http://www.nidcd.nih.gov/health/hearing/pages/hearingaid.aspx#hearingaid_05
http://www.mediacollege.com/audio/microphones/how-microphones-work.html
http://www.mediacollege.com/audio/01/sound-waves.html
http://www.yale.edu/ynhti/curriculum/units/2003/4/03.04.07.x.html
tp://en.NHD.eduht/Sonar
www.fi.edu/fellows/fellow2/apr99/soundvib.html
www.mediacollege.com/audio/01/sound-waves.
http://www.youtube.com/
www.fi.edu/fellows/fellow2/apr99/soundvib.html
www.mediacollege.com/audio/01/sound-waves.
http://www.youtube.com/