In the same way as the mechanical properties, the acoustic properties could be obtained from an indirect method or by direct measurements using sophisticated apparatus.
The indirect methods consists of measuring several characteristic curves of the specimen (acoustic impedance, absorption and reflection) and, using the Biot theory, we can find the value of the material intrinsic properties from them.
The direct methods allow the value of the property to be obtained, measuring some related magnitude, for example, charge losses in pressure when an air current flow through the material. This uses expensive apparatus and it remains a very difficult way to measure with precision and reliable calibration.