Re: What is the specific acoustic impedence of a soundwave?

Acoustic impedance is a way of measuring something like the "stiffness" of
a medium with respect to the passage of sound waves.  Without looking at
your text, I can't be sure, but typically a term like _specific_ acoustic
impedance would then imply an acoustic impedance per unit amount of
material.  Now, the interesting physics comes up when you try to transmit
waves from a medium with one impedance into a medium with some other
impedance, either higher or lower.  At the boundary between the two media,
some of the incident energy in the wave will be transmitted and some will
be reflected.  This is true of sound waves hitting water, light waves
hitting glass, electrical signals in a coaxial cable hitting a connector
into another type of cable, etc.  The relation between the impedances in
each medium will determine what fraction of the energy of the wave is
transmitted and what fraction is reflected.  Those fractions are the
transmission coefficient and the reflection coefficient.  Intensity is just
another way of refering to energy here, so intensity reflection coefficient
means the fraction of the intensity (or energy) which would be reflected at
the boundary between two sound-carrying media with different impedances
("stiffnesses" or "resistances" to sound transmission).  You can read more
about the topics of impedance, transmission, and reflection in mechanical
systems in the book Vibrations and Waves by A.P. French.  Chapter 8 covers
this material (though perhaps at a bit higher level than your coursework so
far).