How to Draw Custom EQ Curves in Audacity

Achieving professional voice recordings often requires compensating for a microphone's natural tonal imbalances, room resonances, or proximity effect. Audacity provides a built-in tool called Filter Curve EQ that allows users to manually draw and customize frequency response curves to tailor audio to perfection. This guide explains how to open the Filter Curve EQ, manipulate custom curve points, apply essential microphone corrections, and save the settings as reusable presets.

Accessing the Filter Curve EQ

1. Open your audio project in Audacity.
2. Select the audio track you want to adjust by clicking its track panel, or press Ctrl + A (Cmd + A on Mac) to select the entire project.
3. Navigate to the top menu and select Effect > EQ and Filters > Filter Curve EQ.

Understanding the Interface

The Filter Curve EQ window displays a graph where:

• The horizontal axis represents frequency in Hertz (Hz), spanning from sub-bass (20 Hz) to upper treble (20,000 Hz).
• The vertical axis represents volume adjustment in decibels (dB), allowing you to boost (positive dB) or cut (negative dB) specific frequency bands.
• The green line across the center at 0 dB represents your audio's current, unaltered state.

How to Draw and Edit Custom Curves

• Add a point: Click anywhere directly on the green line to create a new control point.
• Adjust gain and frequency: Click and drag an existing point up or down to boost or cut the signal, or drag it left and right to shift the target frequency.
• Delete a point: Click and drag a point off the top, bottom, or sides of the graph grid to remove it.
• Flatten the curve: Click the Flatten button at the bottom of the window if you need to reset the curve to 0 dB and start over.

Common Microphone Corrections to Draw

Every microphone model interacts differently with voice types, but several standard adjustments can be drawn to clean up most vocal tracks:

• Low-End Rumble Removal (High-Pass): Create a point at approximately 80 Hz and pull the line to the left of it down to -30 dB or lower. This eliminates mic handling noise, desk thumps, and low-frequency electrical hum without thinning out the voice.
• Clearing Mud (Proximity Effect): Microphones placed close to the mouth often capture excessive boominess. Add a point around 250 Hz to 350 Hz and pull it down by 2 to 4 dB in a gentle dip to clarify speech.
• Reducing Harshness and Sibilance: Cheap or overly bright condenser microphones often produce piercing "s" sounds. Place a gentle dip between 5 kHz and 7 kHz of around 2 to 3 dB to soften sharp consonants.
• Adding Presence or "Air": If a dynamic microphone sounds dull or muffled, place a point at roughly 10 kHz to 12 kHz and gently elevate it by 1 to 3 dB using a broad, smooth rise to enhance vocal breath and clarity.

Previewing, Saving, and Applying

1. Click the Preview button in the lower-left corner to listen to a short sample of your audio with the custom curve applied.
2. To save the curve for future recordings, click Presets & Settings > Save Preset..., name the preset according to your microphone model, and click OK.
3. Once satisfied with the curve, click Apply to render the tonal changes onto your selected audio track.