Sound Intensity = Power / Area (Watts / Meter2)

1
Sound Intensity Power / Area (Watts /
Meter2) 1 Bel Log10 (Sound Intensity1 / Sound
Intensity2) 10 Decibels (BD) 1 Bel Sound
Power Sound Pressure2 Sound Pressure Level
(SPL) in DBs 10 x Log10 (Power1 / Power0 )
20 x Log10 (P1 / P0 ) DB 0 gt P1 P0
Common Reference 0 DB 20 uN/M2 20
uPascals 20 ubars 1000 Hz Pure Tone
Barely Audible under Ideal Conditions
2
Equal Intensity Phon Base 1000 Hz Pure
Tone Second Tone (Different Frequency) Judged To
Be Equal Intensity 1 Phon Loudness of 1000
Hz _at_ 1 DB Example 1000Hz _at_ 40 DB same as 50 Hz _at_
65 DB Since 1000HZ _at_ 40 DB 40 Phon then 50
HZ _at_ 65 DB 40 Phon
3
Relative Intensity (Sone) Loudness of 1000 Hz _at_
40 DB 40 Phons 1 Sone Ten Fold Increase
Loudness Double the Sones Ten Fold Increase
Loudness (Increase by 10 DB) 2 Sones