Speech Perception

Question 1

acoustic signal/acoustic stimulus

Answer 1

patterns of pressure changes in the air produced by the position/movement of structures within the vocal apparatus

Question 2

role of vocal cords and vocal tract

Answer 2

the acoustic signal for most speech sounds is created by air that is pushed up from the lungs past the vocal cords and into the vocal tract (the airway above the larynx used for the production of speech - it includes the oral and nasal tracts). The produced sound depends on the shape of the vocal tract as air escaping from the lungs is pushed through it.

Question 3

articulators

Answer 3

structures such as the tongue, lips, teeth, jaw and soft palate, which alter the shape of the vocal tract by moving

Question 4

How are vowels produced?

Answer 4

by vibration of the vocal cords; the specific sounds of each vowel are created by changing the overall shape of the vocal tract. This change of shape changes the resonant frequency of the vocal tract and produces peaks of pressure at a number of different frequencies. The frequencies at which these peaks occur are called formants

Question 5

formants

Answer 5

each vowel has a particular series of formants. The first formant has the lowest frequency, the second formant is the next highest.

Question 6

How are consonants produced?

Answer 6

by constriction (narrowing) of the vocal tract. For example, to produce a /d/, one places their tongue against the ridge above the upper teeth and release a slight rush of air as they move the tongue away from the alveolar ridge

Question 7

Manner of articulation

Answer 7

how the articulators interact when making a speech sound, e.g. /b/ is created by blocking the airflow and releasing it quickly

Question 8

Place of articulation

Answer 8

the locations of the articulation - lips, alveolar bridge or the soft palate (e.g., when saying /g/, /d/, and /b/, the place of articulation moves from back to the front of the mouth

Question 9

voicing

Answer 9

whether or not the vocal cords are vibrating (/b/, /m/, /z/, etc.) or not (/p/,/s/, etc.)

Question 10

Sound spectrogram

Answer 10

a visual representation of a sound’s spectrum of frequencies as it varies with time. It shoes which frequencies are in a sound at which moment of time

Question 11

Formant transitions

Answer 11

rapid shifts in frequency preceding or following formants

Question 12

phoneme

Answer 12

the shortest segment of speech that, if changed, would change the meaning of a word. Phonemes do not refer to letters but to speech sounds that determine the meaning of speech

Question 13

variability problem

Answer 13

a particular phoneme can be associated with a number of different acoustic signals

Question 14

Coarticulation

Answer 14

the overlap between the articulation of neighboring phonemes, e.g., bats and boots. Since the articulators are constantly moving while we talk, the shape of the vocal tract associated with a particular phoneme is influenced by the sounds that precede and follow that phoneme

Question 15

between-speaker differences

Answer 15

variations in how different people pronounce words. Variations between speakers such as pitch, speed and accent result in a particular phoneme having different acoustic signals for different speakers

Question 16

within-speaker differences

Answer 16

variations in how an individual pronounces words. For example, talking to a friend versus talking to a teacher might lead to differences in pronounciation

Question 17

motor theory of speech perception

Answer 17

based on the fact that motor commands have a 1:1 relationship to phonemes. It states that hearing a sound triggers motor processes in the listener associated with producing the sound. Has been disproven

Question 18

categorical perception

Answer 18

stimuli that exist along a continuum are perceived as divided into discrete categories

Question 19

voice onset time (VOT)

Answer 19

the time delay between when a sound begins and when the vocal cords begin vibrating

Question 20

phonetic boundary

Answer 20

the VOT at which perception changes from one category to another. The fact that all stimuli on the same side of the phonetic boundary are perceived as the same category is an example of perceptual constancy

Question 21

phonemic restoration effect

Answer 21

sounds missing from speech can be restored by the brain and actually be perceived
-> more likely to happen for longer words
-> influenced by meaning of words following the missing phoneme

Question 22

speech segmentation

Answer 22

the perception of individual words in a conversation. The acoustic signal for spoken sentences is continuous, but we perceive breaks between words. The meaning of words help us segment speech by knowing which word can fit in which context

Question 23

transitional probability

Answer 23

the chance that one sound will follow another sound. Every language has different transitional probabilities, which are learned along with learning to understand words and sentences

Question 24

why is speech perception multimodal=

Answer 24

it can be influenced by information from other senses such as vision and touch

Question 25

McGurk effect

Answer 25

seeing a person’s lips make movements for one sound influences how the actual sound that arrives to the ears is perceived

Question 26

aphasia

Answer 26

a language disorder caused by damage in a specific area of the brain that controls language expression and comprehension

Question 27

Broca’s aphasia

Answer 27

caused by damage to Broca’s area in the frontal lobe. It causes patients to have slow, labored, ungrammatical speech. They also have difficulty understanding some types of sentences (e.g., sentences that contain connecting words such as “by”).

