Development of the Auditory Response

Question 1

Fetal Development Basics

Answer 1

REM is important
Can get NIHL
Need auditory stimulation
connections to the temporal lobe
Earliest auditory evoked response

Question 2

Development of Cochlea

Answer 2

Cochlea formed fully by midgestation–earliest cochlea inner ear to brain stem established ~16 weeks GA

28-30 weeks GA connections to temporal lobe, need auditory stimulation from 28 weeks on

Low frequency HC tuned first—babies in utero have hearing muted by skin, fluid, tissues–protected from HF, short waveforms die out very quickly

Question 3

Babies and HF vs LF

Answer 3

psychoacoustically better able to encode HF but better respond to LF

localize better with HF than LF

Question 4

Adults vs Babies

Answer 4

In quiet: adults responded much better than infants—adults responded better to LF and babies responded better to HF

development of auditory system that progresses as cognitive psychoacoustics advance

Question 5

Why might Infants hear better in HF

Answer 5

infants have smaller ear canals
ME impedance favors HF
adults lose HF sensitivity as age
frequency specific differences in localization process

Question 6

Smaller Ear canal size

Answer 6

Decrease size of tube, but sound stays the same so sound will become louder and will have HF sound because bouncing off walls creating shorter wavelengths

Question 7

Middle Ear Impedance

Answer 7

Not completely ossified, have gelatinous mesenchyme in ME space – mass-dominated rather than stiffness dominated (newborns under 6months) more mass to ossicles in ME system than in older kids—

thicker system impede/keep back sound from getting through
1. LF causes system to vibrate more BUT actually dampens LF and HF travel through more readily

Question 8

Birth-4 months

Answer 8

kid can raise up from ground…enables head turning to enable VRA

might soothe to music

Question 9

Birth-4 months

Answer 9

Not a lot of motor planning: Moro reflex (startle reflex) around 65dB

reflexive auditory responses (blinking, widening eyes)

highly variable resonses

by 3-4 months may demonstrate slow head turn toward sound but not guaranteed

Question 10

4-7 Months

Answer 10

More consistent head turn to sound–7 months can turn to either side well
localization only on the lateral plane

Question 11

7-9 months

Answer 11

precise localization occurs (quick, sharp head turn), but may not have localization ability above plane of head

can start VRA
babbling, peak a boo, bye bye wave, gestures and vocalization

Question 12

9-13 Months

Answer 12

talk a lot, different expressions, make different sounds
can follow simple commands–may be interested in sound, connect with their auditory environment, doing it socially and imitating sounds

by 13th month can localize in all directions, considered to have reached full maturation of auditory development

Question 13

Auditory Skills Hierarchy

Answer 13

Detection/Awareness & attention (threshold)
Discrimination (differentiate between mom & dad, person talking vs dog barking)
Recognition
Comprehension (words & phrases with cues–words & phrases auditory only — sentences –conversation)

Question 14

Speech Perception

Answer 14

When we want to know how well they are using the detection—we are testing speech perception: functional hearing capacity

goes beyond threshold detection, determine auditory capacity/functional hearing

Question 15

Speech Perception Tests

Answer 15

auditory skill vs environmental–different tests give us different information

can test kid’s ability to perceive speech at all levels