Audacity Forum

Hello,
I´m not sure, how can I read from the Frequency Analist the main frequency. There are a few peaks, so the main is the highest?
Also I´ve read the the Manual, but I still don´t understand it. Can you help me?

Thanks

The higher a peak is, the louder that frequency will sound, so a peak at 1000Hz that shows as -20dB will sound a lot louder than if the peak only went up to -30dB.
This does NOT mean that 2 peaks at different frequencies that have the same vertical height in the display will sound the same loudness. This is for 2 main reasons -
1) higher frequencies have a lot more energy than lower frequencies (imagine swinging a skipping-rope so that it goes round once per second (1Hz) and then speeding it up so that it goes round 20 times per second (20Hz) - clearly 20Hz requires a lot more energy.
2) human hearing is more sensitive at middle frequencies than at very high or very low frequencies.

To get the idea, try creating some sounds using the "Generate menu" functions. Listen to them, then look at them in the Frequency Analysis window.

It is usually more useful to set the "Axis" to "Log Frequency". This spaces out the frequency grid making it easier to "read".

Also, have a look here: http://en.wikipedia.org/wiki/Audio_frequency

leqiza wrote:Hello,
I´m not sure, how can I read from the Frequency Analist the main frequency. There are a few peaks, so the main is the highest?
Also I´ve read the the Manual, but I still don´t understand it. Can you help me?

Thanks

what do you mean by main frequency?

if the peaks are all multiples (eg harmonics) then the main one is the one on the left
and the ones to the right should each be getting smaller than the previous.

there may be other peaks. and they may have harmonics.
either one could be "main" depending on your application.

ok, probably I should epress better...I want to measure the frequency of ringing rod, and the analyzer shown me a few "main" (the loudest sound´s) frequencies.
Do you think, that is it possible?

leqiza wrote:.I want to measure the frequency of ringing rod

You mean the sound that is made when you hit the rod with something? If the rod is free to vibrate, there will usually be a big peak followed by several smaller peaks as you look left to right. The big peak on the left is likely to be the "main" frequency. If you select a section of the sound after the sound starts to die away, the peaks to the right will diminish. These higher peaks are "overtones" (harmonics) of the "main" (fundamental) frequency. The fundamental frequency will depend not only on the dimensions and material that the rod is made of, but how it is "suspended". If you hold a metal rod at the centre and strike it you will get a low fundamental - if you suspend the same bar at a point 1/3 of the way along you will get a higher fundamental frequency. If the bar is not free to vibrate (for example if it is just lying on the ground) it will just go "clank" and there "note" will be indeterminate (there will be no one specific frequency, just a whole bunch of frequencies).

Yes, I hit the rod. I did, what you´d written and couldn´t find the fundamental frequency. But I found several peaks "far" about 1000Hz from each other. So they´re the overtones, and overtones (higher harmonics) are the multiples of the fundamental frequency. But I´ve calculated, that the fundamental frequency of the metal rod, which was hit at centre is somewhere above 2000Hz...