At this point I am most interested in the effects on speed and direction, but would be interested in any other factors found to influence sound waves.
Did you see the Wikipedia page:
http://en.wikipedia.org/wiki/Sound_velocity ?
It doesn't mention magnetic field at all, but there you will find many interesting points. You may not expect any specific effect of magnetic field on sound speed in gases and liquids (leave ferrofluids for a while). Therefore the solids are interesting, and among them the magnetostrictive materials in the first place. A steady magnetic field will imitate increased pressure and/or effectively change the Young modulus of the material (its stiffness), thus influencing the speed of sound (see the formulas in Wikipedia) in form of longitudinal waves (like the ones in gases and liquids). Periodically varying magnetic field may create something like a diffraction grating in ferrofluids, with all the consequences concerning the propagation of sound. I skip the discussion of shear waves, which are possible in solids (thin films in particular). Anyway, this is probably the case involving sound waves' direction changes.
One more effect has been experimentally confirmed: a sensitive microphone can "hear" the Barkhausen noise, that is the one created while the magnetic material is being (de)magnetized. Its source is the movement and reorientation of magnetic domains.
I haven't seen any papers dealing directly with sound waves in magnetic materials, but there are some dealing with magnons propagation. Unfortunately, magnons are not phonons.
Thanks for your comments Marek. It is so important to ask questions in the right way, for all people and you have helped me to see how my question is perceived by others.
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