Sound Links

The following links use images or videos to explain tricky concepts in sound. Enjoy!

Classes of Waves

Sound is a longitudinal wave, which means that it displaces the medium in which it travels in a direction parallel to its propagation. This is in contrast to the way most people intuitively draw waves, which is with the displacement perpendicular to the direction of propagation.

Transverse/Longitudinal Wave Youtube (Slinky):

https://www.youtube.com/watch?v=ilZj8JUTvy8

Transverse/Longitudinal Wave Youtube (Animation):

https://www.youtube.com/watch?v=MoVz2ENJb8M&index=2&list=PL047E4D930892831D

Beat Frequencies

Visual explanation of constructive vs. destructive interference:

http://hyperphysics.phy-astr.gsu.edu/hbase/sound/interf.html#c4

Partially constructive interference:

http://www.kutl.kyushu-u.ac.jp/seminar/MicroWorld2_E/2Part1_E/2P12_E/sin_wave2_super_E.jpg

Complex waveform due to partially constructive interference in a violin:

http://www.ccp14.ac.uk/ccp/web-mirrors/isotropy/~stokesh/vwave.jpg

Explanation of how the “beat” is created:

http://hyperphysics.phy-astr.gsu.edu/hbase/sound/beat.html#c3

Example audio samples of different beats:

http://en.wikipedia.org/wiki/Beat_(acoustics)#Sample

Production of Sound:

(Vocal cords)

https://www.youtube.com/watch?v=-XGds2GAvGQ

Doppler Effect:

Video of car horn w/ Doppler Effect:

https://www.youtube.com/watch?v=p-hBCcmCUPg

Wikipedia page w/ animations explaining the Doppler Effect (need to scroll down a little within the “General” section to the bolded word “Proof,” just above the next section, “Analysis,” and click the link that says “Show” if you don’t see animated GIFs.):

http://en.wikipedia.org/wiki/Doppler_effect#General