The process of adjusting audio levels to meet standardized loudness targets – ensures consistent perceived volume across different content, preventing jarring volume changes between programs while complying with broadcast regulations and streaming platform specifications.
What is Loudness Normalization?
Loudness Normalization is the process of adjusting audio levels to achieve standardized loudness targets. It ensures consistent perceived loudness across different content and meets broadcast and streaming requirements.
Basic Principle
| Aspect | Description |
|---|---|
| Goal | Consistent Loudness |
| Measurement | LUFS/LKFS |
| Standard | ITU-R BS.1770 |
| Application | Broadcast, Streaming |
Why Normalization?
| Problem | Solution |
|---|---|
| Loudness War | Standardized Levels |
| Volume Jumps | Consistency |
| Viewer Comfort | No Re-adjustment |
| Compliance | Regulatory Requirements |
Units of Measurement
| Unit | Description |
|---|---|
| LUFS | Loudness Units Full Scale |
| LKFS | Loudness K-weighted Full Scale |
| dBTP | True Peak Level |
| LRA | Loudness Range |
Target Levels by Platform
| Platform | Integrated Loudness | True Peak |
|---|---|---|
| Netflix | -27 LKFS (±2) | -2 dBTP |
| Spotify | -14 LUFS | -1 dBTP |
| YouTube | -14 LUFS | -1 dBTP |
| Broadcast EU | -23 LUFS (±1) | -1 dBTP |
Broadcast Standards
| Region | Standard | Target Level |
|---|---|---|
| Europe | EBU R128 | -23 LUFS |
| USA | ATSC A/85 | -24 LKFS |
| Japan | ARIB TR-B32 | -24 LKFS |
| International | ITU-R BS.1770 | Basis |
Measurement Types
| Type | Description |
|---|---|
| Momentary | 400ms Window |
| Short-term | 3 Second Window |
| Integrated | Overall Program |
| True Peak | Maximum Level |
Normalization Methods
| Method | Description |
|---|---|
| Gain Adjustment | Simple Level Change |
| Limiting | Peak Control |
| Compression | Reduce Dynamics |
| Hybrid | Combination |
Workflow
| Step | Description |
|---|---|
| 1 | Measure current loudness |
| 2 | Calculate difference to target |
| 3 | Adjust gain |
| 4 | Check True Peak |
Software Tools
| Tool | Function |
|---|---|
| WLM Plus | Waves Loudness Meter |
| Nugen Audio | Loudness Tools |
| iZotope RX | Loudness Control |
| Youlean | Free Loudness Meter |
DAW Integration
| DAW | Solution |
|---|---|
| Pro Tools | Integrated Meters |
| Nuendo | Supervision |
| DaVinci Resolve | Fairlight |
| Premiere Pro | Essential Sound |
True Peak Limiting
| Aspect | Description |
|---|---|
| Purpose | Catch Inter-Sample Peaks |
| Oversampling | 4x or higher |
| Headroom | For Codec Encoding |
| Target | -1 to -2 dBTP |
Loudness Range (LRA)
| Value | Description |
|---|---|
| Low (<5 LU) | Highly Compressed |
| Medium (5-10 LU) | Pop, Rock |
| High (>10 LU) | Classical, Film |
| Very High (>20 LU) | Uncompressed |
Streaming Normalization
| Platform | Method |
|---|---|
| Spotify | Normalize Down |
| Apple Music | Sound Check |
| YouTube | Automatic |
| Tidal | Normalize |
Avoiding Problems
| Problem | Solution |
|---|---|
| Too Quiet | Utilize Headroom |
| Too Loud | Employ Limiter |
| True Peak Over | Brickwall Limiter |
| Inconsistent | Re-check |
Cinema vs. Broadcast
| Aspect | Cinema | Broadcast |
|---|---|---|
| Reference | 85 dB SPL | Variable |
| Dynamics | Higher | Reduced |
| Standard | Dolby | EBU R128 |
| Loudness | Dialogue-Based | Integrated |
Dialogue Normalization
| Aspect | Description |
|---|---|
| Dialnorm | Dolby Metadata |
| Measurement | Dialogue Level |
| Adjustment | Decoder Adapts |
| Broadcast | Standard in AC-3 |
Quality Control
| Check | Criterion |
|---|---|
| Integrated | Within Tolerance |
| True Peak | Below Maximum |
| LRA | Appropriate |
| Dialogue | Intelligible |
Automatic vs. Manual
| Aspect | Automatic | Manual |
|---|---|---|
| Speed | Fast | Slow |
| Precision | Good | Better |
| Creativity | None | Possible |
| Consistency | High | Variable |
Best Practices
| Practice | Reason |
|---|---|
| Measure Early | Identify Issues |
| Observe True Peak | Codec Headroom |
| Check LRA | Preserve Dynamics |
| Documentation | For QC |
Today
Loudness Normalization is indispensable in modern audio post-production. With the introduction of standards like EBU R128 and ATSC A/85, the "Loudness War" has ended in professional environments. Streaming platforms normalize automatically, meaning excessively loud mixes no longer provide an advantage – on the contrary, they often sound worse after normalization.