Is it possible to record frequency?

Question

If you produce a sound lets say, of a certain frequency, and record it thru a microphone, will the same frequency be translated thru the feedback of a stereo?

In other words, if I record a sound of a certain frequency will that specific frequency get reproduced in play back or will the recording interface (computer) replicate the sound but not it's specific frequency? Or are the two inseparable?

Answer 1

With a perfect microphone and perfect speakers, and perfect arrangement of the sound field, this would work this way.



However, with real hardware, you'll get effects very close to what you initially produced, however, it can't be avoided that certain unwanted harmonics will be added due to electronic (and acoustic) impurities.



Within given tolerance, it is doable. And if you produce a harmonic sound of a given frequency, and it's not affected by the medium, generally propagates without change, it will still be of the given frequency.



And the sound is a sum of it's harmonics, so it's non separable. Harmonics pretty much correspond to frequencies, but it's a huge simplification.

Answer 2

In imaging we encounter this dilemna all the time. To solve it you must remember the definition of accuracy and precision.



The best way to ensure that you record the true frequency is to calibrate your recording system. At each step, the microphone to the sound board, the sound board to the computer, computer to speakers etc... you should input a known frequency, say from a fork, and evaluate the signal produced, say with an electronic tuner. You then correct the device downstream for the error. If your recording software is advanced enough you can change how it records certain frequencies. It is best to have a single correction for the error over your entire system. It's also best to assume that your recorded file may be used on another system so I would suggest making sure the file you record has accurate frequencies in it an ignore calibrating the speakers.



If you actually try this bear in mind that the error of a device is usually not linear so don't expect to be able to shift the entire sound spectrum over by 3 Hz and be done; the error is likely different at any given frequency.

Answer 3

Didn't you ever listen to a recording of music?

Didn't it sound almost identical to the original?



A recording sounds like the original because the frequencies and amplitudes are reproduced.



You can't record a sound without recording it's frequency, and you can't play it back without reproducing that frequency. True, in older recording methods the frequency could be slightly different from the original, but only by a fraction of a percent.



And you don't need a computer to make or playback a recording.



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