Hearing is believing…
...Music is deceiving
Night time sharpens, heightens each sensation
Darkness wakes and stirs imagination
Silently the senses abandon their defences
Helpless to resist the notes I write
For i compose the Music of the Night
Slowly, gently, night unfurls its splendour
Grasp it, sense it, tremulous and tender
Hearing is believing, music is decieving,
Hard as lightning, soft as candlelight,
Dare you trust the Music of the Night
Sensory system: hearing
•Interpretation of refined sensory organs: evolutionary role
•Sound, acoustics, Fourier theorem
•Weber-Fechner law, Stevens-law
•Fletcher-Munson curves, decibel, phon, son scales
•Anatomy of human ear, signal amplification
•Mechanism of hearing: Helmholtz, Békésy, flat curves vs.
resolution
music sounds:
ω 2ω 4ω
f t   c0  c1 sint  1   c2 sin2t  2   ...  cn sinnt  n 
(ω = 2Π/T)
What is
the
pitch?
simple
resonance
Békésy
Helmholtz
http://jn.physiology.org/cgi/content/abstract/104/3/1219
„traveling
surface waves”
1961 Nobel
Prize in
Physiology or
Medicine
frequency
(stimulus)
oval
apex
window
Place theory of
frequency coding:
loud
soft
rel. deflection
Lower frequency
sounds stimulate
hair cells more
distant from
staple.
distance from oval window mm)
Cross-section of inner ear
basal membrane, longitud.
section
Structure of hair cells
Stereocilia on the surface of the hair cells
http://depts.washington.edu/tempelab/06NuB502_3F_HC.ppt.
http://www.santafevisions.com/csf/h
tml/lectures/006_hearing_I.htm
amplification: prestin +
Development of the excited state in hair cells
stereocilia
depolarization
nucleus
vesicles
synapse
Afferent
neuron
neurotransmitter
to brain
frequency
(stimulus)
oval
apex
window
Place theory of
frequency coding:
loud
soft
rel. deflection
Lower frequency
sounds stimulate
hair cells more
distant from
staple.
distance from oval window mm)
Nature Reviews Neuroscience 7, 19-29 (January 2006)
passive mech.
active mech.
(outer hair cells.)
base
Deflection
amplitude
http://physicsweb.
org/articles/world/
15/5/8
outer hair cells.
(basal m.)
apex
Prestin
molecules
distance from oval window
coarse cochlear
frequency analysis refined in
the nervous system by lateral
inhibition → contrast formation
32,000
myelinated
cochlear nerve
fibers
Assessment of loudness
• ”How many times is it louder?”
• ”IS IT LOUDER?”
– „if a person could consistently feel that
a 110 g weight was heavier than a 100
g weight, he could also feel that 1100 g
was more than 1000 g.”
ΔI= kI
Weber, 1830:
minimal percieved change of I
Fechner, 1850:
I
ΔL ~ Δ I /I
ch. of sens.
reference I
Weber-Fechner:
L = konst lg I/ Io
rel. ch. of stim.
Stevens, 1950:
I
ΔL/L ~ Δ I /I
rel. ch. of sens. rel. ch. of stim.
n
L = konst [I/ Io ]
loudness
intensity
pressure
Threshold of
pain
Loudness of
human
speech
I
H  10 lg s (decibel)
I0
I1000
H  10 lg
(phon)
I0
0.3
1 I 
H    ( son)
16  I 0 
dB
watt/m2
hearing threshold
0
10-12
whisper
20
10-10
speech
40 - 60
10-8 - 10-6
80
10-4
shouting
engine noise
90 - 120
pain threshold
120 - 130
10-3 - 1
1 - 10
standing waves:
http://www.walter-fendt.de/ph14hu/stwaverefl_hu.htm
http://fenykapu.free-energy.hu/pajert/index.htm?FoAblak=../pajert2/Allohullam.htm
hair-cell regeneration:
http://depts.washington.edu/hearing/InnerEarHairCellRegeneration.php
prestin movie:
http://www.hei.org/research/cmb/cellstru/cellstru.htm
recent papers on the exact role of prestin, etc.:
Silencing the Cochlear Amplifier by Immobilizing Prestin
Volume 58, Issue 3, 8 May 2008, Pages 299-301
Cell: Volume 139, Issue 1, 2 October 2009, Pages 33-44
consonance-dissonance:
http://vaczy.dk/htm/scales.htm
http://www.cs.indiana.edu/~port/teach/641/audition.for.linguists.Sept1.html