# The Naked Scientists Forum

### Author Topic: Harmonics and Overtones  (Read 3129 times)

#### hamza

• Full Member
• Posts: 88
##### Harmonics and Overtones
« on: 05/10/2007 05:24:25 »
While studying the phenomena of Stationary waves, i was wondering what  the difference is between HARMONICS and OVERTONES. I was confused at figuring them out. Like; is the second Harmonic called the first Overtone or is the other way round.. Help me with this..

#### lyner

• Guest
##### Harmonics and Overtones
« Reply #1 on: 05/10/2007 22:47:34 »
As I see it - and in my experience of specifying quartz crystals for accurate oscillators:
Harmonics are exact multiples of a fundamental frequency.
Overtones refer to the frequencies that you can get out of a vibrating system, in practice. A string or a column of air (trumpet etc.) can be made to vibrate at a fundamental frequency and then at frequencies at about two, three, four etc.  times the fundamental, BUT, because the effective ends of the standing waves are not exactly in the same place at all these frequencies, the effective length is not the same so the actual frequencies at which you get resonance are not exact harmonics. These frequencies are called overtones.  In brass instruments the overtones may be wildly out and this accounts for the colour of the sound. You have to compensate for this with lip pressure etc.
In a circuit, you may use a crystal that is designed and specified, because of how it is made, to oscillate at its second overtone.
If you use the crystal in the wrong circuit and get it to oscillate at  its fundamental frequency, then pick off and amplify the third harmonic, the frequency you get will  be near the second overtone but may not be accurate.
So harmonics are just maths and overtones are affected by practicalities.
Why their names should be out of step with each other I have no idea.

#### hamza

• Full Member
• Posts: 88
##### Harmonics and Overtones
« Reply #2 on: 06/10/2007 08:39:41 »
Thankx Sophiecenataur for your explanation.So, If i did not get u wrong, can i say that the 2nd Harmonic is the first ovetone , 3rd harmonic the 2nd overtone and so on???

#### lyner

• Guest
##### Harmonics and Overtones
« Reply #3 on: 06/10/2007 22:32:37 »
yup!

#### The Naked Scientists Forum

##### Harmonics and Overtones
« Reply #3 on: 06/10/2007 22:32:37 »