How to Remove 60Hz Buzz and Harmonics in Audacity

Electrical ground loop interference typically manifests as a low 60 Hz hum or a harsher, brighter buzz caused by its harmonic frequencies (120 Hz, 180 Hz, 240 Hz, and above). This guide provides direct, step-by-step methods to remove both the fundamental 60 Hz frequency and its upper harmonics in Audacity using the Notch Filter, Nyquist Prompt, and Spectrogram tools without degrading your primary audio.

Method 1: Using the Notch Filter for Targeted Removal

The Notch Filter cuts a very narrow band of sound, eliminating the targeted electrical noise while leaving neighboring frequencies intact.

  1. Open your audio file in Audacity.
  2. Select the entire track by pressing Ctrl + A (Windows) or Cmd + A (macOS), or highlight the specific section you want to clean.
  3. Navigate to Effect > EQ and Filters > Notch Filter.
  4. Set the Frequency (Hz) to 60.
  5. Set the Q (Quality Factor) between 2.0 and 5.0. (A higher Q creates a narrower notch, affecting less of the surrounding audio).
  6. Click Apply.
  7. If the buzz persists, it is due to harmonic overtones. Repeat the process for the most common harmonics by changing the Frequency to 120, then 180, and 240 as needed.

Method 2: Removing All Harmonics at Once with Nyquist Prompt

Instead of applying individual notch filters manually, you can use a simple Nyquist script to cut the 60 Hz fundamental and its multiples simultaneously.

  1. Select your audio track (Ctrl + A / Cmd + A).
  2. Go to Tools > Nyquist Prompt.
  3. Paste the following code into the command box:
(setf f 60)
(setf q 4)
(setf harmonics 8)
(dotimes (i harmonics s)
  (setf s (notch2 s (* f (1+ i)) q)))
  1. Click Apply.

Note: This script notches out the first 8 harmonics of 60 Hz (60, 120, 180, 240, 300, 360, 420, and 480 Hz) using a Q factor of 4.

Method 3: Visual Removal Using Spectrogram and Spectral Edit

For complex buzz with variable or higher-order harmonics, using the Spectrogram allows you to visually identify and remove the exact frequencies.

  1. Click the dropdown menu next to the track name on the left side of the waveform and select Spectrogram.
  2. Look for persistent, solid horizontal lines running across the audio. The lowest strong line will be at 60 Hz, with additional lines stacked evenly above it (120 Hz, 180 Hz, etc.).
  3. Switch your selection tool to the Spectral Selection tool.
  4. Hover over the 60 Hz line until the cursor turns into a horizontal line with up/down arrows, then click and drag a narrow box around the line.
  5. Go to Effect > EQ and Filters > Spectral Edit Multi Tool (or Spectral Edit Parametric EQ).
  6. Apply the effect to carve out the selected band.
  7. Repeat for the brighter harmonic lines visible further up the frequency spectrum.

Method 4: Audacity Noise Reduction (Alternative)

If the buzz spans dozens of high-frequency harmonics that sound like a constant sizzle, the standard Noise Reduction tool can capture the entire profile at once.

  1. Highlight a section of the track that contains only the buzz (room tone where nobody is speaking or playing).
  2. Go to Effect > Noise Removal and Repair > Noise Reduction.
  3. Click Get Noise Profile.
  4. Select the entire track (Ctrl + A / Cmd + A).
  5. Open Effect > Noise Removal and Repair > Noise Reduction again.
  6. Set the parameters:
    • Noise Reduction (dB): 6 to 12 (higher values can cause a hollow, "underwater" sound)
    • Sensitivity: 6.00
    • Frequency Smoothing (bands): 3
  7. Click OK to apply.