PowerPoint Presentation

A brief message from your TAsTine GulbrandsenWahab Hanif Pure Tones are Very Rare in Nature!What are real sounds composed of?2Pure Tones are Very Rare in Nature!What are real sounds composed of?

Virtually all sounds are composed of several (or many) frequencies all going at once3Pure Tones are Very Rare in Nature!What are real sounds composed of?

Virtually all sounds are composed of several (or many) frequencies all going at once

Extra frequencies are called harmonics4What are harmonics?positionupdownimagine a guitar string:

5What are harmonics?positionupdown

imagine a guitar string:6What are harmonics?time ->positionupdownBut more than one frequency can fit between the end points

7What are harmonics?time ->positionupdownf0f1f2In fact many frequencies can be superposed.

8Properties of a Sound WaveA 1 second, 1 Hz sound wave:

9Properties of a Sound WaveA 1 second, 2 Hz sound wave:

10Properties of a Sound WaveA 1 second, 3 Hz sound wave:

11Properties of a Sound WaveWhat would happen if two or more sound waves were happening at the same time?12Properties of a Sound WaveSounds superpose (they add together)

13Properties of a Sound WaveSounds superpose (they add together)

14Properties of a Sound WaveIf most sounds are made of several frequencies, then which sound determines the pitch that you hear?15Properties of a Sound WaveIf most sounds are made of several frequencies, then which sound determines the pitch that you hear?

Typically you hear the lowest frequency component as the pitch of a complex wave16Properties of a Sound WaveThe lowest frequency is called the fundamental17The Missing FundamentalYour brain so likes to track the fundamental of a set of harmonics that it will perceptually fill it in even when it is absent

missing fundamental18Timbre (pronounced like: Tamber)pure tones are very rare

a single note on a musical instrument is a superposition (i.e. several things one on top of the other) of many related frequencies called harmonics

Pronounciation of timbre19Timbrethe characteristic of a particular set of harmonics is called timbree.g. the set of harmonics generated when a particular key is pressed on a pianotimbre is one reason why we can tell the difference between the same notes played on difference instruments

20TimbreAlthough any musical note is a superposition of harmonics, you still hear it as a single pitch (you hear its tone height)

The pitch that you hear is (usually) the fundamental frequency (except in the artificial case of the missing fundamental)

21Musical Intervalsin music, notes are played together or in quick successionpairs of notes share a relationship called an interval

22Musical IntervalsWithin each pair, the higher pitch (f2) is some multiple of the lower pitch (f1):e.g. 200 hz and 400 hz -- f2 is two times f1

23Musical Intervalsf1= 400 f2 = 800 (f2 = 2 x f1)octave f1= 400 f2 = 600 (f2 = 3/2 x f1)perfect 5thf1= 500 f2 = 800(f2 = 8/5 x f1)minor 6thf1= 400 f2 = 550(f2 = 11/8 x f1)

octaveperfect 5th

minor 6th

not quite a perfect fourth?!24Consonance and DissonanceConsonance is the degree to which two tones played together sound good

Dissonance is the opposite

25Consonance and DisonanceDissonance seems to increase with increasing complexity of the ratio of the tones

26Seeing Sound with SpectrogramsA spectrogram is a 3D plot of soundTimeFrequencySeeing Sound with SpectrogramsA spectrogram is a 3D plot of soundTimeFrequencyIntensityIntensity is often coded by colour such that red is high and blue is low