acoustic impedance acoustic shadow acoustical oceanography adiabatic albert beaumont wood american civil war battle of iuka beryllium boltzmann constant bulk modulus celsius density deuterium digital digital object identifier dispersion relation elastic modulus flight instruments frequency group velocity heat capacity ratio helium ideal gas isaac newton kelvin kilogram lapse rate mach number mean free path microphone microsoft excel miles per hour newton nitrogen noble gas optical fiber oxygen ozone layer pacific ocean particle displacement particle velocity particle velocity level phase velocity pitot tube pressure project mogul rayleigh number refraction refractive index relativistic euler equations sofar channel salinity second sound shear modulus sonar sound sound barrier sound energy density sound energy flux sound intensity sound intensity level sound power sound power level sound pressure sound speed gradient special relativity speed steel stratosphere surface temperature thermodynamics time toy model tuning fork ultrasound underwater acoustics van der waals equation water wave world ocean atlas xenon yttrium iron garnet