Reflection
http://physics.bu.edu/~duffy/HTML5/reflection_transmission.html
Doppler Effect
Reflection free/fixed
Standing waves, harmonics, transvers, longitudinal
http://www.physicsclassroom.com/Physics-Interactives/Waves-and-Sound/Standing-Wave-Patterns
Reflection
Standing waves
Doppler Effect
Reflection and refraction
http://www.walter-fendt.de/html5/phen/refractionhuygens_en.htm