How to convert frequency to pitch

I saw somewhere that James Earl Jones’ speaking voice is around 85 Hz. What musical pitch is that?

Let P be the frequency of some pitch you’re interested in and let C = 261.626 be the frequency of middle C. If h is the number of half steps from C to P then

P / C = 2h/12.

Taking logs,

h = 12 log(P / C) / log 2.

If P = 85, then h = −19.46. That is, James Earl Jones’ voice is about 19 half-steps below middle C, around the F an octave and a half below middle C.

More details on the derivation above here.

There’s a page to do this calculation for you here. You can type in frequency or pitch and get the other back.

(The page also gives pitch on a Bark scale, something you may not care about that is important in psychoacoustics.)


Photo credit Wikipedia
Music image created using Lilypod.

7 thoughts on “How to convert frequency to pitch

  1. I’m a fan of using the A above/below middle C (3 half steps or 9 half steps, respectively). Below is 220 hz, above is 440 hz. Obviously the math works out the same, and I get 16.46 half steps below the A below middle C.

  2. Since 19.46 is so close to 19.5, you could also say that it’s near to F half-flat (F

  3. SteveBrooklineMA

    This reminds me of a problem I’ve wondered about. How do you take a piece of recorded music, and raise it an octave (or some number of semi-tones) electronically, without changing its duration? This is what Autotune does, I think. I don’t know of any clean mathematical way to do this. Intuitively it seems like something the Fourier transform was built for but I can’t get it to work out.

  4. James Earl Jones was awesome in Dr. Strangelove. “Negative function sir. The bomb bay doors are still closed.”

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