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-25 o. 0 o. +25 o. left. left. left. right. right. right. room 1l08. room 155. room 157. 12. 12. 12. 12. 12. 12. 12. 12. 12. 12. 12. C 50 , dB. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 2.5. 2.5. 2.5. 2.5. 2.5. 2.5. 10. 10. 10. 10. 10. 10. corridor. L-shaped.
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-25o 0o +25o left left left right right right room 1l08 room 155 room 157 12 12 12 12 12 12 12 12 12 12 12 C50, dB 0 0 0 0 0 0 0 0 0 0 0 2.5 2.5 2.5 2.5 2.5 2.5 10 10 10 10 10 10 corridor L-shaped distance, m (log scale)
Some further data on ‘wide-band scn’ contexts scn is speech → noise operation is performed on the wide-band signal (unlike the vocoder manipulations) reverse polarity of a randomly-selected half of the samples, then apply a speech-shaping filter ‘noise before’ conditions: room impulse response (BRIR) applied after the scn operation in this condition of Watkins, 2005, expt. 4: no effect of test-word’s reverb.
This experiment similar except: ‘to click on ‘ part of the context stays as speech in ‘noise before’ conditions monaural (left ear) stressed (slow) test-words and context speech looks at the effect of a context-length (685 ms) gap preceding the test-word 4 observations per stimulus from each of 6 listeners L-shaped room, as before
no gap gap • compensation effect with speech • gap reduces the effect, but it’s not entirely eliminated • effect is marginal or absent in noise (before) conditions • no influence from ‘to click on’ 10 speech 5 0 category boundary, step test dist.=10. m test dist.=.32 m noise (before) 10 5 0 context’s distance, m .32 .32 10. 10.
Temporal envelopes of context and test-word in an auditory (gammatone) filter, fc= 4.2 kHz • as reverb increases, mean increases • but this effect is if anything more apparent with the noise context 10. m 0.32 m speech amplitude re. max 1 1 noise (before) 0 0 1 0 0 1 time, s
Is temporal structure of reverb pattern important? forwards reversed • 8-band vocoder, one channel: • if scn comes after the BRIR operation • temporal structure is scrambled • e.g. as measured by autocorrelation: • consider a single reflection • scn flattens its combfilter spectrum speech → → scn → → gammatonegammatone BRIR
unprocessed speech 4-,8-band mismatched 4-,8-band matched mismatched, both groups group 1 context test word matched, group 2 category boundary, step matched, group 1 test dist.=10. m test dist.=.32 m 10 10 group 2 category boundaries higher than in mismatched 5 5 could well be an inverse filter effect if even bands have more info about the [t] … 0 0 .32 .32 .32 10. 10. 10. context’s distance, m
Inverse-filter effects with wideband (smother) temporal envelope? forwards reversed scn → → scn → → gammatonegammatone • replace speech input with wideband scn • 8-band vocoder, one channel: BRIR
Band importance experiments using compensation effect, rather effects of reverb on the test-word.