Thanks for the explanation (maybe a little patronizing, but I assume it’s in good faith). I found that 105 db is the average human pain threshold, and that NIOSH suggests a maximum exposure of 4.72 minutes at this db level. Still I don’t know how long is an amber alert signal, but AFAIK they are played at the hardware max volume, bypassing the software limitations of the device, so maybe it was that.

Regarding the energy, mechanical energy tends to follow the path of least resistance, which for the ear is still the tympanic membrane with it’s 0.1 mm thickness. Excluding hairs, which are extremely rare and small in a kid’s outer ear canal, every other structure has a density far more superior, and with density comes inertia which impedes a swift “air to tissue” energy absorption. In a system like this a minimal imperfection in the eardrum tissue (and no tissue is perfectly regular in the human body) is a weak point which can lead to rupture. Also the ear canal is usually a mild funnel, so there’s also an ulterior compression of the air happening inward and towards the eardrum.

As for resonances, I too don’t think that they play a significant role in the case.