2.5 - Speech Perception Flashcards
Speech Stimulus
Articulary Gestures (physical movement of muscles to create sound)
Vocal Chords
Muscles where speech production occurs (Vibrating = voice, non-vibrating = voiceless)
Speech Spectrogram
graph of speech sounds by Frequency (Hz) per second. Contains formants and formant transitions
Phonetic Segments overlap
Formant
On Speech Spectrogram: Energy clusters in complex sounds
Formant Transition
Where it slops in or out of a formant, crucial in specific sounds (ex: Bah vs Pah)
Coarticulation
Phonemes sounds can change depending on what precedes or follows it (Same sound, different speech spectrograph based off of before and after)
Facts about speech production
specific words are not produced the same way for specific individuals, no single constant pronunciation exists for phonemes
Production of Vowels
Tongue Only
Production of Consonants
Place of articulation (whats touching) and manner of articulation (how it is touching)
Parts of mouth involved in production of consonants
Lips, Teeth, Tongue, Alveolar Ridge, Palate, Velum, Glottal
Voicing
(voice vs voiceless) the delay between passage of air and when vocal cords vibrate (onset is around 10ms) and is the difference between hearing Pah vs Bah
VOT
Voicing onset time: 10-20mS (where it changes)
Phonetic boundary
where voicing onset time occurs (changes sound)
Special Mechanism Theory of Speech Perception
(Inborn belief) Speech depends on specific mechanisms (different than other acoustic information)
Example: Motor theory
Motor Theory of Speech Perception
(special mechanism camp)
Speech perception is the result of activation of motor program required to produce a phoneme
IE: to understand speech you need to know the articulary gestures (If you haven’t heard a sound, you can’t produce it)
General Mechanism Theory of Speech Perception
(Learnt belief) no special speech module exists, produced same as non-speech sounds
Not a theory but rather same theories as regular sound perception theories (cues for sound localization and sound distinction)
Evidence of General Mechanism Camp
Variation in the same language but can still understand each other
Segmentation
Breaking down quality (Fundamental and harmonics) of words (this is done before 1 years old) afterwards then word recognition processes develop and takes over
Categorical Perception
Suggests that we prefer discrete units as opposed to gradiations in acoustic properties
Needs: High discriminability (sharp identification of speech sounds on a continuum) Low discriminability (within phonetic categoies)
evidence:
EX: BAH vs PAH
You can identify when phonetic boundary but within the category no discrimination
at the VOT there is low discrimination
evidence against:
animals without speech have categorical perception (example: chinchillas)
non-speech sounds produce categorical perception
How to measure:
- oddity method
in the end:
evidence against because its too contradicting
Oddity method
3 stimulus, 2 are the same. pick out which one is the odd one out
Linguistic Features Detector
specific detection mechanism for linguistic features.
adaptation of a heard sounds fatigues said detector for when we hear another sound
Duplex Detection
Same sound can be heard as speech or not speech
- categorical perception only occurs when speech is perceived, then speech is special
experiment:
- present pieces of a sound (base in one ear and transition in the other)
- people who haven’t heard the speech sound will perceive it as pieces
- people who have heard the speech sound will perceive it as a whole
proves speech is special
Laterialization of Language
left hemisphere of brain is presumed to process speech
there is a right ear advantage in people that are right handers
experiment:
- dichotic presentation of verbal stimuli
0 if it produces a left hemisphere advantage (right ear) then speech is special
speech is special
however:
- doesn’t work for left handers
advantage is not obtained fo vowels
localization of language
strongest evidence that speech is special
there are special areas of the brain involved in speech in the left hemisphere (brocas area and wernickes area)
