3308First Language acquisition

Acquisition of sounds

Perception

Sook Whan Cho

Fall, 2012

Questions onacquisition of sounds

- How do newborns perceive speech sounds?

- When and how do infants learn meaningful sound differences (phonemic contrasts) of the native language?

- When do infants learn sound combinations (phonotactics) of the native language?

- When and how do infants learn to pick out words from a speech stream?

운율의 표기

운율이 단조롭다면…

운율이 없다면…

“What did you say before that?”

합성 이전

“What did you say before that?”

합성 이후

합성 이전

합성 이후

Korean example

Prosody 운율

• 기본주파수 (fundamental frequency)

• 길이 (duration)

• 강도 (intensity)

기본주파수 (fundamental frequency)

Vibrations of vocal cords measured성대의 진동수 ( 단위 : Hz)

IntonationPitchStressTone

길이 duration

consonants/vowels/sentences

Measured by 1/1000 seconds ( 단위 : msec)

• 성대진동 개시구간 (voice onset time, VOT)

• 강세 (stress)

강도 intensity

Stress marking on consonants/vowels

Measured by dB (decibel)

English words with a stressed vowel

Categorical perception

We (= adults) perceive speech sounds as categories. Physically continuous acoustic differences are perceived as distinct groups of sounds.

Category A Category B

Voice onset time (VOT) and voicing

60 msec

Categorical perception of VOT

0

20

40

60

80

100

0 10 20 30 40 50 60

A VOT continuum is perceived as if it contains distincts sets of sounds. We hear the difference only around the boundary.

% id

entif

ied

as /d

/

0

20

40

60

80

100

0-20 10-30 20-40 30-50 40-60

% d

iscr

imin

ated

VOT VOT difference

0ms

20ms

40ms

20ms

40ms

60ms

D

D

T

D

T

T

Categorical perception of VOT

0

20

40

60

80

100

0 10 20 30 40 50 60

A VOT continuum is perceived as if it contains distincts sets of sounds. We hear the difference only around the boundary.

% id

entif

ied

as /d

/

0

20

40

60

80

100

0-20 10-30 20-40 30-50 40-60

% d

iscr

imin

ated

VOT VOT difference

0ms

20ms

40ms

20ms

40ms

60ms

D

D

T

D

T

T

Infants’ categorical perception of VOT

1-, 4-mos reaction to changes in VOT

High-amplitude sucking procedure

(Eimas et al, 1971)

No change40 ↔ 60ms20 ↔ 40ms