MIT OpenCourseWare
http://ocw.mit.edu
9.35 Sensation And Perception
Spring 2009
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Hearing
Kimo Johnson
April 14, 2009
Tuesday, April 28, 2009
Psychoacoustics
•
•
•
•
Tuesday, April 28, 2009
Ask listeners how sounds are perceived
Pressure (dB) => loudness
Frequency (Hz) => pitch
Critical bandwidths
Relative amplitude of movement (µm)
b) Travelling waves
3
1600Hz
0
3
800Hz
0
3
400Hz
0
3
High frequencies
displace basilar
membrane in
base of cochlea.
"Unrolling" of cochlea
Basilar
membrane
Cochlear base
Direction of sound
movement
Low frequencies
displace basilar membrane
in apex of cochlea.
"Unrolled" cochlea
Cochlear apex
200Hz
0
3
100Hz
0
3
50Hz
0
3
25Hz
0
20
0
30
10
Distance from stapes (mm)
Figure by MIT OpenCourseWare.
Tuesday, April 28, 2009
Critical bands
•
Auditory filters
Amplitude (dB)
0
−10
−20
−30
−40
0
Tuesday, April 28, 2009
2
4
6
8
10 12 14
Frequency (kHz)
16
18
20
Critical bands
•
Width of “auditory filters”
-
Fletcher (1938)
Zwicker (1960,1990)
Moore, Glasberg
probe
intensity
noise
bw
Tuesday, April 28, 2009
frequency
Critical bands
76
Signal threshold (dB SPL)
75
74
73
72
71
70
50
100
200
400
800
1600
3200
Masking noise bandwidth (Hz)
Figure by MIT OpenCourseWare.
Tuesday, April 28, 2009
Critical bandwidth
2000
Critical Bandwidth (Hz)
1000
500
200
100
50
Tuesday, April 28, 2009
0.1
0.2
0.5
1
2
Center Frequency (kHz)
5
10
Center frequency
•
Bark scale
-
Zwicker and Fastl, 1990
#!
!
"
"2 $
0.76 f
f
B( f ) = 13 arctan
+ 3.5 arctan
1000
7500
25
Bark
20
15
10
5
0
2
10
Tuesday, April 28, 2009
3
10
Frequency (kHz)
4
10
Masking
•
Masking experiments to investigate
frequency selectivity
•
Tones masking tones demo
Amplitude
masker
probe
Frequency
Tuesday, April 28, 2009
100
80
dBspl
60
40
20
0
20
50
100
200
500
1k
2k
5k
10k
20k
Frequency (Hz)
Figure by MIT OpenCourseWare.
Zwicker and Fastl, 1990
Tuesday, April 28, 2009
Upward spread of masking
3
800Hz
0
b) Travelling waves
3
3
1600Hz
400Hz
0
0
"Unrolled" cochlea
Basilar membrane
Cochlear apex
Cochl
ear ba
se
Direction of sound
movement
Figure by MIT OpenCourseWare.
Tuesday, April 28, 2009
MP3 Compression
•
•
•
•
Perceptual coding
ISO Standard 1991
10 : 1 compression
Typical song size: 3.75 MB vs. 40 MB (CD
Original iPod (2001)
5GB = 1000 songs
Tuesday, April 28, 2009
Quantization
16 bits = 65536 levels
10 : 1 compression = 1.6 bits
Tuesday, April 28, 2009
Tone masking noise
Amplitude
masker
noise
noise level
noise
bandwidth
Tuesday, April 28, 2009
Frequency
Tone masking noise
Tuesday, April 28, 2009
Complex tones
Tuesday, April 28, 2009
Hearing
•
•
•
Tuesday, April 28, 2009
Sound localization
Perception of complex periodic sounds
-
pitch
timbre
Auditory scene analysis
Localization
A
Vision
Sound
B
Figure by MIT OpenCourseWare.
Tuesday, April 28, 2009
-20o: IDT = -200 µs
0o: IDT = 0 µs
20o: IDT = 200 µs
60o: IDT = 480 µs
-60o: IDT = -480 µs
90o: IDT = 640 µs
-90o: IDT = -640 µs
120o: IDT = 480 µs
-120o: IDT = -480 µs
-160o: IDT = -200 µs
180o: IDT = 0 µs
160o: IDT = 200 µs
Figure by MIT OpenCourseWare.
Tuesday, April 28, 2009
Interaural time difference
0.7
Interaural time difference (ms)
0.6
0.5
Measured values
(5 subjects)
0.4
0.3
0.2
0.1
0
0o
Front
20o
40o
60o
80o
100o
120o
Direction of sound source
140o
160o
180o
Back
Figure by MIT OpenCourseWare.
