = 640; and a low delay decimated synthesis filter bank comprising M synthesis filters, wherein the M synthesis filters are modulated versions of the asymmetric prototype filter p 0 (n); wherein the apparatus is configured to: obtain a plurality of subband signals by filtering the audio signal with the M analysis filters, wherein the filtering comprises applying, to arrays of 128 samples derived from the audio signal, a complex-exponential modulation matrix of the form: M A k l = exp j π 128 k + 1 2 * 2 l + 129, 0 ≤ k < M, 0 ≤ l < 128 process the plurality of subband signals to generate a plurality of processed subband signals; and obtain a processed audio signal by filtering the plurality of processed subband signals with the M synthesis filters, wherein the filtering comprises applying, to arrays of M samples derived from the plurality of processed subband signals, a complex-exponential modulation matrix of the form: M S k l = 1 64 exp j π 128 k + 1 2 2 l − 255, 0 ≤ k < M, 0 ≤ l < 128. a low delay decimated analysis filter bank comprising M analysis filters, wherein M is greater than 1 and wherein the M analysis filters are modulated versions of an asymmetric prototype filter p 0 (n) having a length N; wherein M = 64 and N = 640; and a low delay decimated synthesis filter bank comprising M synthesis filters, wherein the M synthesis filters are modulated versions of the asymmetric prototype filter p 0 (n); wherein the apparatus is configured to: obtain a plurality of subband signals by filtering the audio signal with the M analysis filters, wherein the filtering comprises applying, to arrays of 128 samples derived from the audio signal, a complex-exponential modulation matrix of the form: M A k l = exp j π 128 k + 1 2 * 2 l + 129, 0 ≤ k < M, 0 ≤ l < 128 process the plurality of subband signals to generate a plurality of processed subband signals; and obtain a processed audio signal by filtering the plurality of processed subband signals with the M synthesis filters, wherein the filtering comprises applying, to arrays of M samples derived from the plurality of processed subband signals, a complex-exponential modulation matrix of the form: M S k l = 1 64 exp j π 128 k + 1 2 2 l − 255, 0 ≤ k < M, 0 ≤ l < 128. obtain a plurality of subband signals by filtering the audio signal with the M analysis filters, wherein the filtering comprises applying, to arrays of 128 samples derived from the audio signal, a complex-exponential modulation matrix of the form: M A k l = exp j π 128 k + 1 2 * 2 l + 129, 0 ≤ k < M, 0 ≤ l < 128 process the plurality of subband signals to generate a plurality of processed subband signals; and obtain a processed audio signal by filtering the plurality of processed subband signals with the M synthesis filters, wherein the filtering comprises applying, to arrays of M samples derived from the plurality of processed subband signals, a complex-exponential modulation matrix of the form: M S k l = 1 64 exp j π 128 k + 1 2 2 l − 255, 0 ≤ k < M, 0 ≤ l < 128.