Sensation and Perception (II)3270
Speech
Keywords on hearing (introduction)
auditory canal, ear drum, ossicles, oval window, cochlea, helicotrema, basilar membrane, tectorial membrane, hair cells, kinocilium, stereocilia,
amplification (by ossicles & area difference between ear drum and oval window), travelling wave, resonance, tonotopic coding, cochleotopic coding, transduction
auditory thresholds, effect of age, different animals, fundamental, harmonics, timbre, pitch/frequency, loudness/amplitude, pure tone, equal loudness, masking
place theory, periodicity theory, duplicity theory, missing fundamental, goldfish has no basilar membrane - can distinguish freqs, phase-locking, diplacusis,
PHONEMES
“sounds that create meaning”
47 in English
VOICING PLACE OF MANNER OFARTICULATION ARTICULATION
voiced alveloar ridge stop unvoiced labiodental fricative
etc… nasaletc…
http://nationalstrategies.standards.dcsf.gov.uk/node/85357
time
Formant 3
Formant 2
Formant 1
Formant transitions
Formants
SEGMENTATION PROBLEM
Segmentation problem
Where one sound is influenced by what sound came before or after because of CO-ARTICULATION
Same sounds, different spectrographs...
VARIABILITY PROBLEM
IS SPEECH SPECIAL?
1. MOTOR THEORY OF SPEECH
-- mirror neurones?
http://www.teachersdomain.org/asset/hew06_vid_mirrorneurons/
IS SPEECH SPECIAL?
2. CATEGORICAL PERCEPTION
Voice Onset Time (VOT)
ShortVOT
LongVOT
“SAME”“DIFFERENT”
IS SPEECH SPECIAL?
3. SPEECH PERCEPTION IS MULTIMODAL
McGurk Effect
SOUND
VISION
Video demos
1. McGurk effect
video=gasound = bacombo= da
2. Vision helps degraded sound
IS SPEECH SPECIAL?
4. Are there INVARIANTS for phonemes?
-- practical importance-- some hints-- varied by neighbouring sound-- different conditions eg. speed of speech-- different speakers-- but TOP DOWN INFLUENCES
TOP-DOWN INFLUENCES
1. Segmentation influenced by meaning
Anna Mary Candy Lights Since Imp PulpLay Things.
I scream, you scream, we all scream for ice cream!!
TOP DOWN INFLUENCES
1. Segmentation influenced by meaning2. Semantics (meaning) and syntax (grammar)
both influence your ability to shadow (repeat what you have heard) a text.p
erce
nt
corr
ect 89%
79%
56%
normal s
entences
anomalous sentences
ungrammatic
al sentences
TOP DOWN INFLUENCES
1. Segmentation influenced by meaning2. Semantics (meaning) and syntax (grammar) both
influence your ability to shadow (repeat what you have heard) a text.
3. Phonemic restoration.
Time to meet with their respective legi laturess *
cough
time to aves the countryw the flag
Pink noise demo: http://www.youtube.com/watch?v=k74KCfSDCn8
Legislatures: http://www.youtube.com/watch?v=UlJs24j3i8E&feature=related
SUMMARY “Is speech special?”
1. Motor theory of speech2. Categorical perception3. Multimodal aspects4. Invariants
Top down influences(i) Segmentation influenced by meaning(ii) Shadowing influenced by meaning(iii) Phonemic restoration
PHYSIOLOGY OF SPEECH PERCEPTION
Might there be phoneme detectors in the brain?
Voice onset time (ms)0 20 40 60 80
Per
cen
tag
e h
eard
as
“da”
100%
50%
0%
Per
cen
tag
e h
eard
as
“ba”0%
50%
100%
/da/
/ba/
ADAPT TO /ba/
/ba/ /ba/
/ba/
/ba/
/ba/
/ba/
/ba/
/ba/
/ba/
/ba/
/ba/
/ba/
After adapting to /ba/……
Voice onset time (ms)0 20 40 60 80
Per
cen
tag
e h
eard
as
“da”
100%
50%
0%
Per
cen
tag
e h
eard
as
“ba”0%
50%
100%
/da/
/ba/
As if that wasn’t cool enough…..
