Download PowerPoint presentation

SPHSC 462
HEARING
DEVELOPMENT
Overview
Review of Hearing Science
Introduction
Overview of course and
requirements
Lecture/discussion; lecture notes on website
http://faculty.washington.edu/lawerner/sphsc462/
 No text; chapter and other readings on website
 Requirements: two take-home exams (40% grade each)
and discussion questions/in-class discussion of articles
(20% grade).

Exams




Take-home
Essay
Open book
Must work alone; penalty for breaking this
rule is failing grade
Article discussion



Articles every week starting Oct 15.
I will provide some questions to guide you through the
articles.
You will submit one question about things you didn’t
understand, one question that you think it would be
interesting to discuss and answer the question, “How is
this article relevant to me? by 5:30 am on discussion day.
Drop boxes

Your discussion questions:


https://catalysttools.washington.edu/collectit/drop
box/lawerner/7177
Take-home exams

https://catalysttools.washington.edu/collectit/drop
box/lawerner/7143
Review of Hearing
Science
Hearing in a nutshell
Wow! Psychophysics
is interesting!
FREQUENCY
TIME
What are the characteristics of sound
represented in the auditory nerve response?



Intensity
Frequency
Temporal characteristics (changes in
intensity or frequency over time)
How does the ear come to represent these
characteristics of sound?



Conduction
Transduction
Traveling wave and Active Mechanism
Conduction
Frequency (Hz)
Frequency (Hz)
Frequency (Hz)
Frequency (Hz)
Transduction: changing acoustic
energy to electrochemical energy
A
B
C
E
D
F
QuickTime™ and a
Animation decompressor
are needed to see this picture.
Where does the code for intensity
come from?
QuickTime™ and a
Animation decompressor
are needed to see this picture.
Low level
QuickTime™ and a
Animation decompressor
are needed to see this picture.
High level
Combined firing rate
of auditory nerve
fibers with the same
best frequency
Where does the code for frequency
come from?
QuickTime™ and a
Sorenson Video decompressor
are needed to see this picture.
Hair cell potential
0
Time
Time
Spikes
Pressure
Coding of the time waveform of
sound: Tone
Time
Hair cell potential
0
Time
Time
Spikes
Pressure
Coding of the time waveform of
sound: Complex waveform
Time
Hair cell potential
0
Time
Time
Spikes
Pressure
Coding of the time waveform of
sound: High frequency tone
Time
Hair cell potential
0
Time
Time
Spikes
Pressure
Coding of the time waveform of
sound: High frequency complex
Time
Where does the code for frequency
come from?
For low frequencies, a code for
frequency is carried in the timing of
auditory nerve action.
Where does the code for temporal
characteristics come from?
QuickTime™ and a
Sorenson Video decompressor
are needed to see this picture.
Pressure
Pressure
Coding of the time waveform of
sound: Temporal characteristics
0
0
Time
Spikes
Spikes
Time
Time
Time
Traveling wave and
active mechanism
The other code for frequency
Basilar membrane motion
Base
Apex
Traveling wave
QuickTime™ and a
Sorenson Video decompressor
are needed to see this picture.
QuickTime™ and a
Sorenson Video decompressor
are needed to see this picture.
Traveling wave
QuickTime™ and a
Animation decompressor
are needed to see this picture.
The active mechanism
How are these three characteristics of sound
represented in the auditory nerve response?



Intensity
Frequency
Temporal
characteristics



Combined firing rate of
auditory nerve fibers
with the same CF
Place code and
temporal code
Phase-locking, but
with limitations
So the message in the auditory
nerve is sort of like a spectrogram
FREQUENCY = POSITION
OF AN FIBER ALONG
BASILAR MEMBRANE
TIME
Hearing in a nutshell
Wow! Psychophysics
is interesting!
FREQUENCY
TIME
Sound source segregation
FREQUENCY
TIME
Cues that could be used to
segregate components into sources







Spectral separation
Spectral profile
Harmonicity
Spatial separation
Temporal separation
Temporal onsets and offsets
Temporal modulations
Hearing in a nutshell and sound
source segregation
Wow! Psychophysics
is interesting!
FREQUENCY
TIME
Acoustic cues used in localization
Interaural intensity differences
Interaural time differences
Spectral shape
cues
For next time

Read p. 1-14 of “Human auditory
development” chapter, Intro and Frequency
representation