What's Twice as Loud?

We have discussed sounds that are equally loud. What about sounds twice as loud?

Experiments have shown that an increase of somewhere between 5 and 10 dB will sound twice as loud:

• most people heard 5 dB as less than twice as loud
• most people heard 10 dB as at least twice as loud

In more research-controlled environments, for a 1000-Hz sinusoid at moderate to high levels, a difference of 10 dB doubles the loudness.

This serves as the basis for another scale of loudness called the sone.