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Hearing: Loudness

Measuring loudness

•  Loudness matching •  Start with one frequency at a given

intensity level •  1000Hz tone at 20dB

•  How loud do other frequencies need to be so that they sound as loud? •  adjust 100Hz tone so it sounds as

loud as the 1000Hz 20dB tone

Equal Loudness Contours Measuring loudness

•  Magnitude estimation •  Assign sounds numeric values

depending on how loud they sound

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Measuring loudness

Trial   dB   Approx  value  

Trial   dB   Approx  value  

1   +15   500   11   -­‐10   30  

2   -­‐5   50   12   +15   500  

3   -­‐20   10   13   +20   1000  

4   0   100   14   -­‐5   50  

5   -­‐10   30   15   +10   300  

6   +20   1000   16   -­‐15   20  

7   +5   200   17   -­‐5   50  

8   +10   300   18   -­‐20   10  

9   -­‐15   20   19   +5   200  

10   0   100   20   +15   500  

Measuring loudness

•  Magnitude estimation

Temporal integration

•  Adding up sound energy over time •  100 msec sounds louder than 10 msec

Loudness coding

•  We can perceive a range of 130dB •  But AN fibers respond over a much smaller

range

Loudness coding

•  Can we rely on different cells with different ranges?

Loudness coding •  Look at pattern across cells with different

CFs.