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 (P₁ and P₂) is defined as dB. 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 ✎

1. How many decibels correspond to doubling the pressure of a sound?

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

3. What does 0 decibels mean?

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