distance, m (log scale)

0

12

0

12

0

12

0

12

0

12

0

12

0

12

0

12

0

12

0

12

0

12

left right left right left right-25

o0

o+25

o

102.5 102.5 102.5 102.5

102.5 102.5

C50

, dB

L-shaped

corridor

room 1l08

room 155

room 157

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

context’s distance, m

cate

gory

bou

ndar

y, s

tep

.32 10. .32 10.

0

5

10

0

5

10

no gap

test dist.=10. m

test dist.=.32 m

gap

speech

noise

(before)

• 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’

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

+1

+.5

0

21.510.50

time, s

21.510.50

time, s

+1

+.5

0

21.510.50

time, s

21.510.50

time, s

noise

(before)

speech

0.32 m

10.

m

ampl

itude

re.

max

0

1

1

0

0

1

0

1

time, s

forwards reversed gammatone gammatonespeech → → scn → → BRI

R

• 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

Is temporal structure of reverb pattern important?

context’s distance, m

group2

group1

4-,8-bandmismatched

4-,8-bandmatched

unprocessedspeech

test dist.=10. m

test dist.=.32 m

.32 10. .32 10. .32 10.

cate

gory

bou

ndar

y, s

tep

0

5

10

0

5

10

mismatched, both groups

matched, group 1 matched, group 2

test wordcontext

category boundaries higher than in mismatched

could well be an inverse filter effect if even bands have more info about the [t] …

• replace speech input with wideband scn

• 8-band vocoder, one channel:

Inverse-filter effects with wideband (smother) temporal envelope?

forwards reversed gammatone gammatone scn → → scn → → BRI

R

Band importance experiments using compensation effect, rather effects of reverb on the test-word.