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Unformatted text preview: The unit of measurement for loudness levels is the phon , and is arrived at by reference to equal-loudness contours. By definition two sine waves, of differing frequencies, are said to have equal-loudness level measured in phons if they appear equally loud to the average young person without significant hearing impairment. Loudness level (phon) An equal-loudness contour is a measure of sound pressure ( dB SPL ), over the frequency spectrum, for which a listener perceives a constant loudness when presented with pure steady tones. Phon is equal to the sound pressure level in decibels at f = 1 kHz Hearing sensitivity is maximum near the first resonant frequency 3.5 - 4.0 kHz of the outer ear canal, and has another peak at the second resonance ~13kHz sone 1 2 4 8 16 32 64 128 256 512 1024 phon 40 50 60 70 80 90 100 110 120 130 140 Loudness of pure tones (sone) ( 29 10 / 40 2- = L L S Loudness S in sones: L L Loudness level in phones: Loudness level (see previous slid) has been constructed using sound pressure level, which is logarithmic function of intensity. Because of that loudness level is slow function of intensity. Sone has been introduced to “return beck “ Loudness level, and sone are based on the average listener sensation of loudness....
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- Fall '09