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Author Topic: Can you test this frequency for me?  (Read 39723 times)
Oren
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« on: May 30, 2009, 09:16:16 PM »

Attached is a 15 second Ogg Vorbis file of a generated sine wave. I'd like to comfirm the frequency with  as many independent testers as possible. There is some concern that frequency  generators available on the web are inaccurate, and I'd like to get this right before proceeding with a new project.
Could you also please tell me what software/equipment you used to measure the frequency/pitch?
Thanks in advance for your help,
Oren.

* sine wave 15 seconds.ogg (31.36 KB - downloaded 293 times.)
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Alienz
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« Reply #1 on: May 30, 2009, 10:31:53 PM »

500hz?
This is actually the first time ive done something like this, I used the frequency analyzer in Audacity.
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folderol
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« Reply #2 on: May 30, 2009, 11:00:31 PM »

Hmmm, a very quick and dirty manual count of 50 peaks gives 527Hz which is very close to C (523.2511). However the accuracy of all of this is moot, as the actual rate will depend on the accuracy of your computer's internal clock Shocked

{edit}
I'll see if I can borrow a frequency meter from work and see how much difference there is in real time when this is played on different computers.
« Last Edit: May 30, 2009, 11:10:31 PM by folderol » Logged

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Oren
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« Reply #3 on: May 31, 2009, 02:26:48 AM »

Alienz, Will,

Thanks for getting back so quickly! Cool
 I'll hold back on revealing the actual frequency the software tried to generate in case I get more responses - I don't want to influence the test results.
Oren.
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offthewall
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« Reply #4 on: May 31, 2009, 11:47:10 AM »

This is using ReaTune in Reaper.

 Wink
James


* Pitch.gif (116.83 KB, 995x727 - viewed 589 times.)
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Alienz
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« Reply #5 on: May 31, 2009, 02:22:41 PM »

I'll try to use a tuner too later today
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MarioD
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« Reply #6 on: May 31, 2009, 03:47:11 PM »

Using the pitch change option in Audacity I get 531.325 Hz as the initial pitch.
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Oren
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« Reply #7 on: May 31, 2009, 04:17:40 PM »

Mario,
Audacity reads it as 531.325 Hz - thanks!

James,
Reaper measures 527.97 Hz - thankyou, too!

I'll  confide in you now that the sine wave was created by Audacity at 528 Hz.
Several sources on the web offer a sample of this frequency, and I've noticed that some of the samples are audibly different in pitch than others. The purpose of this little exercise is to determine if Audacity can create an accurately pitched sine wave.

Will's information leads me to believe that this is somewhat dependent on the computer in which Audacity is installed.

Oren.
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Alienz
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« Reply #8 on: May 31, 2009, 07:08:48 PM »

Same here Audacity pitch change : 531.325
Tuner says C +15
The plot spectrum option in Audacity seems to indicate more around 538 though  Huh

Now I remember why I never get into this kinda stuff... Cheesy


I'm on an Intell Q6600 win XP
« Last Edit: May 31, 2009, 07:20:42 PM by Alienz » Logged
Wyatt
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« Reply #9 on: May 31, 2009, 08:57:53 PM »

Audition clocks this @ 531.09

Cool

Wyatt
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folderol
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« Reply #10 on: May 31, 2009, 08:59:04 PM »

Hmmm. The actual synthesis of a sinewave in software should be far, far better than sampling an incoming signal in real time. A sine curve is a totally understood bit of mathematics, as is turning it into am amplitude/time graph. Once you have done that, you have to all practical purposes done the synthesis.

To get such divergent results is quite frankly deeply disturbing. Tomorrow I will check out the actual result with the frequency meter and about a dozen completely different computers!
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If you have a poem, I have a tune, and we exchange these, we can both have a poem, a tune, and a song.
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Oren
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« Reply #11 on: May 31, 2009, 09:09:07 PM »

Wyatt,
Thanks for checking in with your Adobe software! Audition measures it at 531.09 Hz.

Will,
My grasp of mathematics and physics is quite pathetic, but generating an accurately pitched 528Hz sine wave did not, initially, seem like much of a chore - until I heard the divergent results from different sources... Roll Eyes

Thanks again, gentlemen  Kiss
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folderol
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« Reply #12 on: June 01, 2009, 12:04:37 PM »

Calling in at work (naughty me Shocked)

Freqency tests on 7 machines Min. was 527.2 Max was 528 (this was on the eeepc)
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« Reply #13 on: June 01, 2009, 04:50:30 PM »

Same here 531,325 in Audacity 1.3, same result on win and linux machine

k
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folderol
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« Reply #14 on: June 01, 2009, 07:08:26 PM »

This is really weird. All the software interpreters seem to get it miles out, including (if I understand Oren correctly) the very software that created the file Shocked

Actual measured playback results (by yours truly) seem to be far closer, but with a surprising amount of variation.

Thinking more about this I wonder if the playback variation is due to the processor clocks, or is it due to a reference clock on the sound card itself.

Hmmm.
Just had another thought. All the computers at work have on-board sound. I wonder if they skimp on quality by using the main system clock instead of a dedicated sound one. I will see if I can 'borrow' the meter and bring it home, and see what results I get from my DAW (M-Audio 2496 sound card).

As an extra comment, the works meter quotes an accuracy of 0.01% +/- 1 least significant digit. It is quite a few years old now so I wouldn't actually be confident in it to more than 0.1%
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If you have a poem, I have a tune, and we exchange these, we can both have a poem, a tune, and a song.
- Will
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