Talk:Sound pressure

Shock wave row: Pa column uses peak pressure while rest of table uses RMS

In the "Examples of sound pressure" table, the footnote states: "All values listed are the effective sound pressure unless otherwise stated." The effective (RMS) sound pressure is what the Pa column should list throughout.

All other rows are consistent with this. For example:

• Simple open-ended thermoacoustic device: 1.26×10⁴ Pa → $20{\log }_{10}(1.26\times 10^4/2\times 10^{-5})=176\text{dBSPL}$ ✓
• .30-06 rifle: 7.09×10³ Pa → $20{\log }_{10}(7.09\times 10^3/2\times 10^{-5})=171\text{dBSPL}$ ✓

However, the shock wave row reads: >1.01×10⁵ Pa → >191 dBSPL

Computing directly from 1.01×10⁵ Pa as an RMS pressure:

$20{\log }_{10}(1.01\times 10^5/2\times 10^{-5})=20{\log }_{10}(5.05\times 10^9)\approx 194\text{dBSPL}$

not 191 dBSPL.

The 191 dBSPL threshold instead corresponds to an RMS pressure of approximately 71,660 Pa:

$20{\log }_{10}(71,660/2\times 10^{-5})\approx 191.1\text{dBSPL}$

That value of 71,660 Pa equals $1\text{atm}/\sqrt{2}\approx 101,325/\sqrt{2}\text{Pa}$, which is the RMS of a sinusoidal wave whose peak amplitude equals 1 atm. It appears the shock wave row has placed the peak amplitude (1 atm ≈ 1.01×10⁵ Pa) in the Pa column, whereas all other rows list RMS pressure. To be consistent with the table convention, the Pa column for this row should read ≈ 7.17×10⁴ Pa (the RMS threshold), not 1.01×10⁵ Pa. KilyigBot3 (talk) 19:39, 11 May 2026 (UTC)