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Cognitive Psychology > speech perception > Flashcards

speech perception Flashcards

1
Q

challenges of speech perception

A
  • no clear gaps between words
  • co-articulation: acoustic realisation on speech depends on what you’ve just said and what you are about to say > the same words can come out differently each time

also pronunciation varies from speaker to speaker, accents, etc

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2
Q

how do we produce speech

A
  • lungs push air up the trachea
  • which vibrate the vocal cords in the larynx
  • sounds from the vocal cords are then shaped by the supraryngeal vocal tract
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3
Q

labial consonants

A

lips used/touch

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4
Q

alveolar consonants

A

tongue touches behind teeth

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5
Q

velar consonants

A

tongue toches back of mount

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6
Q

stop

A

air flow stops completely

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7
Q

voice

A

when you say them vocal cords vibrate

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8
Q

unvoiced

A

no vibration

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9
Q

fricative

A

constriction does not happen completely, friction involved

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10
Q

nasal

A

airflow redirected to nasal cavity

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11
Q

sound waves

A
  • periodic displacement of air molecules, creating increases and decreases in air pressure
  • when we plot changes of sound pressure over time
  • molecules come closer or further apart - inc and decr pressure

–> forming waveforms

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12
Q

spectograms

A

split sound into different frequencies at each moment

amplitude: indicated by colour

  • splits info into different frequency channels - depicts info that the brain gets
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13
Q

source and filter theory

A

source: the vibrations of the vocal cords

filter: superlaryngeal vocal tract structure that shapes the sound produced by the source

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14
Q

source only

A

can maybe interpret whether sound is a question? or a statement.

the gender, happy or sad

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15
Q

source AND filter

A
  • intelligible speech
  • filter (supralaryngeal vocal tract, lips, teeth) important for sounds - PHONEMES
  • filtering appears as band of energy at certain frequencies in spectrograms Called FORMANTS
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16
Q

lowest three formants

A

F1 F2 F3

these are important cues for identifying vowels

  • brain can know which vowel it is hearing by detecting these auditory CUES
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17
Q

formants for vowels

A

F1 F2 F3

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18
Q

formants for consonants

A

F2 F3

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19
Q

CATERGORICAL PERCEPTION
DEMONSTRATION

A

demonstrated:
continuum of sounds ‘ba’

one end: one sound
other end: another sound ‘da’

middle: sound that is ambiguous between the two cues

  • task: where they heard each sound

1st signature of categorical perception = PHONEME BOUNDARY - where ps are equally likely to respond ba as da

20
Q

1st signature of categorical perception

A

Phoneme boundary: where participants are equally likely to respond ‘ba’ than ‘da’

21
Q

2nd signature of categorical perception

A
  • discrimination peak near the phoning boundary
22
Q

CATEGORICAL PERCEPTION

A

the tendency to perceive gradual sensory changes in a discrete fashion

23
Q

3 hallmarks of categorical perception

A
  1. abrupt change in identification at phoneme boundary
  2. discrimination peak at phoneme boundary
  3. discrimination predicted from identification (only sound ‘different’ if different phoneme
24
Q

context affects

A
  • speech perception depends on prior knowledge and contexts

‘McGurk effect’: lipreading with different sound - what we hear is changed by what we see

25
Q

McGurk effect

A

‘McGurk effect’: lipreading with different sound - what we hear is changed by what we see

26
Q

Ganong effect

A
  • continuum paradigm
  • use the same sound but tell people its ‘giss’ to ‘kiss’ or ‘gift’ to ‘ kift’

bias to k and g changes for the one that is the real word

27
Q

motor theory of speech perception

LIBERMAN

Component 1

A
  • speech perception = result of specialised speech module that operates separately from the mechanisms involved in perceived non-speech sounds

AND is UNIQUELY HUMAN

EVIDENCE: Speech and not other sounds are perceived categorically e.g. yanny OR laurel - not both

basically be proven wrong

28
Q

motor theory of speech perception

LIBERMAN

Component 2

A
  • The objects of speech perception are intended articulatory events rather than acoustic events

