Trane TRG-TRC007-EN manual Phon and Sone

period two

Sound Perception and

Rating Methods

notes

Phon and Sone
	120				loudness level (phons)
						120
Pam
	100					110
20						100
						90
ref	80
						80
dB
						70
pressure,	60
						60
	40					50
sound						40
	20					30
						20
	0					10		10,000
	20	50	100	200	500	1,000 2,000	5,000
					frequency, Hz			Figure 31

The phon is another descriptor used to indicate loudness with a single number. The loudness of a sound, expressed in phons, is equal to the sound- pressure level of a standard sound, at 1,000 Hz, that is considered equally loud. For example, a sound pressure level of 40 dB at 1,000 Hz is considered to have a loudness of 40 phons. Any sound that falls on this same loudness curve, at any frequency, would also be described as having a loudness equal to 40 phons.

While the phon scale is logarithmic, the sone is the linear equivalent to the phon. In principle, the sone scale is linear when compared to the response of the human ear. For example, two sones is twice as loud as one sone, and half as loud as four sones.

While the phon and sone scales are not widely used, some HVAC equipment, primarily non-ducted fans and power ventilators, is still rated in sones. AMCA Standard 301, Methods for Calculating Fan Sound Ratings from Laboratory Test Data, provides a method for calculating the sone rating from octave-band data. Use caution when comparing equipment based on sones. Multiple methods exist for calculating a sone rating, and they provide different results.

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