Task 9: Speech Perception

Question 1

What produces speech sounds?

Answer 1

position/movement of structures in vocal apparatus

Question 2

Acoustic signal

Answer 2

pressure changes in air

Question 3

Respiration

Answer 3

To generate an acoustic signal, air is pushed up from lungs past vocal cords and into vocal tract

Question 4

Phonation

Answer 4

Process through which vocal folds are made to vibrate when air pushes out of lungs. In fact, sound depends on shape of vocal tract as air is pushed through.

Question 5

Articulation

Answer 5

Shape of vocal tract is altered by moving articulators

Question 6

Articulators

Answer 6

Tongue, lips, teeth, jaw and soft palate.

Question 7

Resonance characteristics

Answer 7

 Changing size and shape of space through which sound passes increases and decreases energy at different frequencies

Question 8

How are vowels produced?

Answer 8

• Produced by vibration of vocal cords.
• Specific sounds of each cord are created by changing shape of vocal tract. By changing it, resonant frequency of vocal tract changes, producing peaks of pressure at different frequencies, called formants (F1 formant has highest frequency, F2 has next highest and so on)

Question 9

How are consonants produced?

Answer 9

• Produced by closing of vocal tract.
• Movement of tongue, lips and other articulators create patterns of energy in acoustic signal. Rapid shifts in frequency before or after formants (vowels) are called formant transitions and are associated with consonants (T1, T2).

Question 10

Sound spectrogram

Answer 10

Three-dimensional display that plots time on horizontal axis, frequency on vertical axis and amplitude (intensity) on color, with redder showing greater intensity, or gray scale.
- indicates patterns of frequencies and intensities that make up acoustic signal

Question 11

Phoneme

Answer 11

the shortest segment of speech that, if changed, changes meaning of word.

Question 12

What kind of relationship is between a phoneme and acoustic signal?

Answer 12

variable

Question 13

Coarticulation

Answer 13

the articulation of two or more speech sounds together, so that one influences the other.

Question 14

Perceptual constancy

Answer 14

We perceive sound of phoneme as same even if acoustic signal is changed by coarticulation.

Question 15

Discuss variability from different speakers x2

Answer 15

1. Individual differences – Some voices are high-pitched, other low-pitches, some talk rapidly, others slowly.
2. Sloppy pronunciation – When in conversational speech, people sometimes do not articulate each word individually.

Question 16

Name 3 ways speech perception systems deals with this variability problem in different ways (perceiving phonemes)

Answer 16

1. categorical perception
2. information provided by face/audiovisual speech perception
3. information from our knowledge of language

Question 17

Categorical perception (perceiving phonemes)

Answer 17

For speech and other complex sounds and images, it occurs when stimuli that exist along continuum are perceived as divided into discrete categories.

Question 18

Voice onset time (categorical perception)

Answer 18

Time delay between when sound begins and when vocal cords begin vibrating.

Example: /da/ has a short VOT and /ta/ has a long.

Question 19

Phonetic boundary (categorical perception)

Answer 19

Cross-over point from perception of one phoneme to another, depending on VOT.

Question 20

Name and explain 2 qualities defining categorical perception

Answer 20

1. Sharp labeling function – Small changes to simple acoustic stimuli (pure tones) leads to gradual changes in people’s perception of these stimuli.
   - > when VOT goes above 35ms, perception from /da/ changes to /ta/.
2. Discontinuous discrimination performance – Two stimuli with VOTs on same side of phonetic boundary (25ms) are judged to be same (= perceptual constancy), whereas two stimuli on different sides of phonetic boundary are judged to be different.
   - > If we did not have perceptual constancy we would perceive different sounds every time we changed VOT.

Question 21

Information provided by face/audiovisual speech perception (perceiving phonemes)

Answer 21

Speech perception is multimodal, meaning that our perception of speech can be influenced by information from a number of different senses.

Question 22

McGurk Effect

Answer 22

Effect illustrating that although auditory information is major source of information for speech perception, visual information can also exert strong influence on what we hear (= audiovisual speech perception).

Question 23

When someone perceives someone talking i.e. their face what area is also activated

Answer 23

FFA

Question 24

Information from our knowledge of language

Answer 24

Research showed that it is easier to perceive phonemes that appear in meaningful context.

Question 25

Bottom up processing of speech perception

Answer 25

nature of acoustic signal

Question 26

Top down processing of speech perception

Answer 26

context that produces expectations in listener

Question 27

Phonemic restoration effect

Answer 27

effect in which sounds missing from speech can be restored by the brain and appear to be heard
- more likely to work for higher frequencies -> the mask must have a similar frequency for us to fill in the blank correctly

Question 28

What does the phonemic restoration effect show?

Answer 28

shows that speech perception can be determined by:

1 bottom up processing
2 top down processing

Question 29

Discuss perceiving words in sentences

Answer 29

Words are more intelligible when heard in context of grammatical sentence than when presented as items in list of unconnected words

Question 30

Speech segmentation

Answer 30

Perception of individual words in a conversation

Question 31

What does speech segmentation prove?

Answer 31

our perception of words is not only based on energy stimulating receptors, but also on knowledge of meaning of words

Question 32

Transitional probabilities

Answer 32

Chances that one sound will follow another sound

Question 33

Statistical learning

- when acquired?

Answer 33

Process of learning about transitional probabilities and about other characteristics of language
- acquired as soon as 8 months

Question 34

Indexical characteristics

Answer 34

carry information about speakers such as age, gender, place of origin, emotional state and whether they are being sarcastic or serious

• listeners take in 2 levels of information about words: its meaning and the characteristics of speaker’s voice

Question 35

Aphasia

Answer 35

language problems due to damage

Question 36

Broca’s aphasia

Answer 36

Condition in which people have difficulty speaking but are capable of comprehending what others are saying. It results from damage to Broca’s area in frontal lobe.

Question 37

Wernicke’s area

Answer 37

Condition in which people can speak fluently but what they say is disorganized and not meaningful, plus they have great difficulty understanding what other people are saying. Results from damage to Wernicke’s area in temporal lobe -> what pathway for recognizing speech.

Question 38

Word deafness

Answer 38

Extreme case of Wernicke’s aphasia in which people cannot recognize words even if they can still hear pure tones.

Question 39

Voice area

Answer 39

superior temporal sulcus, activates more for human voices than other sounds

Question 40

Voice cells

Answer 40

temporal lobe, respond more to “voice” sounds than “non-voice” sounds

Question 41

Ventral (what) pathway

Answer 41

temporal lobe, recognizing speech

Question 42

Dorsal (where) pathway

Answer 42

parietal love, responsible for linking acoustic signal to movements used to produce speech

Question 43

Are the sound waves more like yanny or laural?

Answer 43

laurel

Question 44

Do younger ears hear laurel or yanny more often?

Answer 44

yanny

Question 45

The motor theory of speech perception

Answer 45

the hypothesis that people perceive spoken words by identifying the vocal tract gestures with which they are pronounced rather than by identifying the sound patterns that speech generates (activity of motor cortex can influence speech perception) – however theory is highly criticized