Finding Sine Frequency of sound

[Jtsou]

How do i find the frequency of a certain recorded sound off of audacity? I have highlighted the section of sound that I wanted to find the frequency, and clicked analyze->Plot spectrum. They give me some values but I dont know which one is correct.

If you want, you can download the file here:

http://www.fileden.com/files/2009/5/3/2 ... fdtone.mp3



From what i can gather, the first tone is 389hz, and the second tone is 989hz. However i have no idea if this is correct.

Thanks

[kozikowski]

They're all correct. If you have a complex noise, you will get many multiple peaks in the analysis. Be sure and increase the sample rate to at least 8000 or 9000 for accuracy.

http://www.kozco.com/tech/audacity/piano_G1.jpg

One of my favorite graphics. That's one piano note. It's actually not G1. I think it's two and a half octaves down from middle C.

If you have a pure tone like from a flute or tuning fork, then yes, you might get only one peak in the analysis.

You can't actually hear pure power line hum and interference in your live performance. What you can hear is the buzz that electrical interference causes because it isn't a pure tone. It's energy looks like that piano note.

Koz

[kozikowski]

It's 1000 Hz, or more accurately, 977 Hz. The next peak up is 2931 the third harmonic which means the tone has clipping distortion. There's probably a bunch more, but they all died in the MP3 compression of your sample.

Pull the analysis window really large on your screen and switch to Log display and 8192 sampling.

Koz

[Jtsou]

Thank you for the replies they were really helpful