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Topic: How to measure the Frequency (Hz) of the sound? (Read 24687 times) previous topic - next topic
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How to measure the Frequency (Hz) of the sound?

Hi!
I need to measure the real value of the tone, lets say 432Hz.
Is it possible to measure the frequency (Hz) with foobar2000v136?
If not - which application should I use?
Thank's in advance.
dr. Nedev

Re: How to measure the Frequency (Hz) of the sound?

Reply #1 –
Since you are mostly interested in a numerical aspect of a sound, a frequency spectrum will not help you there, except if you find one with lots of precision (since you are trying to find the difference between 432 and 440).

Maybe this will do it:  http://www.sonicvisualiser.org/screenshots.html , although it isn't probably the type of automatic scan that you could be looking for.

I guess it could be possible to use an engine similar to the one that is used in that program (i've read that there is a VAMP plugin for that, which could be used to make a plugin for foobar...).

10X, JAZZ

Reply #2 –
Yes it is exactly what I am trying to measure - What are the differences between 432 and 440 Hz tone.
I believe that you are aware why is this important.
Thanks a lot for the prompt replay, JAZZ

Re: How to measure the Frequency (Hz) of the sound?

Reply #3 –
I know about the discussion about those two tuning frequencies, not much more.
What I do know for sure is that the tone has an effect on the mood, and lower ones cause more sadness, whereas higher ones cause more happiness.

Re: How to measure the Frequency (Hz) of the sound?

Reply #4 –
You want to do a Fourier transform of the audio stream. Usually audio gets decoded or stored in the time-domain, which is amplitude over time. The Fourier transform will transform the signal to the frequency-domain, which is amplitude over frequency. From that you can determine the amount of amplitude/power at a certain frequency.

A good freeware tool to calculate the Fourier transform is Audacity for example. Analyze->Plot spectrum will show you the frequency-domain spectrum. You can select the samples in question and inspect the frequency spectrum for them.
It's only audiophile if it's inconvenient.

Re: How to measure the Frequency (Hz) of the sound?

Reply #5 –
Quote
I need to measure the real value of the tone, lets say 432Hz.
If you have a pure-tone (a pure sine wave), spectrum analysis will give you the answer.

Quote
Yes it is exactly what I am trying to measure - What are the differences between 432 and 440 Hz tone.
Audacity can also generate tones at 432 or 440Hz (or any other frequency) if you want to listen to the difference.

There isn't much difference and if you don't have perfect-pitch you won't be able to tell if you are listening to 432 or 440Hz, unless you've just listened to one of the tones and you can hear if the next one is higher, lower, or in-between.   People with normal hearing (people without the gift of perfect-pitch) don't have good "pitch-memory."

Quote
I believe that you are aware why is this important.
It's simply a standard tuning reference.   Modern* instruments are tuned to A=440Hz.   It's a way to tune the whole orchestra to play the same notes and a way to build instruments to a standard so they can play together.   Many instruments can't be re-tuned (horns, & woodwinds, etc.) and it takes many hours to tune/re-tune a piano.   You need some standard so everybody can play together, and A=440 is the standard.

All real world sounds contain harmonics & overtones (that's why a guitar sounds different from a trumpet, even when playing the same note).   And of course, music contains many notes & chords, and thousands of frequency components.    

And obviously,  music contains many notes.  But not all songs contain all notes.     You can find songs played with instruments tuned to the normal 440Hz standard that don't contain any A-notes!  And, there are 8 A-keys on the piano, so it's possible to have A-notes in a song but no A4 (440Hz).

You can ASSUME that ALL music you are listening to is tuned to the 440Hz standard.    If you want to "transpose" your recordings, just pitch-shift EVERYTHING down by 1.8%.    (Audacity or any other audio editor can pitch-shift.)



P.S.
If you simply want to avoid 440Hz, you can use a notch filter to remove 440Hz without pitch-shifting and without affecting anything else.
 
*  A=440Hz was standardized sometime in the 1800s.    I'm guessing that tuning became standardized when the technology became available to measure frequency scientifically.    Without some standard instrument builders in different cities couldn't build instruments that could be played together.      



Re: How to measure the Frequency (Hz) of the sound?

Reply #6 –
432Hz is "important" in that it is a bit of crazy pseudoscience about the god note or resonance of the universe or some such. Some actual musicians actually believe it's a better tuning standard. We discussed it a bit before here and here.

Re: How to measure the Frequency (Hz) of the sound?

Reply #7 –
You can check the frequencies quickly in foobar with Add Location commands:
tone://440,3
tone://432,3

Don't forget to lower foobar's volume when playing pure tones or you'll blow up your ears.