Simple Rubber Tube Mimics Birdsongs (video) Harvard John A. Paulson School of Engineering and Applied Sciences Share Print E-Mail Loading video... Caption A close-up of the solitary wave as it moves through the tube, imaged by placing a mirror to show the mouth of the tube. Following a refractory period, the process repeats itself. Credit Harvard SEAS Usage Restrictions with credit Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.