Audiobook Production

Why This Matters: ACX/Audible rejects audiobooks that don't meet technical specifications, wasting production time and money. Beyond technical compliance, understanding how listeners process audio enables production choices that maximize engagement and retention.

What Claude Does vs What You Decide

What This Skill Does

1. Ensures ACX technical compliance - Specs for bit rate, sample rate, RMS, peaks, and noise floor
2. Structures audiobook projects - Chapter organization, credits, retail samples
3. Applies learning principles - Pacing, tone, and delivery that aid comprehension
4. Manages production workflow - From script to final master
5. Handles proofing and QC - Catching errors before submission

How to Use

Check ACX Compliance

Help me verify this audiobook meets ACX submission requirements.
[provide audio specs or describe setup]

Plan Audiobook Structure

Help me structure an audiobook from this manuscript:
Total word count: [X]
Chapters: [Y]
Type: [Fiction/Non-fiction]

Create Production Workflow

Create a production plan for my audiobook project:
Book length: [word count]
Narrator: [self/hired]
Deadline: [date]

Instructions

When producing audiobooks, follow this methodology:

Step 1: Understand ACX Technical Requirements

ACX has strict specifications that must be met for acceptance.

## ACX Audio Specifications (2026)

### File Format
- MP3, 192 kbps or higher (constant bit rate)
- 44.1 kHz sample rate
- Mono (single channel)

### Audio Levels
- RMS: -23dB to -18dB
- Peak values: -3dB maximum (no clipping)
- Noise floor: -60dB or lower

### File Naming
- Chapter files: [BookTitle]_[ChapterNumber].mp3
- Opening credits: [BookTitle]_Opening_Credits.mp3
- Closing credits: [BookTitle]_Closing_Credits.mp3

### Content Requirements
- Opening credits (first file): Title, author, narrator
- Closing credits (last file): "This has been [title] by [author], narrated by [narrator]"
- Each chapter file is standalone (no cross-file audio)
- Consistent room tone throughout

### Quality Requirements
- No extraneous sounds (mouth clicks, pops, page turns)
- Consistent audio quality across all files
- Retail sample: ~5 minutes of representative content

Critical: Run ACX Check tool on every file before submission.

Step 2: Prepare the Manuscript

Before recording, optimize the text for audio delivery.

## Manuscript Preparation Checklist

### Structure
□ Chapter breaks clearly marked
□ Section breaks identified (longer pause points)
□ Footnotes converted to in-text explanations or removed
□ Visual content (charts, tables) adapted for audio or noted for skip

### Pronunciation Guide
□ Character names with phonetic spelling
□ Foreign words and phrases
□ Technical terms and jargon
□ Place names and proper nouns
□ Acronyms expanded or spelled out

### Narrator Notes
□ Tone shifts marked
□ Character voice cues (if fiction)
□ Emphasis suggestions (minimal)
□ "As shown in Figure X" → adapted for audio
□ Author asides or commentary identified

### Timing Estimate
□ Word count per chapter
□ Total word count
□ Estimated runtime: words ÷ 9,300 = hours (approx)
   - 50,000 words ≈ 5-6 hours
   - 80,000 words ≈ 8-9 hours

Step 3: Set Up Recording Environment

Consistent, quality recording requires proper setup.

## Home Studio Essentials

### Minimum Equipment
- **Microphone**: USB condenser (AT2020, Blue Yeti) or XLR setup
- **Pop filter**: Essential for plosives
- **Mic stand**: Stable positioning
- **Headphones**: Closed-back, wired

### Room Treatment
- Record in smallest, most furnished room available
- Hang blankets on hard surfaces
- Use reflection filter behind mic
- Close windows, turn off HVAC
- Eliminate electronic hum (fridges, computers)

### Recording Software (DAW)
- Free: Audacity, GarageBand
- Professional: Adobe Audition, Reaper, Pro Tools
- ACX-specific: Hindenburg Pro (audiobook workflow)

### Test Recording Checklist
□ Record 30 seconds of room tone
□ Record test passage
□ Check RMS levels (-23 to -18 dB)
□ Check peak levels (below -3 dB)
□ Check noise floor (below -60 dB)
□ Listen for room echo or hum
□ Verify consistent mic positioning

Step 4: Apply Mayer's Multimedia Learning Principles

Science-backed techniques for engaging audio.

## Mayer's Principles for Audiobook Delivery

### Voice Principle
"People learn better from human voice than machine voice."
→ Warm, conversational delivery beats polished broadcast voice
→ Let personality come through
→ Avoid monotone "reading" voice

### Personalization Principle
"People learn better when words are conversational rather than formal."
→ Write/deliver as if talking to one person
→ Use "you" and "we"
→ Contractions are encouraged

### Segmenting Principle
"People learn better when content is in learner-paced segments."
→ Clear chapter breaks
→ Section pauses for complex material
→ Chapter summaries for dense non-fiction

### Redundancy Principle (for video/slides)
"People learn better from graphics and narration than graphics + narration + text."
→ For audiobooks: don't describe visual elements you can't show
→ Adapt visual content or acknowledge it's omitted

### Coherence Principle
"People learn better when extraneous material is excluded."
→ Cut verbal filler
→ Remove tangents that don't serve the chapter
→ Every word earns its place

Step 5: Production Workflow

Systematic process from script to master.

