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计算介质的特征声阻抗。
Acoustic Impedance
420.18 Pa s/m (Rayl)
Acoustic Impedance vs Medium Density
公式
## Characteristic Acoustic Impedance Acoustic impedance determines how much sound pressure results from a given particle velocity in a medium. ### Formula **Z = rho * c** - *rho* = medium density (kg/m3) - *c* = speed of sound in the medium (m/s) Air: about 415 Rayl. Water: about 1.48 million Rayl. Large impedance mismatches cause strong reflections at boundaries.
计算示例
Air at sea level (rho = 1.225 kg/m3, c = 343 m/s).
- 01Z = rho * c
- 02Z = 1.225 * 343
- 03Z = 420.2 Rayl
常见问题
Why does impedance mismatch cause reflections?
When a sound wave hits a boundary between two media with different impedances, part of the energy is reflected. The greater the mismatch, the more reflection. This is why sound barely penetrates from air into water.
How is acoustic impedance used in medical ultrasound?
Different tissues have different impedances. Reflections at tissue boundaries create the contrast in ultrasound images. Coupling gel is used to reduce the air-skin mismatch.
What are the units?
Rayl (Pa s/m) in SI. One Rayl equals one pascal-second per metre. Named after Lord Rayleigh.
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