Speech and Hearing Sciences Final

Linguistic Level of the Speech Chain

Where speech perception happens, (in the brain), speaker forms a thought

Physiological Level of the Speech Chain (Speaker): 

thought is communicated to the listener

Physiological Level of the Speech Chain (Listener):

Sound waves go through listeners ear and hit sensory nerves which travel to the brain (linguistic level)

Acoustic Level of the Speech Chain

Sound waves get sent to listeners ears but also feedback is sent back to speakers ears

Speech Perception in Speech Chain

The perception of whats being said occurs in the brain, this is where we put understanding behind the acoustic level of speech sounds.

Perception implies

meaning comprehension

Who has speech perception

both listener and speaker

What does the outer ear contain

Pinna and External Auditory Canal

Pinna or Auricle 

funnels sound to the ear canal and helps localize sound 

External Auditory Canal (Meatus)

leads to tympanic membrane (ear drum/middle ear)

What does the middle ear contain 

Air filled cavity, Tympanic membrane, ossicular chain, eustachian tube

Tympanic Membrane

Thin, tough, elastic, cone shaped membrane

Ossicular Chain

3 small bones: Malleus, Incus and stapes

Malleus

Hammer

incus

anvil

stapes

stirrup

Eustachian Tube

Connects middle ear to the nasopharynx

What does the eustachian tube do

equalizes pressure and aerates middle ear

what does the inner ear contain 

Three semicircular canals and cochlea

Semicircular Canals

help maintain balance

cochlea

primary inner ear structure of hearing, snail shaped coiled tunnel that is filled with fluid 

Vestibular system

the semicircular canals

Perilymph 

Fluid that fills the scala vestibule and scala tympani

Endolymph

fluid that fills scala media

Scala Media

middle of cochlea, contains the sensory organ of hearing (organ of corti)

Scala vestibuli

peripheral cavity of cochlea that communicates with the middle ear via the oval window

Scala tympani

peripheral cavity of cochlea that communicates with the middle ear via the round window

oval window

point where inner eat begins, allows communication between scala vestibuli and middle ear

moves in

round window 

allows communication between scala tympani and middle ear 

moves out

oval and round window

vibrations to the oval window cause pressure waves in the fluid filled tunnels of the cochlea, both allow movement of fluid in cochlea.

Basilar membrane

The floor of the cochlea, contains the organ of corti, membrane is thinner at base and thicker at apex

Thinner basilar membrane

higher frequency noise

Thicker basilar membrane

lower frequency noise

Acoustic nerve 

cranial nerves primary auditory area in temporal bone 

Step 1 of Physiology of Hearing

Sound waves are directed by the pinna into the ear canal (air conduction)

Step 2 of Physiology of Hearing

Waves strike the ear drum, cause it to vibrate

Step 3 of Physiology of Hearing

The ear drum is connected to the malleus which moves the ossicles back and forth

Step 4 of Physiology of Hearing

stapes move, pushes the oval window in an out 

Step 5 of Physiology of Hearing

The movement of the oval window makes waves within the fluid

Step 6 of Physiology of Hearing

Pressure of the wave cause the basilar membrane to vibrate, moving the cilia in OOC

Step 7 of Physiology of Hearing

Movement of hair generates nerve impulses

Step 8 of Physiology of Hearing

The nerve impulses are passed onto the 8th nerve, and transmitted to the auditory area of the brain

Organ or corti

Contain thousands of hair cells (cilia) that respond to sound

step 1 of Transformation of sound wave

Air disturbances converted to mechanical vibrations by ossicles in the middle ear

step 2 of Transformation of sound wave

mechanical vibrations transformed to fluid vibrations in the cochlea

step 3 of Transformation of sound wave

fluid vibration converted to electrochemical changes by the cilia and nerve endings in cochlea  

step 4 of Transformation of sound wave

electrochemical changes sent to brain as nerve impulses

speech perception

giving meaning to what is said, the ability to seek and recognize acoustic patterns, context and suprasegmentals used to help decode message

how are vowels distinguished

primarily by F1 and F2

first theory of vowels

we use pattern and not absolute formants for distinguishing vowels

second theory of vowels

we use point vowels to normalize formant frequencies to help with the identification of them

diphthongs

listener perceives rapid changes in formants

semivowels

frequency changes in F2 and sometimes F3, fast formant transitions contribute to their perception as consonant-like not diphthongs

What does F3 distinguish?

/r/ from /l/

nasals

formant transitions of vowels preceding nasal distinguishes nasals as a class

Due to antiformants or antiresonance

the upper formant is weakened

/m/

lowest frequency and shortest in duration

/n/

higher frequency and longer in duration 

/ŋ/

highest and most variable frequency and longest in duration

Stops

stop gap, release burst, VOT, formant transition

Bilabials

F2 increase from stop release to vowel

Alveolar 

F2 decreases from stop release to vowel, except for high-front vowels 

Velar

F2 decreases from stop release to vowel

fricatives

most distinguishable feature is aperiodic noise

Stridents (s,z,ʃ,ʒ)

have high frequency spectral peaks

nonstridents (f,v,h,θ,ð)

flat diffue spectra

/ə/

most confused; maybe because of small nonexistent resonating cavity 

Affricates

Characteristics of a stop with addition of fricatives listener listens for durational spectral cues in production

when can the fetus hear?

24 weeks gestation

How are speech components transmitted in utero

through amniotic fluids

at end of gestation baby can

preform speech relevant acoustic discrimination -=

how are fetus responses tested

using electrophysiological, neurochemcial, and mostly behavioral responses

Electrophysiological

microphones, auditory evoked potentials

neurochemical

measures fetal brain activity using cerebral glucose utilization (only animals)

Behavioral responses 

startle response, ultrasound, and heart rate changes 

What do infants prefer

Maternal voice, familiar story, musical sequences, speech sequences sung by mother, maternal language

Maternal vocalizations

gain and maintain infants attention and arousal state

prosodic elements

used to communicate maternal affect to infants (approval, happiness, anger, warning)

expanded intonation 

may facilitate infant identification of mother 

prosodic patterns could

contribute to the development of speech perception skills

Discrimination tasks

tested by changes in sucking rate

motor theories

listener refers to articulation to address variations in acoustic signal (speech is heard then listener accesses his or her own knowledge of how phonemes are articulated

auditory theories 

listener identifies acoustics patterns and matches them to learned and or stored acoustic phonetic features, listeners are sensitive to distinctive patterns speech wave, auditory features of phonemens are detected  

McGurk Effect 

When auditory and visual information both play a role in speech perception, we store visual as well as auditory memories of phonetic gestures 

Head turn procedure

A familiar sound is played for the baby, it is then recorded how long the baby turns its head to acknowledge the familiar sound

High Amplitude Sucking Method

Baby is given a pacifier and a sound is played over and over. At first the baby is interested and they suck their pacifier at a faster rate but over time they get bored, and the sucking slows. A new sound is then played which intrigues the baby again and the sucking increases again. Which shows the linguists that the baby can notice different sounds

Eye tracking & Preferential looking method

A sentece or word like “ball” is spoken and then two pictures are put infront of the child, and one picture is of a ball, and another one is something different. You watch the child’s head tracking to see if they can understand the meaning of the word that was said