## Audiobook Production Pipeline

### Phase 1: Pre-Production (Week 1-2)
□ Manuscript finalized and proofread
□ Pronunciation guide complete
□ Chapter structure confirmed
□ Recording schedule created
□ Test recordings approved

### Phase 2: Recording (Weeks 2-6, varies by length)
□ Opening credits recorded first
□ Chapters recorded in order (usually)
□ Room tone captured each session
□ Daily backup of raw files
□ Notes logged for pickups needed

### Phase 3: Editing (Concurrent or following)
□ Remove mistakes and restart takes
□ Remove excessive breaths (keep natural ones)
□ Eliminate mouth clicks and pops
□ Smooth edits (crossfade)
□ Consistent pacing throughout

### Phase 4: Mastering
□ Noise reduction applied (light touch)
□ Compression for consistent levels
□ Limiting to prevent peaks
□ Final RMS check (-23 to -18 dB)
□ Export to ACX specs (192 kbps MP3, 44.1kHz, mono)

### Phase 5: Quality Control
□ Listen to every file start to finish
□ Check first/last 5 seconds of each file
□ Verify file naming convention
□ Run ACX Check or similar tool
□ Create retail sample (5 min)

Step 6: Credits and Sample

Specific requirements for opening, closing, and retail sample.

## Opening Credits Script
(Must be first audio file)

"[Book Title]"
Written by [Author Name]
Narrated by [Narrator Name]

[Optional: Publisher name]
[Optional: Copyright year]

---

## Closing Credits Script
(Must be last audio file)

"This has been [Book Title], written by [Author Name],
narrated by [Narrator Name]."

[Optional: "Visit [website] for more" or other approved callout]
[Optional: "Audiobook production by [producer]"]

---

## Retail Sample Guidelines

**Length**: Approximately 5 minutes
**Content**: Representative excerpt that hooks listeners
**Selection criteria**:
- Showcases narrator's ability
- Engages interest without major spoilers
- Demonstrates the book's voice/style
- Often from early chapters (context not required)

**Do NOT include**: Credits or chapter announcements in sample

Examples

Example 1: Self-Published Non-Fiction Audiobook

Context: An author is self-narrating their business book.

Input:

Help me plan audiobook production for my 55,000-word business book. I'm self-narrating. I have a Blue Yeti mic and record in my home office.

Output:

Production Plan: Business Book Audiobook

Project Specifications

• Word count: 55,000 words
• Estimated runtime: 5.5-6 hours
• Narrator: Author (self-narrated)
• Equipment: Blue Yeti USB mic (adequate for ACX)

Pre-Production (Days 1-3)

Manuscript Prep

• Review all 12 chapters for audio adaptation
• Convert/adapt 8 figures referenced in text
• Create pronunciation guide for industry terms
• Mark chapter breaks and section pauses
• Estimate 4,500 words/chapter average = ~29 min/chapter

Room Preparation

• Assess home office acoustics
• Add blanket on wall behind recording position
• Use closet with clothes as recording booth alternative
• Test recordings at 3 different times of day (HVAC, traffic noise)

Sample Script: "As shown in Figure 3" → "Here's how it works: imagine a funnel with three stages..."

Recording Schedule (Weeks 1-3)

Daily recording block: 2 hours max (voice fatigue) Target per session: 1.5-2 chapters (8,000 words) Total sessions needed: ~8-10

Schedule:

• Day 1: Opening credits + Chapter 1
• Day 2: Chapters 2-3
• Day 3: Chapters 4-5
• [continue pattern]
• Day 8: Chapter 12 + Closing credits
• Days 9-10: Pickups and problem sections

Session Ritual:

1. Hydrate 30 min before (room temp water)
2. Vocal warmup (5 min)
3. Record room tone (10 sec)
4. Test recording, check levels
5. Record chapter(s)
6. Log pickup notes

Post-Production (Week 4)

Editing workflow per chapter:

1. Import raw audio
2. Remove mistakes and alternate takes
3. Clean up breaths and mouth clicks
4. Apply light noise reduction
5. Normalize RMS to -20 dB
6. Check peaks (below -3 dB)
7. Export as MP3 (192 kbps, 44.1 kHz, mono)

File naming:

• BusinessBookTitle_Opening_Credits.mp3
• BusinessBookTitle_001.mp3
• BusinessBookTitle_002.mp3
• ...
• BusinessBookTitle_012.mp3
• BusinessBookTitle_Closing_Credits.mp3

Quality Control (Days 1-2)

• Listen through every file with checklist
• Run ACX Check on all files
• Create 5-minute retail sample from Chapter 2
• Verify consistent sound across all chapters
• Final review of opening/closing credits

Technical Settings

Recording:

• 44.1 kHz, 24-bit WAV (edit in high quality)
• Mono input
• Gain set for peaks at -12 dB

Export (ACX compliant):

• MP3, 192 kbps CBR
• 44.1 kHz
• Mono
• RMS: -20 dB (within -23 to -18)
• Peak: -3 dB max

Example 2: ACX Troubleshooting

Context: Audiobook files are being rejected by ACX.

