Reflection, Transmission and Absorption of Sound Waves

Echolocation in Bats and Dolphins:  Chromolama C, video from  BBC

Echolocation: Living Waters - Secrets of Dolphin Echolocation: Illustra Media

SONAR:  Scientists "See" Ocean Floor via Sonar:  National Geographic

Echocardiogram (Echo)

(Click link to watch on You Tube)

Echocardiogram:  Having an Echo:  Royal Children's Hospital Melbourse

Fetal Ultrasound:  How Ultrasound Works: Animed

Fetal Ultrasound:  3D Ultrasound 25 Weeks: Elena Wormington