8. Speech perception Flashcards Preview

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Flashcards in 8. Speech perception Deck (17):
1

McGurk effect

Ba and Va sound the same with eyes closed

Only lip reading and mouth shape help us to distinguish them

2

How do we divide speech (speech segmentation)

Possible word constraint: use knowledge of words to match what we hear to words we know and make sense

Coarticulation: helps predict what is coming next.
MORE coarticulation WITHIN a word than between

Segmentation (syllable based or stress based)
Syllable- recognise familiar, clear syllables
Stress- emphasise certain syllables

3

Categorical perception

Ambiguous phonemes are categorised as one or the other with an abrupt boundary

Phoneme categories vary between languages so much so that some do not sound different to us while they are distinct categories for others

4

Babies categorical perception

Babies can discriminate between phoneme categories of ALL language until 10-72 months old and then only their native language ones

Adults can only hear their own language

5

Mattys et al 2005
Hierarchical approach to segmentation

Combines all cues together

Tier 1- lexical. OPTIMAL
Semantic context based on lexical knowledge

SUBLEXICAL
Tier 2- segmental (poor lexical info)
Phonetics and co articulation

Tier 3. Metrical prosody (poor segmental info)
Words stress

6

Lexical identification shift

Ganong 1980
Varied ambiguous phoneme along continuum from k to g
Inserted this infront of word ending 'iss'

Found that k was identified sooner as it's matched to make a real word
(Context affects perceptual changeover point)

Ambiguous initial phonemes are more likely to be assigned a phoneme category when doing so produces a word

7

Sentence context

Used to help us guess at words or used as a segmentation cue

Eg. Lovers are meant to ADORE each other
The hallway leads to A DOOR at the end

8

Context phoneme restoration effect

First phoneme of a word in a sentence replaced by a cough

The word heard changed depending on the context of the sentence

Eg.
The *eel was on the axle
The *eel was on the shoe
The *eel was on the orange

Sentence context has an INDIRECT effect involving guessing the identity of the missing phoneme

9

Cohort model of speech perception

3 stages:

1. ACCESS STAGE - perceptual representation used to generate a whole list of words
2. SELECTION STAGE- 1 item is chosen from the set (narrowed down as more sounds are available and sentence context etc used)
3. INTEGRATION STAGE - Semantic properties used to integrate it into the sentence

UNIQUENESS POINT- where there is only one possible word left that it can be

PARALLEL and interactive processing. Phoneme and lexical and semantics used at the same time to get to uniqueness point

More emphasis on bottom up processing

10

Isolation point

Point in a word where listeners identify it correctly

Usually earlier than uniqueness point but may be wrong

11

Lexical access

Point at which all information about a word (phonological, semantic, syntactic) become available following recognition

12

Fluent restorations

When listening to a sentence with an error. Asked to repeat it back as quickly as possible and 50% of the time the error is corrected automatically

13

Mispronunciations

Participants are more sensitive to changes at the beginning of a word

14

TRACE model

Interaction of bottom up and top down processing

Bottom up activation - from acoustics > phoneme > word

Top down activation- word> phoneme > acoustic feature


There are inhibitory connections between units within each level, once activated it inhibits competitors

EMPHASISES TOP DOWN processing
Lexical context can directly effect acoustic perceptual processing

15

Evidence for top down processing

Lexical identification shift

Word superiority: phonemes detected faster when presented in the context of words rather than non words

Frequency effect: faster identification of common words

16

Egocentric heuristic

Listeners interpret what they hear based on own knowledge rather than knowledge the share with the speaker

17

Problems faced in speech perception

Speed- over 10 phonemes per second, we can cope with up to 50-60

Voices and accents

Invariance - words may sound different depending on what comes before or after them = coarticulation

Degraded speech/ environmental noise

Speech segmentation - knowing when a word starts and ends, not alert breaks during speech.. Pseudo breaks of silent letters