Input:

My audiobook submission was rejected. ACX says "RMS levels out of spec" and "noise floor too high." How do I fix this?

Output:

ACX Rejection Fix: RMS and Noise Floor

Diagnosis

RMS out of spec: Your audio is either too quiet (below -23 dB) or too loud (above -18 dB)

Noise floor too high: Background hiss or hum is above -60 dB

Step-by-Step Fix

Fix 1: RMS Levels

In Audacity:

1. Select all audio (Ctrl+A)
2. Effect → Loudness Normalization
3. Set to: -20 dB RMS (middle of ACX range)
4. Apply

In Adobe Audition:

1. Select all
2. Effects → Amplitude → Match Loudness
3. Set Target Loudness to -20 LUFS
4. Process

Fix 2: Noise Floor

If noise is mild (just room tone):

1. Find 2-3 seconds of "silence" (room tone only)
2. Select it as noise profile
3. Apply noise reduction to full track
4. Use minimal settings (6-12 dB reduction) to avoid artifacts

In Audacity:

• Effect → Noise Reduction → Get Noise Profile
• Select all → Noise Reduction → 6-12 dB, 6 Sensitivity

If noise is significant:

• Re-record in quieter environment
• Use noise gate (removes sound below threshold)
• Consider iZotope RX for professional repair

Fix 3: Verify Peaks

After RMS adjustment, peaks may exceed -3 dB:

1. Effect → Limiter
2. Set ceiling to -3.0 dB
3. Apply

Verification Workflow

1. Make fixes to one chapter first
2. Run ACX Check plugin or online tool
3. Verify all specs pass:
   • RMS: -23 to -18 dB ✓
   • Peak: -3 dB or lower ✓
   • Noise floor: -60 dB or lower ✓
4. Apply same process to all files
5. Re-check each file before resubmitting

Prevention for Future

Recording checklist:

• Noise floor below -60 dB before recording
• Gain set so peaks hit -12 dB when speaking
• Room tone recorded each session
• Test file checked before full session

Checklists & Templates

ACX Pre-Submission Checklist

## Technical Compliance

□ All files are 192 kbps MP3, 44.1 kHz, mono
□ RMS levels between -23 and -18 dB
□ Peak values at or below -3 dB
□ Noise floor at or below -60 dB
□ No clipping or distortion
□ Consistent levels across all chapters

## File Structure

□ Opening credits file present
□ Closing credits file present
□ Files named correctly: [Title]_[Number].mp3
□ Chapter numbers are sequential
□ No missing chapters
□ Retail sample created (≈5 minutes)

## Content Quality

□ First/last 5 seconds of each file are clean (room tone or fade)
□ No extraneous sounds (clicks, pops, breaths)
□ No room echo or reverb issues
□ Consistent voice quality throughout
□ All pickups and corrections completed
□ Credits read correctly (title, author, narrator)

## Final Review

□ Listened to complete audiobook
□ Spot-checked transitions between chapters
□ Verified retail sample is representative
□ Cover art meets ACX specs (if applicable)
□ All metadata entered correctly

Production Schedule Template

## Audiobook Production Schedule

**Title**: ________________________________
**Word count**: ___________ | **Est. runtime**: ___________
**Narrator**: _____________________________
**Target completion**: ____________________

### Pre-Production: Week ___

| Task | Due | Done |
|------|-----|------|
| Manuscript finalized | | □ |
| Pronunciation guide | | □ |
| Room/equipment tested | | □ |
| Opening credits scripted | | □ |

### Recording: Weeks ___ - ___

| Session | Chapters | Words | Est. Time | Done |
|---------|----------|-------|-----------|------|
| 1 | Credits + Ch 1 | | | □ |
| 2 | Ch 2-3 | | | □ |
| 3 | Ch 4-5 | | | □ |
| ... | | | | □ |

### Post-Production: Week ___

| Task | Due | Done |
|------|-----|------|
| Editing complete | | □ |
| Mastering complete | | □ |
| ACX specs verified | | □ |
| QC listen-through | | □ |
| Retail sample created | | □ |

### Submission: ___________

Skill Boundaries

What This Skill Does Well

• Structuring audio production workflows
• Providing technical guidance
• Creating quality checklists
• Suggesting creative approaches

What This Skill Cannot Do

• Replace audio engineering expertise
• Make subjective creative decisions
• Access or edit audio files directly
• Guarantee commercial success

References

• ACX. "Audio Submission Requirements" - Official technical specifications
• Richard Mayer. "Multimedia Learning" (2009) - Scientific principles for audio learning
• iZotope. "Professional Voice Over Recording Tips" - Technical recording guidance
• Audacity Team. "Audacity Manual" - Free editing software

Related Skills

• voiceover-direction - Directing talent for quality delivery
• audio-editing - Post-production fundamentals
• voice-design - AI voice alternatives for narration
• transcription-to-content - Repurposing audiobook content

Skill Metadata (Internal Use)