What happens after adapting to a McGurk effect?
Sound = /ba/
Vision = /ga/
Perception = /da/
acoustic
perception
After adapting to McGurk
Voice onset time (ms)0 20 40 60 80
Per
cen
tag
e h
eard
as
“da”
100%
50%
0%
Per
cen
tag
e h
eard
as
“ba”0%
50%
100%
/da/
/ba/
If /ba/ (acoustic) adapts
If /da/ (perception) adapts
??
It is the ACOUSTIC signal that adapts
Voice onset time (ms)0 20 40 60 80
Per
cen
tag
e h
eard
as
“da”
100%
50%
0%
Per
cen
tag
e h
eard
as
“ba”0%
50%
100%
/da/
/ba/
Acoustic adapts!!!
Broca’s aphasia http://www.youtube.com/watch?v=f2IiMEbMnPM
Wernicke’s aphasia http://www.youtube.com/watch?v=B-LD5jzXpLE
Cells in cortex show:
• Phoneme information carried in a population code
• Special features in auditory cortex (eg, frequency sweeps) compatible with phonemic features
Background resting activity -- note more activity in frontal regions
Green = averageblue = lessred = more
Looking around
Frontal eye fields
Visual cortex
Listening to words
WERNICKE’S AREA
Auditory cortex
Counting out loud
Supplementarymotor area
BROCA’S AREA(speech production)
WERNICKE’S AREA(speech understanding)
Internal speech -- counting in your head
?????
Internal speech -- counting in your head
Frontal regions
NOTBroca or Wernicke’sareas !!!!
olfactory binding protein, olfactory receptors cells continuously regenerate (about every 60 days), cilia (on olfactory receptor cells), glomerulus (contact zones between receptor cells and mitral cells:plural glomeruli), convergence (1,000:1), mitral cell, olfactory tubercle of cortex (part of paleocortex), medial dorsal nucleus of thalamus , orbitofrontal cortex, olfactory neocortex
paleocortex associated with limbic system, limbic system associated with emotions (electrical stimulation causes sham rage), limbic system associated with memories (H.M. had lesions here and lost the ability to memorize things), some hot spots in olfactory tubercle and on olfactory mucosa
KEYWORDS -- SMELL I
odour quality, no primaries identified in olfactory system, poor tuning of receptors (to chemicals or chemical types) (sharpened by lateral inhibition, inhibitory interneurones, granule cells), Henning smell prism, stereochemical theories based on lock and key partially successful, BUT no receptor sites identified, similar shaped molecules can be associated with different smell perceptions
cells broadly tuned (responding to many different chemicals associated with many different smells)
codingintensity= firing rate/recruitment, quality = distributed pattern code, problems in identifying many smells at once, binding problem
KEYWORDS -- SMELL II
odour thresholds, olfactorium; unique technical problems!, humans very sensitive (eg. mercaton can be detected at 1 part per 50,000,000,000), affected by gender; can be affected by menstrual cycle, affected by age
adaptation, thresholds raised (by exposure), masking (by other chemicals), some cross effects: eg. adapting to orange affects smell of lemons
identification, can identify gender from shirt, prefer own odours, odour memories long lasting; associated with emotions (via limbic system) "designed not to forget”, pheromones, releasers (immediate effect), eg. bitch on heat, territorial markers, humans?, McClintock effect (synchronized menstrual cycles), primers (longer term) eg. mice need males around for proper oestrus cycles
KEYWORDS -- SMELL III
PATHWAYS olfactory receptor cells to mitral cells in olfactory bulb to olfactory tubercle in paleocortex THEN
1 to medial dorsal thalamus to olfactory cortex
(ORBITOFRONTAL CORTEX) 2 to limbic system 3 brain stem pathways associated with pheromones
ALSO
inhibitory pathway (via inhibitory interneurone: granule cells) from one olfactory bulb to the other to do with detecting the DIRECTION from which a smell originates
KEYWORDS -- SMELL IV