Tuesday, April 28, 2009
Interaural level difference
6000 Hz
10
0
4000
10
0
Interaural level difference (dB)
2500
10
0
1800
10
0
1000
10
0
500
10
0
200
10
0
0o
Front
30o
60o
90o
120o
Direction of sound source
150o
180o
Back
Figure by MIT OpenCourseWare.
Tuesday, April 28, 2009
Cones of confusion
?
?
Figure by MIT OpenCourseWare.
Tuesday, April 28, 2009
Auditory distance perception
•
•
Tuesday, April 28, 2009
Relative intensity
Spectral composition
Auditory distance perception
•
•
Tuesday, April 28, 2009
Relative intensity
Spectral composition
Complex periodic sounds
Pitch
Timbre
Amplitude
•
•
Time
Tuesday, April 28, 2009
Complex sounds: pitch
Amplitude (db)
Fundamental frequency
1
0
3
5
7
9
11
13
15
17
Harmonics Frequency (Hz)
19
21
23
6000
Figure by MIT OpenCourseWare.
Tuesday, April 28, 2009
Fundamental frequency
•
•
Tuesday, April 28, 2009
Lowest harmonic usually perceived pitch
Fundamental can be missing
Fundamental frequency
•
•
Lowest harmonic usually perceived pitch
Fundamental can be missing
0
Amplitude (dB)
−10
−20
−30
−40
−50
−60
261.6
523.2
784.8
1046.4
1308
Frequency (Hz)
Tuesday, April 28, 2009
1569.6
1831.2
Fundamental frequency
Lowest harmonic usually perceived pitch
Fundamental can be missing
0
0
−10
−10
Amplitude (dB)
Amplitude (dB)
•
•
−20
−30
−40
−50
−60
−20
−30
−40
−50
261.6
523.2
784.8
1046.4
1308
Frequency (Hz)
Tuesday, April 28, 2009
1569.6
1831.2
−60
261.6
523.2
784.8
1046.4
1308
Frequency (Hz)
1569.6
1831.2
500 (Hz)
750 (Hz)
b
1000 (Hz)
c
500 + 700
+ 1000 (Hz)
d
4 ms
4 ms
4 ms
4 ms
e
Figure by MIT OpenCourseWare.
Tuesday, April 28, 2009
Odd harmonics
•
Clarinet
-
cylindrical bore, closed at one end
0
−5
Amplitude (dB)
−10
−15
−20
−25
−30
−35
−40
−45
−50
262
785
1308
1831
2354
Frequency (Hz)
Tuesday, April 28, 2009
2877
3400
3923
Pitch illusion
Shepard tone
Amplitude
•
Hearing
threshold
Log frequency
Figure by MIT OpenCourseWare.
from Music, Cognition, and Computerized Sound, ed. Perry Cook
Tuesday, April 28, 2009
Mel scale
•
•
Stevens,Volkmann and Newman 1937
Equal in distance
1400
Interval size (MELs)
1200
Octave
1000
800
Fifth
600
400
200
0
64
128
256
512
1024
2048
4096
8192
Frequency (Hz)
Figure by MIT OpenCourseWare.
from Music, Cognition, and Computerized Sound, ed. Perry Cook
Tuesday, April 28, 2009
Pitch helix
Tone Height
•
•
Drobish (1855)
Shepard (1982)
F5
G5
B6
A6
F4
G4
F3
F2
A3
E3
B4
A4
G2
E4
B5
A5
G3
E5
E2
B3
C6
D5
C5
D4
C4
D3
C3
D2
C2
A2
Figure by MIT OpenCourseWare.
Tuesday, April 28, 2009
B2
Increasing
frequency
Musical scale notes
Complex sounds: timbre
•
•
•
•
•
Tuesday, April 28, 2009
Not well defined
Overtones
Formants
Attack and decay
Synchrony of microvariations
Harmonics fuse
•
•
Tuesday, April 28, 2009
Energy in harmonics typically falls off
Harmonics perceptible in unusual spectra
Harmonics fuse
Energy in harmonics typically falls off
Harmonics perceptible in unusual spectra
Amplitude
•
•
Frequency
Tuesday, April 28, 2009
Harmonics fuse
Energy in harmonics typically falls off
Amplitude
Harmonics perceptible in unusual spectra
Amplitude
•
•
Frequency
Frequency
Tuesday, April 28, 2009
Harmonics fuse
Energy in harmonics typically falls off
Amplitude
Harmonics perceptible in unusual spectra
Amplitude
•
•
Frequency
Amplitude
Frequency
Frequency
Tuesday, April 28, 2009
Throat Singing
Figure removed due to copyright restrictions.
