The extension of classical frequency domain and wavelet transformation adaptive subband decompositions result in arbitrary time frequency TIL. The use of a time-varying tree-structured filterbank is proposed to provide a signal dependent transform which is capable of tracking non-stationarities via local reconfigurations. Under stationary assumptions, the filterbank converges to a unitary operator. The time-frequency information can then be used to reduce the model order thereby reducing computational complexity. A unique framework will be developed to unify the time-frequency, signal subspace, and basis vector representation viewpoints within adaptive subband decompositions.