EVIDENCE: speech sounds are highly variable

we are interpreting gestures rather than sounds

may still be right

29
Q

motor theory fMRI evidence FOR

A

task: listen to meaningless monosyllables

outcome: auditory cortex activated (audio is being processed)

BUT

motor and premotor areas are also activated which is evidence for us interpreting sound gesturally

30
Q

motor theory TMS evidence FOR

A
  • TMS over premotor areas interferes with phoneme discrimination in noise but not colour discrimination

MOTOR AREAS ARE CAUSALLY INVOLVED IN SPEECH PERCEPTION

31
Q

motor theory evidence AGAINST

A
  • categorical perception can also be demonstrated for non-speech sounds (e.g. musical intervals)

> so not a result of a specialised speech module

  • with training chinchillas show the same phoneme boundary for da/ta continuum as humans > not uniquely human
32
Q

classic model of brain basis of speech perception

A
  • superior temporal gyrus for speech perception (Wernicke’s area)
  • inferior frontal gyrus for speech production (Broca’s area)
  • left hemisphere dominant
33
Q

more up to date model of brain basis of speech perception: dorsal and ventral streams

A
  • 2 streams for speech processing that are engaged in a task dependent manner

dorsal stream: mapping speech sounds onto articulatory representations - activated for tasks focusing on perception of speech sounds - e.g. phoneme perception

ventral stream:
mapping speech sounds onto lexical representations - activated for tasks focussing on comprehension e.g. word recognition

  • can explain why some aphasics can’t tell apart phonemes but can recognise words and vice versa
34
Q

dorsal stream - brain basis or speech perception

A
  • mapping speech sounds onto articulatory representations
  • activated for tasks focusing on perception of speech sounds - e.g. phoneme perception
  • left hemisphere dominant
  • Broca’s area = involved in perception NOT JUST PRODUCTION
35
Q

ventral stream - brain basis or speech perception

A
  • mapping speech sounds onto lexical representations
  • activated for tasks focussing on comprehension e.g. word recognition
  • bilateral - left AND right hemispheres
36
Q

evidence for ventral stream processing

A
  • anterior temporal damage associated with semantic impairment (ventral)

inferior temporal damage associated with comprehension deficits (ventral)

37
Q

evidence for dorsal stream processing

A
  • listening to syllables activates motor and premotor areas (dorsal)
  • TMS over premotor areas interferes with phoneme discrimination in noise but nor colour discrimination (dorsal)
38
Q

process of recognising spoken words: cohort model

A
  • set of word representations in your mind - what words should sound like - lexicum
  • if you hear ‘c’ all words in lexicum that start with the sound ‘c’
  • as time goes on and you hear more and more of the word - less potential words are activated

until… UNIQUENESS POINT:
time-point in the speech when inly one word become consistent with the speech input > word is recognised at UP even before whole word is produced

39
Q

uniqueness point

A

time-point in the speech when inly one word become consistent with the speech input > word is recognised at UP even before whole word is produced = optimal efficiency

40
Q

key features of cohort model

A
  • words are activated immediately upon minimal input
  • multiple words are activated
  • words compete for recognition - lexical competition
41
Q

cohort model: evidence from shadowing task

A
  • average response latency was 250ms
  • average duration of words was 375ms
  • recognising at uniqueness point
42
Q

limitations of cohort model

A
  • verbal model
  • so hard to evaluate
  • solution: a computer model
43
Q

TRACE computer model of speech perception

A

words

phonemes

acoustic features

  • connections between levels are bi-directional and excitatory (TOP-DOWN EFFECTS)
  • connections within levels are inhibitory producing competition between alternatives
44
Q

TRACE model from eye tracking

A
  • task: take one item and move it to a different location

as more of spoken word of object is revealed, the more they start to look at the object and even rhyming/similar named objects

can put this into a computer - similar results mean human trials are doing a good job at modelling dynamics

45
Q

TRACE and context

A

for the gift kiss kift giss

  • if you hear a sound in context of the rest of the word - you are biased to that because you recognise it thats why if told ist- gist is preferred and i told -iss kiss is preferred

Cognitive Psychology (13 decks)

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