with those determined using thicker specimens and a conventional through transmission ultrasonic method table 1 differing by only a few percent this difference falls within the uncertainty ascribed to the conventional measurement when used to measure the acoustic velocity of water the resonance technique yielded a value essentially equivalent to that reported in the literature sources of error for the resonance technique include error in determination of the resonant frequency wire thickness and sample alignment or nonuniformities in the specimen thickness which lead to a broadening of the resonance the resonant frequency can bc determined more accurately by sampling more points problems with specimen alignment can bc mitigated through a well designed apparatus and careful experimentation the wire thickness is important for determination of the velocities but drops out of the equation for the poisson 39 s ratio the resonance technique presented should prove particularly useful for measurement of the mechanical properties of materials which exist perhaps only as thin subwavelength layers such as adhesives or highly attenuative materials the use of a fluid couplant medium provides for uniform and repeatable coupling of the sound into the specimen the capability for measuring both velocities on a single sample becomes especially useful when multi component polymer systems are being tested because of the variations within and between batches in addition to the poisson 39 s ratio and acoustic velocities if the density p of the specimen is known the young 39 s shear and bulk moduli e u03b1 and k can also be calculated via the familiar relations equ7 it is implicit that the properties measured are dynamic in many instances however the temperature of the specimen.