Threshold of Pain
The upper sound intensity limit above which acoustic vibrations cause physical discomfort and immediate structural damage to human ears.
Governing formula
I_pain ≈ 1 W/m² (120 - 130 dB SPL)
SI unit
W/m² (120-130 dB)
In depth
Intensity is one trillion times ($10^{12}$) stronger than the threshold of hearing.
Examples in the real world
Standing directly adjacent to a jet engine at full takeoff thrust (~130 dB).