Tuesday, April 28, 2009
Formants
•
Fixed resonances
A
B
'ah'
Amplitude (dB)
Amplitude (dB)
Piano
'ee'
Amplitude (dB)
Amplitude (dB)
Trombone
Frequency (Hz)
Figure by MIT OpenCourseWare.
Tuesday, April 28, 2009
0
Amplitude (dB)
−10
−20
−30
−40
−50
−60
0
1000
2000
3000
Frequency (Hz)
Tuesday, April 28, 2009
4000
5000
0
−10
−10
Amplitude (dB)
Amplitude (dB)
0
−20
−30
−40
−50
−60
0
−20
−30
−40
−50
1000
2000
3000
Frequency (Hz)
Tuesday, April 28, 2009
4000
5000
−60
0
1000
2000
3000
Frequency (Hz)
4000
5000
0
−10
−10
Amplitude (dB)
Amplitude (dB)
0
−20
−30
−40
−50
−60
0
1000
2000
3000
4000
5000
−40
−10
−20
−30
−40
−50
1000
2000
3000
Frequency (Hz)
Tuesday, April 28, 2009
−60
0
1000
2000
3000
Frequency (Hz)
0
Amplitude (dB)
−30
−50
Frequency (Hz)
−60
0
−20
4000
5000
4000
5000
0
−10
−10
Amplitude (dB)
Amplitude (dB)
0
−20
−30
−40
−50
−60
0
−20
−30
−40
−50
1000
2000
3000
4000
−60
0
5000
1000
0
0
−10
−10
−20
−30
−40
−50
−60
0
3000
4000
5000
4000
5000
Frequency (Hz)
Amplitude (dB)
Amplitude (dB)
Frequency (Hz)
2000
−20
−30
−40
−50
1000
2000
3000
Frequency (Hz)
Tuesday, April 28, 2009
4000
5000
−60
0
1000
2000
3000
Frequency (Hz)
Microvariations
•
Tuesday, April 28, 2009
modulations of harmonics can affect fusion
Microvariations
•
modulations of harmonics can affect fusion
Example
from Music, Cognition, and Computerized Sound, ed. Perry Cook
Tuesday, April 28, 2009
Attacks and decays
•
Basic transitions
-
attack, sustain, decay, release (ADSR)
http://en.wikipedia.org/wiki/ADSR_envelope
Tuesday, April 28, 2009
Instrument quiz
bassoon,
clarinet,
horn,
oboe,
piano,
sax,
synth,
trumpet
Tuesday, April 28, 2009
Instrument quiz
bassoon,
clarinet,
horn,
oboe,
piano,
sax,
synth,
trumpet
Tuesday, April 28, 2009
Instrument 1
Instrument quiz
bassoon,
clarinet,
horn,
oboe,
piano,
sax,
synth,
trumpet
Tuesday, April 28, 2009
Instrument 1
Instrument 2
Instrument quiz
bassoon,
clarinet,
horn,
oboe,
piano,
sax,
synth,
trumpet
Tuesday, April 28, 2009
Instrument 1
Instrument 2
Instrument 3
Instrument quiz
bassoon,
clarinet,
horn,
oboe,
piano,
sax,
synth,
trumpet
Instrument 1
Instrument 2
Instrument 3
Instrument 4
Tuesday, April 28, 2009
Instrument quiz 2
bassoon,
clarinet,
horn,
oboe,
piano,
sax,
synth,
trumpet
Tuesday, April 28, 2009
Instrument quiz 2
bassoon,
clarinet,
horn,
oboe,
piano,
sax,
synth,
trumpet
Tuesday, April 28, 2009
Instrument 1
Instrument quiz 2
bassoon,
clarinet,
horn,
oboe,
piano,
sax,
synth,
trumpet
Tuesday, April 28, 2009
Instrument 1
Instrument 2
Instrument quiz 2
bassoon,
clarinet,
horn,
oboe,
piano,
sax,
synth,
trumpet
Tuesday, April 28, 2009
Instrument 1
Instrument 2
Instrument 3
Instrument quiz 2
bassoon,
clarinet,
horn,
oboe,
piano,
sax,
synth,
trumpet
Instrument 1
Instrument 2
Instrument 3
Instrument 4
Tuesday, April 28, 2009
Attacks
Figure removed due to copyright restrictions.
Tuesday, April 28, 2009