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Symphony #1 in D |
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Last Movement |
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Outer Ear |
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Middle Ear |
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Inner
Ear |
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Just
Noticeable Difference |
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or |
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JND |
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100 % correct ̃ Certainty |
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50% Correct ̃ Guess |
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Cutoff is defined for 75% |
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Intensity
= I (W/m2) |
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Sound
Intensity |
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Level
= SIL (dB) |
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For two sounds, |
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A and B, |
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if IA/IB
= 2, |
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what to
we hear? |
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For two sounds, |
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A and B, |
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if SILA/SILB
= 2, |
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what to
we hear? |
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The phon is the unit of |
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Loudness
Level |
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( LL) |
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The LL
(in phons) of a sound is defined to
be numerically equal to the SIL (in dB) of a 1000 Hz tone that sounds
equally loud to the listener. |
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If note
A sounds twice as high in pitch as note B, it is found that the frequency
of A is twice that of B. |
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Natural unit of pitch is the Octave. |
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Simple relationship between pitch and frequency. |
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The
loudness of a sound depends on the frequency of the sound. |
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1. Play 1000 Hz at SIL=40 dB. |
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2. Play 100 Hz.
Ask listener to adjust for the same loudness. |
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3. Repeat for many frequencies |
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f(Hz) SIL (dB) |
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20 90 |
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50 64 |
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100 51 |
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500 38 |
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1000 40 defined |
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1500 40 |
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f(Hz) SIL (dB) |
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2000 39 |
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4000 32 |
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6000 36 |
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8000 49 |
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10000 48 |
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15000 41 |
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Auditory Demo CD |
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Tracks 17 and 18 |
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Hearing is most sensitive in the range 2,500 –
5,000 Hz. Why? |
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Ear canal is a tube closed at one end |
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l= 4L
= 4(2.5 cm) = 10 cm |
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f = v/l = 344m/s /0.1m = 3,440 Hz! |
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Notes