The Doppler effect explains changes in the length of light waves or sound waves as they move toward you or away from you.

VOA: special.2009.04.29

So to be clear, we expect most students to very comfortably pursue the standard edition of the P set, but for this particular P set, and we have about 150 or so of these out on the hallway, and we'll have them at office hours throughout the coming week--this is a little logic board ; with lots of sensors; the sound sensor, a light sensor, a little joystick and the like.

我希望我们大多数同学,研究问题集的标准版本，可编程版有个特殊的问题集，我们会在接下来的几周里，在办公时间为大家做解答,这是个小的逻辑板,上面有很多传感器;,包括声音传感器，光传感器，小操作杆等。

哈佛公开课 - 计算机科学课程节选

"Some of these inventors have been designers of the human genome sequencer, incredible technologies around focusing sound in the same way have been able to focus light with lasers, health technologies like the stair-climbing wheelchair and a portable dialysis machine,".

VOA: standard.2009.12.18

"Let's Shoot" "Light em all up" "Come on fire" (SHOOTING SOUND) In the incident, (SHOOTING SOUND) Wikileaks,the group that posted the video, has identified two of the men as a Reuters news photographer and his driver.

VOA: standard.2010.04.06