Wednesday, March 13, 2013

Microcassettes and Adobe Audition

Here's an interesting question that came out from left field. I haven't had a microcassette question in years, but here it goes. It turns out, someone is still using an old tape recorder out in the field and recorded interviews at 1.2 cm/s to double the available recording time on the tape (the original standard microcassette, the MC60, gives 30 minutes recording per side at its standard speed of 2.4 cm/s, and double that duration at 1.2 cm/s). But, now, that tape's needed for court. What do you do to get rid of the "chipmunks" that have inhabited your editing bay?

I'm assuming that you can play it into Adobe Audition, and that your input/record settings are ready to go. We'll start the fixing process once the record session is complete ... what to do with the file.

The command that you're looking for is called Interpret Sample Rate, found in the Edit menu. Since there's only two settings possible on the recorder, 2.4 cm/s and 1.2 cm/s - if you've got chipmunks ... it's been recorded at the 1.2 cm/s setting. In this case, reduce your sample rate by half. I know, it seems counter intuitive, but it works (think time-lapse video).

The nice thing about this process is that if you digitize your tape at a sample rate of 44,100 Hz, reducing the sample rate to 22,050 Hz won't really affect the audible quality of the file - since we're just talking about human speech (interviews).

Try it and see for yourself.

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