Speech Perception

Question 1

Speech Production

Answer 1

• cavities/articulators: speech sounds
• vocal cords: voicing
• lungs: power source for speech

Question 2

Source-filter Theory of Speech Production

Answer 2

Source-filter theory: the unshaped source material (sound from vocal folds) is shaped by the articulators (filter), giving rise to a sound with characteristics of both source and filter

vocal tone (from vocal cords; source) + resonatory cavitives/articulators (filter) = speech (output)

Question 3

Articulation

Answer 3

Articulation: the approach or contact of two speech organs
- eg: tip of tongue + upper teeth for “th” in thin

Question 4

Acoustics

Answer 4

Acoustics: the study of the physical properties of sounds, eg:
- loudness
- pitch

Question 5

Frequency

Answer 5

Frequency: (acoustic property) described in terms of cycles per second; measured in Hertz (Hz)

Question 6

Pitch

Answer 6

Pitch: auditory property related to frequency

Question 7

Formants

Answer 7

Formants: overtone pitches that get emphasized by vocal tracts in a particular shape, and gives vowels their characteristic sounds
- fundamental frequency (F0) — lowest formant
- first formant (F1)
- second formant (F2)

Question 8

Sound Variability

Answer 8

Sound variability: no one-to-one correspondence between acoustic signal and sound perceived

Sound varies:
1) Across speakers
2) Within speakers

Question 9

Sound Variability
1) Across Speakers

Answer 9

Sound variability across speakers:
- different speakers have different mouth sizes, shapes and vocal tracts
- individuals differ in the range of their fundamental frequency (F0)

Question 10

Sound Variability
2) Within Speakers

Answer 10

Sound variability within speakers:
Articulatory Speed: articulators are not always in the ideal position; production therefore is not “ideal”

Coarticulation Effects: variation in the pronunciation of a phoneme caused by the articulatory properties of neighboring sounds
- eg: cat vs can

Parallel Transmission: information for segments overlap
- however, it’s difficult to know when the sound begins and ends in the speech spectrum

Question 11

Sound Variability
Other Sources

Answer 11

Other sources of sound variability:
- foreign accents/variants
- noise

Question 12

Perceptual Invariance

Answer 12

Perceptual Invariance (“lack of invariance”): the ability to perceive sounds that have highly variable acoustic manifestations as instances of the same sound category

Question 13

Speech Perception

Answer 13

Interpreting sounds into categories
- our minds impose a lot of structure on speech sounds (as a result of learning)
- we mentally group clusters of similar sounds (allophones/variants) into phonemes
- mental categories play an important role; these categories warp perception

Question 14

VOT

Answer 14

Voice Onset Time (VOT): the time difference between the release of the stop and the onset of vibration

Question 15

Speech Perception Tasks

Answer 15

Tasks for Speech Perception
1) Forced Choice Identification Task
2) ABX Discrimination Task

Question 16

Speech Perception Tasks
1) Forced Choice Identification Task

Answer 16

Forced Choice Identification Task
- asks the participants to label the stimuli
- eg: “what is this sound?” (di // ti ?)

Question 17

Speech Perception Tasks
2) ABX Discrimination Task

Answer 17

ABX Discrimination Task
- present two different stimuli (A and B), one of which is a control sample, the other a modified sample
- eg: “di” and “ti”

• present a third stimulus (X)
• participants must decide whether stimulus X is more representative of A or B

Question 18

Categorical Perception

Answer 18

Categorical Perception: perception of continous changes in a stimulus as having a sharp break between discrete categories
- despite the variability, you interpret the gradience of sounds into categories (with sharp boundaries)

Question 19

Speech Perception Cues
(1) Visual Cues

Answer 19

McGurk effect:
- an audio-visual illusion that illustrates how perceivers merge info for speech sounds across the senses
- eg: VIDEO “ga” + RECORDING “ba” → PERCEPTION is “da”
- we integrate information from visual cues

visual cues are a bottom-up process :
- interpretation
- ↑
- sensory input

Question 20

Speech Perception Cues
(2) Contextual Effects:
Ganong Effect

Answer 20

Ganong effect
- the impact of lexical knowledge on auditory perception of words when stimuli are acoustically ambiguous
- the context where the sound is affects speech perception
- the perception of phonetically-ambiguous sounds can be biased by the likelihood of the resulting word-form being a lexical item or not

context cues are a top-down process
- knowledge
- ↓
- interpretation

Question 21

Speech Perception Cues
(2) Contextual Effects:
Phoneme Restoration Effect

Answer 21

Phoneme Restoration Effect: under certain conditions, sounds that are actually missing from a speech signal can be restored by the brain, and may appear to be heard
- “hallucinating effects” on sounds
- non-speech sound replaces a speech sound
- eg : /s/ in “legi[^]lature”

context cues are a top-down process
- knowledge
- ↓
- interpretation