Fig. 1.

Experiment setup photo. An ultrasound probe was put atop an ultrasound gel pad to measure the surface wave speed of the lung phantom—the purple sponge. The pink sponge and the black rubber were put under the purple sponge to reduce the reflection of the sound wave from harder surfaces. A shaker was in contact with the purple sponge surface to generate harmonic vibrations on the sponge surface. The bars behind the shaker and the ultrasound probe are the holder frames used to keep the equipment in place.