Temporal processingRepresentation of the temporal

characteristics of sound

Temporal variation in sound carries important information

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Different measures of temporal processing mature at different rates Gap detection Duration discrimination Forward and backward masking Temporal modulation transfer function

Gap detection

Time (ms)

Lev

el (

dB

)

Time (ms)

Lev

el (

dB

)

Interval 1 Interval 2

Which one had a gap?

Gap detection for infants

Time (ms)

Lev

el (

dB

)

Adult gap detection depends on frequency

Gap detection by infants: Werner et al. (1992)

Frequency (Hz)

Leve

l (dB

)

Time (ms)

Lev

el (

dB

)

Time (ms)

Lev

el (

dB

)

Gap detection by infants: Werner et al. (1992)

Gap detection by children: Irwin et al. (1985)

Gap detection by children: Wightman et al. (1988)

Detecting gaps between Gaussian shaped tone bursts

Gap detection between Gaussian shaped tone bursts

Summary of gap detection

Duration discrimination

Susceptibility to adaptation

Adaptation

Recovery

Susceptibility to adaptation

Forward masking as a measure of susceptibility to adaptation

Adaptation

Recovery

TimeAm

plitu

de

Forward masking: Infants

Forward masking: Children

Backward masking

TimeAm

plitu

de

Backward masking: Infants

0.5

0.6

0.7

0.8

0.9

1

15 25 35 45 55 65 75 85 95

p(C

)

Level (dB SPL)

Infants

Adults

Infant unmaskedthreshold

adult unmaskedthreshold

Backward masking: Children

Amplitude modulation: frequency and depth

-1.5

-1

-0.5

0

0.5

1

1.5

0 0.05 0.1 0.15Time (s)

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

0 0.05 0.1 0.15

-1.5

-1

-0.5

0

0.5

1

1.5

0 0.05 0.1 0.15

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

0 0.05 0.1 0.15

10 Hz10 Hz

20 Hz

100%, 0 dB 25%, -12 dB

Temporal modulation transfer function

TMTF: Infants

0

-5

-10

-15

-20

-25

1 10 100 512

Mod

ulat

ion

dept

h, 2

0 lo

g m

(dB

)

Modulation frequency (Hz)

adults

3-month-olds6-month-olds

TMTF: Children

Summary of results on different measures Gap detection: mature at 6 years Duration discrimination: mature at 10 years Forward masking: mature at 6 months Backward masking: mature at 11 years TMTF: mature at 4 years (3 months?)

SummaryThere doesn’t seem to be one age at

which all sorts of temporal processing are mature

Possible additional contributors to immature temporal processing Intensity resolution Memory Confusion Decision strategy