Question 28

Wernicke’s aphasia

Answer 28

caused by damage to Wernicke’s area in the temporal lobe. It causes patients to produce fluent & grammatically correct, but meaningless speech. They are also unable to understand speech and writing

Question 29

word deafness

Answer 29

inability to recognize words, even though the ability to hear pure tones remains intact. It occurs in the most extreme form of Wernicke’s aphasia

Question 30

Dual-stream model of speech perception

Answer 30

a model that identifies 2 streams for speech perception

Question 31

ventral stream

Answer 31

supports speech comprehension. sends signals from the anterior auditory area to the frontal cortex.

Question 32

dorsal stream

Answer 32

involved in linking the acoustic signal to the movements used to produce speech. Sends signals from the posterior auditory area to the parietal lobe and motor areas.

Question 33

voice cells

Answer 33

neurons in monkeys’ what hearing pathway in the temporal lobe that respond strongly to recordings of monkey calls than to calls of other animals

Question 34

Why has the Motor Theory of Speech Perception been disproven?

Answer 34

Study: TMS of motor areas associated with making specific sounds can aid in perception of these sounds.
-> Stimulation of lip area resulted in faster responding to the phenomes /b/ and /p/
-> Stimulation of the tongue area resulted in faster responding to the phonemes /d/ and /t/
! Does not explain how people with brain damage that disables their speech motor system can still perceive speech
! Does not explain how infants can understand speech before they have learned to speak.

Question 35

Study: VOT

Answer 35

Listeners are asked to indicate what sound they heaer when the researchers vary the VOT between 0 and 80ms
-> Listeners only reported hearing /da/ or /ta/, despite the fact that a large number of different stimuli (with different VOTs) were presented
-> From 0 to about 35ms, listeners hear /da/. From 35ms and above, their perception changes abruptly to /ta/.

Question 36

Meaningful context study

Answer 36

Listeners were presented with a series of short words or nonwords. They were asked to press a key as rapidly as possible whenever they heard a sound that began with the phenome /b/. On average, it took participants 632ms to respond to the nonwords and 580ms to respond to the real words.

Question 37

Study phenomic restoration effect

Answer 37

Participants listen to a recording of the sentence “The state governors met with their respective legislatures convening in the capital city.”, where the first /s/ in “legislatures” was replaced with the sound of a cough
-> Participants were asked where in the sentence the cough occurred
-> None of the participants identified the correct position of the cough. None noticed that the /s/ in “legislatures” was missing.

Question 38

Study McGurk Effect

Answer 38

fMRI activity was recorded in observers who watched a silent videotape of a person making mouth movements for saying numbers.
-> Watching the lips move activated an area in the auditory cortex that was previously shown in another experiment to be activated when people are perceiving speech.

Question 39

Study Dual-Stream model of speech perception

Answer 39

fMRI response was measured in 2 conditions: telling a story (production condition) and listening to the story (comprehension condition)
-> Several brain areas responded in both conditions => this could be due to shared mechanisms in speech production and comprehension, but could also be explained with different types of processing within these 2 regions in the different conditions
-> However, the neural responses to production and comprehension were coupled (followed the same time course), suggesting shared processing mechanisms

Question 40

Speech Perception and Face Perception Study

Answer 40

Listeners who listened to sentences by familar speakers or unfamiliar speakers had their brain activity measured with fMRI
-> In both conditions, the superior temporal sulcus (associated with speech perception) was activated
-> When familiar speakers were listened to, the fusiform face area was also activated

Question 41

What happens when speech sounds become part of a language?

Answer 41

Anterior + Ventral regions, mostly in left superior temporal cortex, but also in posterior superior temporal cortex