The subjective perception of audio volume as experienced by the human ear – measured using standardized algorithms (LUFS/LKFS) that approximate human hearing, distinct from simple peak or RMS measurements, and essential for broadcast compliance and consistent listening experiences.
What is Loudness?
Loudness is the subjective perception of audio volume by the human ear. It differs from technical level measurements because it accounts for how humans actually perceive sound.
Basic Principles
| Aspect | Description |
|---|---|
| Definition | Perceived loudness |
| Measurement | LUFS/LKFS |
| Basis | Psychoacoustics |
| Difference from | Peak, RMS |
Loudness vs. Peak
| Aspect | Loudness | Peak |
|---|---|---|
| Measures | Perception | Maximum value |
| Timeframe | Integrated | Instantaneous |
| Frequency Weighting | Yes (K-Weighting) | No |
| Relevance | Listening experience | Clipping |
Psychoacoustic Fundamentals
| Phenomenon | Description |
|---|---|
| Fletcher-Munson | Frequency-dependent perception |
| Temporal Integration | Short-term vs. Long-term |
| Masking | Loud sounds cover quiet tones |
| Dynamics | Perception of contrasts |
Measurement Algorithms
| Standard | Description |
|---|---|
| ITU-R BS.1770 | International standard |
| K-Weighting | Frequency curve |
| Gating | Excluding silence |
| True Peak | Inter-sample peaks |
K-Weighting
| Frequency Range | Influence |
|---|---|
| Deep Bass (<100Hz) | Reduced |
| Bass (100-500Hz) | Slightly reduced |
| Mids (500-4kHz) | Neutral |
| Highs (>4kHz) | Slightly boosted |
Measurement Types
| Type | Time Window | Application |
|---|---|---|
| Momentary (M) | 400ms | Current loudness |
| Short-term (S) | 3s | Short passages |
| Integrated (I) | Overall | Program loudness |
Loudness Units
| Unit | Description |
|---|---|
| LUFS | Loudness Units Full Scale |
| LKFS | Loudness K-weighted Full Scale |
| LU | Loudness Unit (relative) |
| dBTP | True Peak |
Target Values
| Application | Target Loudness |
|---|---|
| Broadcast TV | -24 LKFS |
| Streaming | -14 LUFS |
| Cinema | Dialogue-based |
| Podcast | -16 to -19 LUFS |
Loudness Range (LRA)
| Range | Description | Example |
|---|---|---|
| <5 LU | Very compressed | Pop mastering |
| 5-10 LU | Moderate | Rock, Pop |
| 10-20 LU | Dynamic | Film |
| >20 LU | Very dynamic | Classical |
Measurement Tools
| Tool | Type |
|---|---|
| WLM Plus | Plugin |
| Youlean Loudness Meter | Free Plugin |
| Nugen VisLM | Professional |
| iZotope Insight | Suite |
Gating
| Type | Threshold | Function |
|---|---|---|
| Absolute Gate | -70 LUFS | Ignore silence |
| Relative Gate | -10 LU | Quiet passages |
| Combination | Both | Standard ITU |
Practical Application
| Step | Description |
|---|---|
| 1 | Create mix |
| 2 | Measure loudness |
| 3 | Adjust gain |
| 4 | Check True Peak |
Loudness War
| Aspect | Description |
|---|---|
| Problem | Mastering louder and louder |
| Consequence | Loss of dynamics |
| Solution | Normalization standards |
| Today | Standards end the war |
Streaming Normalization
| Platform | Method |
|---|---|
| Spotify | -14 LUFS Target |
| YouTube | -14 LUFS Target |
| Apple Music | -16 LUFS |
| Tidal | Variable |
Cinema Context
| Aspect | Description |
|---|---|
| Reference | 85 dB SPL |
| Dialogue | -31 LKFS |
| Dynamics | High range |
| Measurement | Dialogue-based |
Dialogue Loudness
| Parameter | Description |
|---|---|
| Anchor | Dialogue as reference |
| Intelligibility | Clarity |
| Balance | With music/SFX |
| Consistency | Across scenes |
Common Mistakes
| Mistake | Solution |
|---|---|
| Too loud | Will be normalized down |
| Too quiet | Wasted headroom |
| Inconsistent | Automatic adjustment difficult |
| True Peak Over | Use a limiter |
Best Practices
| Practice | Reason |
|---|---|
| Measure early | Identify problems |
| Know the target value | Platform-specific |
| Preserve dynamics | Musicality |
| Consider True Peak | Codec headroom |
Today
Loudness management has become standard in professional audio production. With the introduction of EBU R128 and ATSC A/85, there are clear guidelines that improve the viewer experience. Streaming platforms normalize automatically, meaning overly compressed, loud mixes no longer have a competitive advantage – good sound wins over pure level.