Sound for Interaction class 5
Contents
Interference and Beats
adding sound waves
- Interference and Beats
http://www.school-for-champions.com/science/soundbeat.htm
Difference between two notes is called interval
Frequency and Pitch
Frequency if the measure of how many cycles a wave complete per second.
Frequency (f) is measures in Hertz
Period (T) in the inverse of infrequency is is measured in seconds
Frequency = Cycles/Second Perdiod = Seconds/Cycle
f = 1/T T = 1/f
The perception is frequency is know as pitch.
Intervals
An octave is doubling of the frequency.
ie 440 Hz is an A
the next A after 440 Hz is 880 Hz
In westen music the octave is divided into 12 semi-tones
http://thinkzone.wlonk.com/Music/12Tone.htm
http://en.wikipedia.org/wiki/Interval_(music)
http://www.musicalintervalstutor.com/
http://www.keystrokepublishing.com/html/sight_singing_tips.html
Phase
Phase in measured in degrees.
The phase of a sound has to do with the time domain.
Adding two Simple Harmonic waves -Applet
Adding two Simple Harmonic waves2 - Applet
http://library.thinkquest.org/19537/java/Wave.html
Timbre/Harmonic structure
Timbre is a descriptive word used to help describe the 'color' and envelope of a sound.
All sound is made up of simultaneous sounding tones. In the 1700 Joseph Fourier a French mathematical physicist proved that all sound can be synthesized be adding sine waves. The way these sine waves are added together make things sound different.
http://www.gac.edu/~huber/fourier/
Different sound don't sound the same due to different fundamental frequencies, harmonics, complexity, and envelope.
Timbre is made up of Harmonics and Envelope. The Harmonics define the different frequencies present in a a sound and the envelope defines the amplitude through time.
Harmonic Structure
http://www.rane.com/par-t.htm Harmonics defined @ rane
Understanding Harmonics Fundamental Frequency and Harmonics
Instruments
* Guitar string * Open-End Air Columns * Closed-End Air Columns
Natural harmonics are multiple of the fundamental/
Understanding Harmonics @ Harmony Central
http://ptolemy.eecs.berkeley.edu/~eal/eecs20/berkeley/scale/demo/timbre.html
http://www.umanitoba.ca/faculties/arts/linguistics/russell/138/sec4/source.htm
http://library.thinkquest.org/19537/cgi-bin/showharm.cgi
