CHANGING FRECUENCY

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JORGEMAL
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CHANGING FRECUENCY

Post by JORGEMAL » Wed Jul 15, 2009 7:12 pm

I am new to sound recording and I need to change the frecuency of an audio file. I need to test changing to frecuencies greater than 20,000 hz and below 20 hz, beyond the human audible range.

Is this posible with Audacity software? If so, I will very much appreciate if you tell me how.

With respect,
Jorge Maldonado

kozikowski
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Re: CHANGING FRECUENCY

Post by kozikowski » Wed Jul 15, 2009 7:53 pm

One of the complaints of Audacity is that it will manage "sound" that nobody can hear. It will manage sound with zero frequency, battery voltage, and there are actually well-used tools to get rid of that signal.

Higher is more of a problem. I think Audacity will cheerfully go up there, but you will need a sound specification that can follow you up. 44100 sample frequency will not go up reliably further than 17.8 KHz. Barely high audio. Figure a Nyquist number of 2.6. Highest audio frequency multiplied by 2.6 to get the sampling frequency. 36 KHz audio would need sampling of 96000. 36 KHz x 2.6 = 93600.

Most sound cards will not produce electrical signals at those frequencies. So you may not be able to get the performance out of the computer.

Koz

JORGEMAL
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Re: CHANGING FRECUENCY

Post by JORGEMAL » Thu Jul 16, 2009 3:00 pm

Thank you for your reply Kozikowski.
From your answer I understand that Audacity is able to achieve my goal but the problem lies on the sound card. Is this correct?
Does is mean that I need to find a sound card capable of generating the frequencies I need?

With respect,
Jorge Maldonado

steve
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Re: CHANGING FRECUENCY

Post by steve » Thu Jul 16, 2009 4:51 pm

What are you intending to do with these high/low frequencies? Do you need to "play" them? If so, what other equipment do you have? If not, what do you want to do with them?
9/10 questions are answered in the FREQUENTLY ASKED QUESTIONS (FAQ)

JORGEMAL
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Re: CHANGING FRECUENCY

Post by JORGEMAL » Fri Jul 17, 2009 1:56 pm

We are working in a project with subliminal audio messages and one of our tests has to do with changing the frequency of the audio files to values beyond the human perception which is 20hz-20000hz. After getting this result, we plan to play them in an audio component not in a PC.

Respectfully,
Jorge Maldonado

steve
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Re: CHANGING FRECUENCY

Post by steve » Sat Jul 18, 2009 11:45 am

JORGEMAL wrote:we plan to play them in an audio component not in a PC.
Is this "audio component" capable of reproducing frequencies outside of the audio range?
Do you have loudspeakers / headphones / amplifiers ... capable of handling frequencies below 20Hz/above 20kHz ?
9/10 questions are answered in the FREQUENTLY ASKED QUESTIONS (FAQ)

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