Sensitivity of ear as a function of frequency
loudness level in Phons
tones of different frequencies have the same number
of phones if they sound equally loud.
the comparison tone is a 1000 Hz tone.
example: If a 1000 Hz tone has intensity level of 60 db
it is said to have 60 phones - any other equally loud
pure tone of different frequency also has 60 phones.
highest sensitivity of ear for about 2000 - 5000 Hz
DEMO: decrease sound press for 100Hz and for 2000Hz tones by same factor (same dB) - 100Hz becomes inaudible
Application: HiFi volume control vs loudness control
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