Audio Editing Fundamentals

Master the essential audio post-production techniques—normalization, compression, EQ, and noise reduction—using the correct processing order to achieve professional-quality audio.

When to Use This Skill

• Editing podcast episodes or video soundtracks
• Cleaning up recorded voiceovers
• Improving audio quality for marketing content
• Preparing audio files for distribution
• Troubleshooting common audio issues
• Standardizing audio levels across a project

Methodology Foundation

Source: iZotope + Industry Best Practices

Core Principle: Audio processing must happen in the correct order—each step builds on the previous. "Noise reduction before compression prevents amplifying noise. Compression before EQ prevents undoing your level work." The goal is to serve the content, not showcase the processing.

Why This Matters: Poor audio editing is the most common reason otherwise good content sounds amateur. Understanding these fundamentals enables marketers to polish recordings themselves or effectively communicate with audio engineers.

What Claude Does vs What You Decide

What This Skill Does

1. Applies correct processing order - Gain → Noise → Compression → EQ → Limiting
2. Sets appropriate levels - Normalization, loudness standards (LUFS), peak management
3. Reduces noise intelligently - Without introducing artifacts
4. Balances dynamics - Compression settings for voice and music
5. Shapes tone - EQ adjustments for clarity and warmth

How to Use

Fix Audio Problems

My audio has [describe problem: too quiet, noisy background, inconsistent levels, muddy sound].
Help me fix it using proper processing order.

Prepare Audio for Platform

Help me prepare this audio for [podcast/YouTube/Spotify/broadcast].
Current state: [describe audio]

Master Audio Workflow

Create an audio editing workflow for [content type].
Include settings for [software: Audacity/Audition/etc.]

Instructions

When editing audio, follow this methodology:

Step 1: The Processing Order

Always process in this sequence to avoid compounding problems.

## Correct Processing Order

1. GAIN STAGING
   ↓
2. NOISE REDUCTION
   ↓
3. COMPRESSION
   ↓
4. EQUALIZATION
   ↓
5. FINAL NORMALIZATION / LIMITING

Why this order:
- Noise reduction BEFORE compression: Prevents amplifying noise
- Compression BEFORE EQ: Prevents EQ changes affecting dynamics
- Limiting LAST: Sets final ceiling after all processing

Step 2: Gain Staging

Set initial levels before any processing.

## Gain Staging Guidelines

**Recording (target during capture)**:
- Peaks at -12 to -6 dB
- Leaves headroom for processing

**Initial Normalization (start of editing)**:
- Normalize peaks to -6 dB
- Creates consistent starting point

**Two Types of Normalization**:

1. **Peak Normalization**
   - Adjusts based on loudest point
   - Use for: Initial gain staging
   - Does NOT change dynamic range

2. **RMS/Loudness Normalization**
   - Adjusts based on average level
   - Use for: Final delivery
   - Better for perceived loudness matching

Tool-Specific:

Step 3: Noise Reduction

Remove unwanted background sound without artifacts.

## Noise Reduction Approach

**When to use**:
- Consistent background hiss/hum
- Air conditioning, computer fan noise
- Not for variable noise (traffic, voices)

**Method 1: Spectral Noise Reduction**
1. Find 2-3 seconds of "silence" (noise only)
2. Use as noise profile
3. Apply reduction to full track
4. Use conservative settings

**Settings Guide** (Audacity example):
- Noise Reduction: 6-12 dB (start low)
- Sensitivity: 4-6 (higher = more aggressive)
- Frequency Smoothing: 3-6 bands

**Method 2: Noise Gate**
- Sets threshold; audio below is silenced
- Better for breaths between speech
- Doesn't affect audio during speech

**Warning Signs of Over-Processing**:
- "Underwater" or "robotic" sound
- Swirling artifacts
- Unnatural silence between words

**Rule**: If choosing between slight noise or artifacts, keep the noise.

Step 4: Compression

Even out dynamics—reduce loud parts, bring up quiet parts.

## Compression for Voice

**What It Does**:
- Reduces volume of sounds above threshold
- Results in more consistent, fuller sound

**Key Parameters**:

| Parameter | What It Does | Voice Setting |
|-----------|--------------|---------------|
| Threshold | Level where compression starts | -20 to -12 dB |
| Ratio | How much to reduce | 2:1 to 4:1 |
| Attack | How fast compression kicks in | 10-30 ms |
| Release | How fast compression stops | 100-300 ms |
| Makeup Gain | Boosts output after compression | To taste |

**Voice Compression Starting Point**:
- Threshold: -18 dB
- Ratio: 3:1
- Attack: 15 ms (fast enough for transients)
- Release: 150 ms
- Gain: +3-6 dB (compensate for reduction)

**Multi-Band Compression** (advanced):
- Different settings for different frequency ranges
- Useful for controlling low-end rumble without affecting highs
- Overkill for most marketing audio

**When NOT to Compress**:
- Already consistent audio (well-recorded)
- Music meant to be dynamic
- Over-compression sounds "squashed"

Step 5: Equalization (EQ)

Shape the tone—cut problems, enhance clarity.

## EQ for Voice

**Philosophy**: Cut more than boost. Removing problems is safer than adding "goodness."

**Voice Frequency Guide**:

| Range | Frequency | Effect |
|-------|-----------|--------|
| Rumble | Below 80 Hz | Cut (high-pass filter) |
| Muddiness | 200-400 Hz | Cut if boomy |
| Body/Warmth | 150-250 Hz | Boost slightly for thin voice |
| Boxy/Nasal | 400-800 Hz | Cut if honky |
| Clarity/Presence | 2-4 kHz | Boost for intelligibility |
| Sibilance | 5-8 kHz | Cut if harsh "s" sounds |
| Air/Brightness | 8-12 kHz | Boost for expensive studio feel |

**Standard Voice EQ Recipe**:
1. High-pass filter at 80 Hz (removes rumble)
2. Cut 2-3 dB around 300 Hz (reduces muddiness)
3. Boost 2-3 dB around 3 kHz (adds clarity)
4. High-shelf boost at 10 kHz if needed (adds air)

**De-essing**:
- Tames harsh "s" and "sh" sounds
- Target: 5-8 kHz range
- Use de-esser plugin OR narrow EQ cut

Step 6: Final Normalization / Limiting

Set output level for delivery platform.

## Loudness Standards by Platform

| Platform | Target | Measurement |
|----------|--------|-------------|
| Podcast (general) | -16 LUFS | Integrated loudness |
| Spotify/Apple Podcasts | -14 LUFS | May normalize further |
| YouTube | -14 LUFS | Recommended |
| Broadcast TV (US) | -24 LKFS | FCC regulation |
| ACX/Audiobooks | -23 to -18 dB RMS | Per chapter |

**Final Steps**:

1. **Loudness Normalization**
   - Match to platform standard (e.g., -16 LUFS)
   - Use loudness meter, not peak meter

2. **Limiting**
   - Prevents clipping
   - Set ceiling at -1 dB (leaves headroom for encoding)
   - Catches peaks that exceed ceiling

3. **Export Settings**
   - Podcast: 128-192 kbps MP3, stereo
   - Video: Match video project settings
   - Audiobook: 192 kbps MP3, 44.1 kHz, mono

Examples

Example 1: Fixing a Noisy Podcast Recording

Context: Recorded a remote podcast interview with audible background hum.

Input:

My podcast guest recorded on their laptop mic. There's a consistent low hum and the levels are all over the place—sometimes quiet, sometimes too loud. How do I fix this?

Output:

Podcast Rescue Workflow