Answer :
Answer:
The pressure of noise in the atmosphere is commonly referred to as **sound pressure**. Sound pressure is a measure of the force of sound on a surface area perpendicular to the direction of the sound. It is usually measured in pascals (Pa) or in decibels (dB) when comparing it to a reference value.
### Key Points:
1. **Sound Pressure Level (SPL)**:
- SPL is a logarithmic measure of the effective pressure of a sound relative to a reference value. It is expressed in decibels (dB).
- The reference value is typically 20 micropascals (µPa), which is considered the threshold of human hearing.
2. **Measurement**:
- Sound pressure can be measured using devices like microphones and sound level meters.
- The measurement involves capturing the variations in atmospheric pressure caused by sound waves.
3. **Calculation**:
- SPL in decibels can be calculated using the formula:
\[
SPL (dB) = 20 \log_{10} \left( \frac{p}{p_0} \right)
\]
where \( p \) is the root mean square sound pressure and \( p_0 \) is the reference sound pressure (20 µPa in air).
4. **Relevance**:
- Understanding sound pressure is crucial in fields such as acoustics, audio engineering, and noise control.
- It helps in assessing the impact of noise pollution and designing measures to mitigate it.
### Examples of Applications:
- **Environmental Noise Monitoring**: Assessing the noise levels in urban areas to ensure they are within permissible limits.
- **Audio Equipment Design**: Ensuring that speakers and microphones accurately reproduce sound without distortion.
- **Hearing Protection**: Designing ear protection devices that can effectively reduce harmful sound pressure levels.
For more detailed information, you can refer to sources like textbooks on acoustics, publications by organizations such as the American National Standards Institute (ANSI), and educational websites dedicated to physics and sound engineering.
the pressure of noise in the atmosphere is called sound pressure.