Sound intensity level

Definition

Sound intensity level is a logarithmic measure of the sound intensity relative to a reference value, typically measured in decibels (dB). It quantifies how loud a sound is perceived.

5 Must Know Facts For Your Next Test

1. Sound intensity level is measured in decibels (dB).
2. The reference sound intensity is usually $1 \times 10^{-12}$ W/m², which corresponds to the threshold of hearing.
3. Sound intensity level is calculated using the formula $$L_I = 10 \log_{10} \left(\frac{I}{I_0}\right)$$ where $I$ is the sound intensity and $I_0$ is the reference intensity.
4. A doubling of sound intensity results in an increase of approximately 3 dB in the sound intensity level.
5. The human ear perceives a 10 dB increase in sound intensity level as roughly twice as loud.

Review Questions

• What unit is used to measure sound intensity level?
• How does doubling the sound intensity affect the sound intensity level?
• What is the reference sound intensity ($I_0$) commonly used when calculating sound intensity level?

Related terms

Decibel (dB): A unit used to measure the intensity of a sound or the power level of an electrical signal by comparing it with a given level on a logarithmic scale.

Sound Intensity:

The power per unit area carried by a wave, measured in watts per square meter (W/m²).

$I_0$ (Reference Sound Intensity): $1 \times 10^{-12}$ W/m², which represents the threshold of hearing for humans.