### Home > A2C > Chapter Ch11 > Lesson 11.3.2 > Problem 11-150

11-150.

Logarithms are used to measure the “loudness” of sound. Decibels (dB) are logarithmic units used to descrbe a ratio of two levels of intensity or pressure. The difference between two levels of sound pressure (

*P*_{1}and*P*_{2}) is defined asdB. Usually, when decibels are used to describe just one sound, it is assumed that that sound is being compared to a reference level of 20 micropascals. Homework Help ✎_{}How many decibels correspond to doubling the pressure of a sound?

What is the sound pressure of a sound described as 60 dB?

What does 0 decibels mean?

How many times more pressure is in a sound of 40 dB than of 20 dB?

10 log(2) ≈ 3.0

*P* = 20 · 10^{6} = 2 · 10^{7}

The sound ratio is 1.

100 times more pressure.