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Harmonic Series and Spectrograms. 220 Hz (A3). Instrument 2. Sine Wave. Instrument 1. Why do they sound different?. Waveform. Piano. Guitar. Sine Wave. Overtones.
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220 Hz (A3) Instrument 2 Sine Wave Instrument 1 Why do they sound different?
Waveform Piano Guitar Sine Wave
Overtones • Overtones occur at integer multiples of the fundamental frequency when an object vibrates. The addition of these tones at regular intervals is musical to the human ear. • Example: Fundamental (1st Harmonic): 220Hz • 1st Overtone (2nd Harmonic): 440Hz • 2nd Overtone (3rd Harmonic): 660Hz
Spectrogram Piano Guitar
Frequency Decomposition: Pure Sine Wave T = 2ms f = 1/T f = 500Hz
Frequency Decomposition: Pure Sine Wave T = 1ms f = 1/T f = 1000Hz
Waveform Piano Guitar Sine Wave
Piano: Component Sine Waves Composite Wave (From Previous Slide) Original Piano Wave Look how close with only three sine waves!!!
Fourier Series • Any wave (sound) can be mathematically represented as some combination of sine waves. • Wave= SineWave1+SineWave2+SineWave3+… • Examining a wave as a Fourier Series lets us see the component frequencies that make up the unique sound!
Why you should change strings A quick experiment with a spectrogram New Old