Sound pressure level

Definition

Sound Pressure Level (SPL) is a measure of the pressure variation caused by a sound wave, relative to a reference value. It is typically expressed in decibels (dB).

5 Must Know Facts For Your Next Test

1. SPL is calculated using the formula $SPL = 20 \log_{10}(\frac{P}{P_0})$, where $P$ is the measured sound pressure and $P_0$ is the reference sound pressure, usually $20 \mu Pa$.
2. Decibels are a logarithmic unit, meaning that an increase of 10 dB represents a tenfold increase in sound intensity.
3. Human hearing ranges approximately from an SPL of 0 dB (threshold of hearing) to around 120-140 dB (threshold of pain).
4. SPL can be influenced by factors such as distance from the sound source and environmental conditions like temperature and humidity.
5. In acoustics, SPL is crucial for understanding how loud sounds are perceived and for designing systems that manage noise levels.

Review Questions

• What is the reference sound pressure level used for calculating SPL?
• How does an increase of 10 dB affect the perceived loudness of a sound?
• What range of SPL can typically be perceived by the human ear?

Related terms

Decibel (dB): A logarithmic unit used to express the ratio between two values, commonly used to measure sound intensity.

Sound Intensity: The power per unit area carried by a sound wave, typically measured in watts per square meter ($W/m^2$).

$P_0$: $20 \mu Pa$, the standard reference sound pressure level used in calculating SPL.