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Compression RatioSingle-band CompressionMultiband CompressionSliding-band Compression5102030Comparison of dynamic range compression using single-band, multiband, and sliding-band compression schemesSpeech materialyou will mark ut please concatenated with scaling factors of 0.1, 0.8, 0.1, 0.4, 0.1ProcessingSingle-band, multiband, and sliding-band dynamic range compression using Win. len. = 25.6 ms, FFT len. = 512

Results from offline processingnitya@ee.iitb.ac.inEE Dept., IIT Bombay

Time (s)

Distortions during spectral transitions: Example of swept sinusoidal input. Sliding band compression outputMultiband compression (18 auditory critical bands) outputSingle-band compression outputInput: constant amplitude, 125 250 Hz linearly swept frequency, 200 ms sweep durationCR = 30, Ta = 6.4 ms, Tr = 192 ms. nitya@ee.iitb.ac.inEE Dept., IIT BombayExample: "you will mark ut please" concatenated with scaling factors for variation in the input level. CR = 2, Ta = 6.4 ms, Tr = 6.4 & 192 ms.

Input waveform Scaling factor Unprocessed waveform Processed Tr = 6.4 ms, low Pmc Processed Tr = 192 ms, low Pmc Processed Tr = 6.4 ms, high Pmc Processed Tr = 192 ms, high Pmc

Time (s)

Processing of different speech materials with varying levels: No audible roughness or distortion during informal listening.nitya@ee.iitb.ac.inEE Dept., IIT BombayResults from real-time processingInformal listening: real-time output perceptually similar to the offline outputPESQ for real-time w.r.t. offline : 3.5Signal delay = 36 msUse of processing capacity: 41% (lowest proc. clock for satisfactory operation = 50 MHz, max. clock = 120 MHz)

Unprocessed waveform Offline processed waveformReal-time processed waveform

Example: "you will mark ut please" concatenated with scaling factors for variation in the input level. CR = 2, Ta = 6.4 ms, Tr = 192 ms, low Pmc.Time (s)nitya@ee.iitb.ac.inEE Dept., IIT Bombay