Human hearing
Physical Characteristics
Human hearing
Limits, the human ear, and issues
of perception
Frequency range: 20 Hz … 20 kHz
Factor of 1000
Intensity range: 10-12 to 1 W/m2
Factor of 1012
Filtering of information
Sylke Boyd, Univ. of Minnesota
Physical characteristics
Psychophysics:
objective and quantitative study of the relation
of physical stimuli and sensory perceptions
Middle Ear:
Transformation
into mechanical
and then
electrical signals
Pressure fluctuations
Processing:
sorting, selection,
recognition
Graphics: Rossing, Moore & Wheeler, The Science of Sound, 3rd Ed.
Structure
of the
human
ear
Phys1061, S.Boyd
Important parts of the Cochlea
Oval window
Scala vestibuli (filled
with fluid)
Scala timpani
Round window
Basiliar membrane
Organ of Corti
Auditory nerve
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Human hearing
Mechanism of signal transport
Lever action of ossicles
Small displacement over large area becomes
large displacement over small area
Hall, Musical Acoustics, 3rd Ed.
Just noticeable differences
At which frequency difference do two
tones sound different to us?
200/201 Hz
200/202 Hz
200/203 Hz
2000/2002 Hz
2000/2003 Hz
2000/2004 Hz
2000/2006 Hz
2000/2008 Hz
How are sounds resolved?
Simultaneous sounds
At which difference in frequency can we
hear two distinct sounds?
1000 Hz combined with …
700 Hz
800 Hz
900 Hz
990 Hz 1010 Hz
980 Hz
950 Hz
1100 Hz 1200 Hz 1300 Hz
1020 Hz
1050 Hz
How are sounds resolved?
Critical band: region on basilar membrane
for reception of a pure tone
If critical bands overlap, only a single tone
is heard
The (relative) critical band is larger at low
frequencies.
Phys1061, S.Boyd
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