EQ & Audio Processing Guide
Everything you need to know about EQ, frequency bands, compressors, and fades.
Contents
What is EQ (Equalizer)?
An equalizer (EQ) lets you boost or cut specific frequency ranges in your audio. By adjusting different frequency bands, you can shape the character of a sound — clear up muddiness, add warmth, reduce harshness, and more.
Every recording has imperfections that live at specific frequencies. EQ lets you fix them surgically, targeting exactly the range where the problem lives. AudioBuff's presets automatically apply the right EQ settings for common use cases, so no technical knowledge is required.
Filter Types
EQ uses different filter shapes to adjust frequencies in different ways. AudioBuff uses four filter types.
- Peaking
- Boosts or cuts a specific frequency with a bell-shaped curve. The most versatile filter type — used for most EQ adjustments. Perfect for targeting a specific problem frequency.
- High Shelf
- Adjusts all frequencies above the set point together. Used to control overall brightness and "air." Boost to add sparkle to vocals, or cut to tame harsh high-end.
- Low Shelf
- Adjusts all frequencies below the set point together. Used to control the weight and warmth of the low end. Boost to add body, cut to reduce muddiness.
- High Pass Filter (Low Cut)
- Removes all frequencies below the set point. Excellent for eliminating low-frequency noise like AC hum, fan noise, and mic handling rumble without affecting the main audio.
Frequency Band Guide
Human hearing spans roughly 20Hz (very low) to 20kHz (very high). Each frequency range has distinct sonic characteristics. Use this table as a reference when deciding what to adjust.
| Band | Frequency | Characteristics & Use |
|---|---|---|
| Sub-bass | 20–60Hz | Felt more than heard. Rarely useful in voice recordings — cutting here cleans up the mix. Provides the foundation for kick drum and bass in music. |
| Bass | 60–250Hz | Warmth and weight of the sound. Boost for a richer, fuller low end. Cut to reduce muddiness and improve clarity. |
| Low-Mid | 250–500Hz | Body and fullness of voices and instruments. A little boost adds warmth, but too much causes a boxy, "muddy" sound. |
| Mid | 500Hz–2kHz | The core of vocal presence. Nasal tones, boxiness, and "telephone" sound live here. One of the most important ranges for voice. |
| Presence | 2k–4kHz | Vocal definition and intelligibility. Boost to bring vocals forward and make them more distinct. Cut to reduce harshness and listening fatigue. |
| High | 4k–6kHz | Consonant crispness and articulation. Boost for better intelligibility. Cut to soften sibilance ('s' and 'sh' sounds). |
| Air | 6kHz+ | Sparkle and openness. Boost for a brighter, more airy sound. Great for vocals and acoustic instruments. |
High Pass Filter (Low Cut)
A high pass filter removes all frequencies below a set cutoff point, allowing the higher frequencies to "pass through" — hence the name. It's also called a "low cut" filter.
For voice recordings, it's highly effective at removing low-frequency noise like AC hum, fan noise, and mic handling rumble. Setting it around 80Hz removes the noise while keeping the voice natural. For music, be careful not to set it too high — cutting above 60–80Hz can remove fundamental bass and kick drum frequencies.
AudioBuff lets you set the cutoff from 40Hz to 250Hz. For podcasts and narration, try 80–120Hz. For music, 40–60Hz is usually the safest range.
Compressor (Even Out Volume)
A compressor automatically reduces the dynamic range of audio — the difference between the loudest and quietest parts. When volume peaks above a set threshold, the compressor reduces the gain to bring it into line.
For spoken audio like podcasts, a compressor evens out the natural variation in speaking volume, making the whole recording more consistent and comfortable to listen to. It's one of the most commonly used tools in podcast and narration production.
For music, use compressors carefully. Too much compression flattens the natural dynamics that give music its emotional impact. AudioBuff's compressor is tuned for voice-oriented use.
Fade In / Fade Out
Fades smoothly transition audio between silence and full volume, eliminating abrupt starts and endings. They're one of the simplest ways to give audio a polished, professional feel.
- Fade In
- Volume gradually rises from silence at the start. Prevents an abrupt, jarring beginning. Even a 0.5 second fade makes a noticeable difference.
- Fade Out
- Volume gradually drops to silence at the end. Creates a clean, professional finish. Music tracks commonly use 2–5 second fade-outs.
AudioBuff supports fade durations from 0 to 5 seconds. Start with 0.5 seconds and adjust to taste.