Intensity and Relative Intensity Level
|P||power of sound source||W|
|r||distance from sound source||m|
|β||relative intensity level||decibels (dB)|
|I0||threshold of hearing = 10-12 W/m2|
Tips to Remember
- Relative intensity level is less formally referred to as the “decibel level” of a sound. It is not the same as intensity; relative intensity level uses a logarithmic scale to more accurately reflect how humans perceive loudness.
- When you enter 10-12 into your calculator for the threshold of hearing, enter either “10^-12” or, if you use the scientific notation button, “1E-12.” Do not enter “10E-12” if you use the scientific notation button, because that would really be 10 × 10-12, or 10-11.
- Don’t be surprised if the problems you encounter have seemingly low sound powers. Your normal speaking voice produces only about a millionth of a watt of sound; our ears are just so sensitive that that’s enough.