Sound pressure and velocity pressure concepts vs loudness Here is my understanding and question:
Atmospheric pressure is around 101325 Pa.
Our ear drum is exposed to this pressure from both sides so total pressure is zero.
But when we hear sound, ear drum starts vibrating and the effective pressure on ear drum is calculated for many scenarios. For example a jet engine produces 632 Pa, our threshold of pain is 63.2 Pa.
In a wind-tunnel 15 m/s (54 km/h) wind speed corresponds to 140 Pa.
When I enter a wind tunnel I don't feel any pain with 140 Pa, but why do I feel pain with 63.2 Pa when it comes to sound.
It vibrates or not, isn't pain about the force on ear?
Why does sound waves with less pressure results pain but not a constant 140 Pa wind directly blowing to my ear? 
 A: I think there is a difference between the amount of pressure exerted on a flat surface by the fluid in a wind tunnel versus the amount of pressure that makes down your ear canal to your ear drum.  The wind in a wind tunnel is not directly incident on your ear drum.  I imagine if one could directly apply a 15 m/s flow onto the ear drum, it would hurt.  
Sound waves can cover a large range of frequencies/wavelengths and your ear can respond to frequencies between ~100-20000 Hz (give or take a few hundred Hz depending on age and the ear).  A jet engine produces a relatively sharp/narrow peak in frequency space (which falls within your ear's response) compared to the roughly white noise produced by the turbulence produced at the outside edge of your ear canal in a wind tunnel.  Thus, I think the sound waves from the jet engine are capable of imposing a larger gradient of pressure (i.e., force density) directly to your ear drum.  Whereas the white noise produced by the turbulence in the wind tunnel causes power to spread over a large range of frequencies/wavelengths, few of which are directly incident on the ear drum.
