Sound underwater distance and decibels

[hongiddong]

I was wondering if sound underwater traveled further than sound in air? It seems like it wouldn't do to viscosity. I know that it travels faster however.

Lastly, is the online reasoning for why we can't hear sound as well underwater correct: the water vibration bypasses some of the sensory mechanisms and vibrations of the ear drum, but instead vibrates the mastoid process?

 

[davenn]

I was wondering if sound underwater traveled further than sound in air? It seems like it wouldn't do to viscosity. I know that it travels faster however.

for a given amplitude and frequency, yes it does.
It also travels at different speeds depending on the density of the water ... depth and composition are two controlling factors

Whales use sound over many 100's of km's to communicate

my sensors regularly pick up sound waves transmitted through the ocean from seafloor earthquakes 1000's of km away ... around 4000 km is my current personal record Dave

 

[sophiecentaur]

Lastly, is the online reasoning for why we can't hear sound as well underwater correct: the water vibration bypasses some of the sensory mechanisms and vibrations of the ear drum, but instead vibrates the mastoid process?

Our ears have specifically evolved to transform the vibrations in the air, which are 'low impedance' (small variations in pressure and relatively large displacement of a light medium) to the sensors in the cochlea which is a high impedance (very little displacement and higher variations in pressure). The ear drum is light weight and very flexible and the ossicles behave as levers to reduce the movement and increase the force of the vibrations. The ear drum is doing just the wrong job to couple sound from water effectively. The vibrations tend to be better transmitted through the bones of the skull and the fluid in the head. What we hear under water is far from 'hi fi' because the frequency response of that path has not been tiffled over the generations.