# 声压

（重定向自声压等级

## 聲壓

${\displaystyle p_{\mathrm {rms} }={\frac {p_{\mathrm {peak} }}{\sqrt {2}}}}$

${\displaystyle p_{0}=2\times 10^{-5}\,\mathrm {Pa} }$

${\displaystyle p\propto {\frac {1}{r}}}$

## 聲壓級

${\displaystyle \mathrm {SPL} =10\log \left({\frac {p}{p_{0}}}\right)^{2}\,\mathrm {dB} }$

## 與其他聲學物理量的關係

${\displaystyle I=pv}$
${\displaystyle I={\frac {p^{2}}{z}}}$

• v 是粒子速度，單位是米每秒（m s-1）。
• z 是媒質的特徵聲阻，單位為瑞利（rayl）。

${\displaystyle I_{0}={\frac {(2\times 10^{-5})^{2}}{400}}=10^{-12}\,\mathrm {W\,m^{-2}} }$

${\displaystyle \mathrm {SIL} =\mathrm {SPL} }$

## 一些聲壓和聲壓級的例子

(Pa)

(dB)

Simple open-ended thermoacoustic device[1] 12,619 Pa 176 dB

M1加蘭德步槍開火點一米的位置 5,023 Pa 168 dB
30米外的客機引擎 632 Pa 150 dB
Threshold of pain 63.2 Pa 130 dB

Hearing damage（possible） 20 Pa approx. 120 dB
100米外的客機引擎 6.32 – 200 Pa 110 – 140 dB

10米外的公路 2×10−1 – 6.32×10−1 Pa 80 – 90 dB
Hearing damage（over long-term exposure, need not be continuous） 0.356 Pa 85 dB[3]
10米外的汽車 2×10−2 – 2×10−1 Pa 60 – 80 dB
EPA-identified maximum to protect against hearing loss and other disruptive effects from noise, such as sleep disturbance, stress, learning detriment, etc. 70 dB[4]
Handheld electric mixer 65 dB

## 參考資料

1. ^ Hatazawa, M., Sugita, H., Ogawa, T. & Seo, Y.（Jan. 2004），‘Performance of a thermoacoustic sound wave generator driven with waste heat of automobile gasoline engine,’ Transactions of the Japan Society of Mechanical Engineers (Part B) Vol. 16, No. 1, 292–299. 存檔副本. [2012-01-30]. （原始内容存档于2012-02-23）.
2. ^ Swanepoel, De Wet; Hall III, James W; Koekemoer, Dirk. Vuvuzela – good for your team, bad for your ears (PDF). South African Medical Journal. February 2010, 100 (4): 99–100. PMID 20459912.
3. William Hamby. Ultimate Sound Pressure Level Decibel Table. （原始内容存档于2010-07-27）.
4. ^ EPA Identifies Noise Levels Affecting Health and Welfare, 1974-04-02 [2010-11-01]