Answer: 261.6 Hz.

Why would we ever need to know the frequency of notes? Well, there could be a few different reasons, but one has to do with mixing audio. When equalizing (EQing) an audio track, one common challenge is filtering out background noise—especially if the track was recorded with a microphone. Here’s what the mic might be picking up:

• The rumble of a streetcar or truck going by in the distance
• An accidental knock of the microphone stand
• A door closing somewhere in your building

Your best route to eliminating background noise is to cut it out at the source… but in many cases (barring time travel) that’s just not possible. So, we use an equalizer, or EQ, to lend a helping hand.

Take a guitar track, for example. What’s the lowest sound you’d expect to come from a guitar? If it’s in standard tuning, the lowest string is tuned to E2, which has a frequency of 82.4 Hz (see the table below). This means that any sound below ~80 Hz is not guitar. So, if we filter out everything below that frequency, we cut out the low noise (like the streetcar rumble) but keep all that wonderful guitar sound. Not bad! The name for this kind of filter is a high-pass filter, because it lets all the high frequencies pass—and keeps out the low ones.

Below is a table of all the note frequencies, with the highest and lowest notes of various instruments highlighted. The first column is the octave number; for example, the low E string on a guitar is tuned to E2—that’s E in the 2nd octave.

NOTE: The frequency values above use the standard A4=440 Hz tuning system.

If you’re looking for some ear training to boost your mixing skills (and want to hear some cool EQing examples), check out our hearEQ video. You can also read up on audio and EQing with our Audio Primer (lots of audio samples), check out our tutorial on EQing an audio track, and even follow along as we EQ a podcast. Questions, comments, or want to see more instruments on our note frequency chart? Send us a note or feel free to leave a comment.