An efficient reverberator structure is proposed for approximating measured reverberation. A fixed convolution matching the early portion of a measured impulse response is crossfaded with a switched convolution reverberator drawing its switched convolution section from the late-field of the measured impulse response. In this way, the early portion of the measured impulse response is precisely reproduced, and the late-field equalization and decay rates efficiently approximated. To use segments of the measured impulse response, the switched convolution structure is modified to include a normalization filter to account for the decay of the late-field between the nominal fixed/switched crossfade time and the time of the selected segment. Further, the measured impulse response late-field is extended below its noise floor in anticipation of the normalization. This structure provides psychoacoustically accurate synthesis of the measured impulse response using less than half a second of convolution, irrespective of the length of the measured impulse response. In addition, the structure provides direct control over the equalization and late-field frequency dependent decay rate. Emulations of EMT 140 plate reverberator and marble lobby impulse responses are presented.

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User control over variable-rate time-stretching typically requires direct, manual adjustment of the time-dependent stretch rate. For time-stretching with transient preservation, rhythmic warping, rhythmic emphasis modification, or other effects that require additional timing constraints, however, direct manipulation is difficult. For a more user-friendly approach, we present work that allows a user to specify a time-dependent stiffness curve to warp the time axis of a recording, while maintaining other timing constraints, such as a desired overall recording length or musical rhythm quantization (e.g. straight-to-swing), providing a notion of stretchability to sound. To do so, the user-guided stiffness curve and timing constraints are translated into the desired time-dependent stretch rate via a constrained optimization program motivated by a physical spring system. Once the time-dependent stretch rate is computed, appropriately modified variable-rate time-stretch processors are used to process the sound. Initial results are demonstrated using both a phase-vocoder and pitch-synchronous overlap-add processor.

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