Harmonics on a string

Simple harmonic motion:

http://positron.ps.uci.edu/~dkirkby/music/html/demos/SimpleHarmonicMotion/index.html


Harmonics on a stretched string/spring - "standing waves"

http://zonalandeducation.com/mstm/physics/waves/standingWaves/standingWaves1/StandingWaves1.html


Superposition (adding) of waves:

http://www.phy.ntnu.edu.tw/ntnujava/index.php?PHPSESSID=83b90d00c3a8b37a065ec5abe61acb7f&topic=19.msg124#msg124

Adding harmonics with instruments:

http://www13.fisica.ufmg.br/~wag/transf/TEACHING/ONDAS/Library_thinkquest/Harmonics.html