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Q & A: sound harmonic amplitudes

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Most recent answer: 10/22/2007
Q:
If a person is singing a song, the waveform of the sound signal will contain the fundamendal frequency of the tune and also the harmonics of it and some higher frequencies components (characteristics of the singer`s voice timbre). Will the instantaneous "frequency and magnitude spectrum" analysis of the sound signal show "the magnitude is maximum at the fundamendal frequencies always"?
- vimal (age 21)
Anna University, India
A:
First, we have a caveat. You can't quite take an "instantaneous" spectrum, because you can't define what frequency a wave is at unless you've allowed enough time to establish a pattern. Still, we can talk about taking the spectrum on a reasonably quick time scale.

That said, there is no reason at all for the fundamental to have to have the largest amplitude. Small loudspeakers often can't even reproduce the lowest fundamentals of some music, yet our brains automatically figure out the fundamental from its harmonics.

Mike W.

(published on 10/22/2007)

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