MEASUREMENT OF SOUND REFLECTION COEFFICIENTS AS A FUNCTION OF FREQUENCY IN AN UNDAMPED TANK

摘要

We discuss a technique for measuring the frequency-dependent acoustic reflection coefficient of a material under test in a tank where the acoustic waves reflected by the tank surfaces cannot be neglected. The effectiveness of this technique was assessed by measuring the reflection coefficient at the air–water and water–reinforced-concrete interfaces. We describe the experimental results obtained at low frequencies (down to a few tens of hertz), in addition to several special considerations that apply to low-frequency measurements.