Why do Music Instruments sound different?:

Two different music instruments, playing the same tone, sounds different. The reason ist that (almost) all music instruments, besides the keynote -the one that "stands in the notes"- produce overtones. Overtones, or harmonics are tones higher than the keynote. They have frequencies of 1,5 - 2 - 3 - 4 etc. times the keynote. As an example two different organ pipes with same keynote:
Open pipe:
The tone is g: nominal 196 Hz, measured 193,8 Hz
The keynote is seen left, it is the largest. Towards right follows 1. harmonic, still strong, 2. harmonic somewhat weaker, and a weak 3. harmonic
The tone seems a little "sharp".

(The difference is hard to hear trough internet.)
Closed pipe:
The tone is g: nominal 196 Hz, measured 193,8 Hz
The keynote, left, is strongest. The 1. harmonic is very weak
2. harmonic is strong, and 3. and 4. harmonics are very weak.
The tone seems a little softer.

The two pipes has same keynote, but sound different. The harmonics are the reason.

Below some examples of music instruments. An oscilloscope shows the raw wave, and the spectrum analyzer shows the composition of the tone.

Click the oscillograph to learn what are keynotes, and harmonics.



1: Positive maximum of keynote and a harmonic
2: Positive maximum of harmonic
3: Negative maximum of keynote and a harmonic
4: Negative maximum of a harmonic.
5: Positive maximum of keynote, negative maximum of a harmonic.
6: Positive maximum of a harmonic.
7: Negative maximum of keynote, positive maximum of a keynote.

Mouth organ

Bamboo Whistle

Bamboo Whistle
This bamboo whistle has a damage that causes a wrong harmonic called a "wolf", at the red arrow. The whistle sounds bad.


African Lute

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