Your eyes are also unable to see infrared, or ultra-violet, yet either with sufficient power will blind you. In fact it's often much more dangerous than visible light, because the light won't trigger your blink reflex.
Sound is just vibration in the air, and if the pressure is high enough, you're going to suffer. High frequency ultrasound is used for various medical treatments, most of which involve localised killing of cells.
>> I would say that if the ear does not pick up the energy above 20khz, then it cannot be harmed either.
> Your eyes are also unable to see infrared, or ultra-violet, yet either with sufficient power will blind you.
Sufficient power delivered by IR radiation can easily set you on fire, regardless of whether the part of you that's burning was sensitive to light or not. And UV can do much nastier things.
But it's hard for them to have any effect without depositing energy. It's absolutely correct that if an ear, or anything else, doesn't pick up energy from whatever you're throwing at it, it cannot be harmed.
Why worry about hearing specifically as a target for ultrasonic damage? As you yourself point out, sound can deposit energy regardless of the particular physical structure it's hitting. Delivering enough IR to the ear will destroy your hearing, but not because of any property of your hearing or your ears. Is there reason to believe that ears or hearing are more sensitive to ultrasound than, say, your nose is?
