Non-Diegetic Sound

Technical Fundamentals

Non-Diegetic Sound (also "extradiegetic" or "non-diegetic sound") is any audio element that does not originate from within the film's world and cannot be heard by the characters. This is a pure filmmaking tool for the audience.

Classic Examples of Non-Diegetic Sound

1. Film Score (orchestral music, strings, brass)
2. Voice-Over Narration (character speaking to the audience or inner thoughts)
3. Dramatic Sound Effects (exaggerated explosions, "whoosh" transitions)
4. Music for Transition/Montage (not within the film's space, only for the audience)
5. Emotional Music Stabs (sudden aggressive music during a jump scare)
6. Ambient Music Mood (not locatable within the space)

Difference: Diegetic vs. Non-Diegetic

Test: Is This Sound Diegetic or Not?

Question: "Would the characters in the film hear this sound if they were listening?"

• YES = Diegetic
• NO = Non-Diegetic

Examples:

• Music from a radio: "Would the character hear it?" YES → Diegetic
• Orchestral score during a scene: "Would the character hear it?" NO → Non-Diegetic
• Dialogue between actors: "Would the character hear it?" YES → Diegetic
• Voice-over narration: "Would the character hear these inner thoughts?" NO → Non-Diegetic

Technical Treatment of Non-Diegetic Sound

1. Lack of Room Acoustics

Non-diegetic sound has no room acoustics (or very minimal):

• Diegetic Radio: Sounds like a radio with room reverb and absorption
• Non-Diegetic Score: Sounds like "music in the head" – stereo, no spatial positioning, no room reverb

Practical Implementation:

• Non-diegetic music is recorded with minimal or zero reverb
• Or: With universal reverb (e.g., plate reverb), not room-specific reverb

2. Stereo Presentation

Non-diegetic sound is typically stereo or mono, not spatially positioned:

Score Example:

• Strings: Wide stereo presentation (left-right width)
• Brass: Center or slightly wide stereo
• Bass/Drums: Center or subwoofer (no left-right difference)

This differs from diegetic sound, which is spatially positioned (left for outside window, right for inside door, etc.).

3. Volume Independent of Distance

Non-diegetic sound does not change in volume based on character distance:

Scenario:

• Character walks from foreground to background
• Diegetic sound (footsteps): Gets quieter (the further away, the quieter)
• Non-diegetic music: Stays the same volume (it's "above" the scene, not in the scene)

This makes non-diegetic music "timeless" – it doesn't fluctuate like real sources.

4. Frequency Response: No Filter by Distance

Non-diegetic sound is not low-pass filtered based on distance:

Scenario:

• Diegetic sound (distant voice): Reduced high frequencies, muffled (simulates air absorption)
• Non-diegetic sound (score): Full frequency response, brilliant (not filtered by "air")

This preserves the emotional presence of non-diegetic sound.

Practical Applications of Non-Diegetic Sound

1. Film Score (Film Composer)

Definition:

Non-diegetic music, composed and orchestrated for film scenes.

Examples:

• Epic string music for heroic moments
• Subtle piano music for emotional scenes
• Aggressive brass for action moments

Technical Treatment:

1. Recording: Orchestra is recorded in a sound studio (typically 24-bit, 48 kHz)
2. Mixing: Composer/mixing engineer balances instruments:

• Cellos/Bass: Deep emotional foundation
• Violins: Melodic beauty
• Brass: Aggression/Dominance
• Drums: Rhythmic drivers (often subtle)

1. Mixing for Film:

• Wide stereo presentation
• Normalized to -18 LUFS (audio standard for music)
• Peak volume controlled (-2 dBFS maximum)

2. Voice-Over Narration

Definition:

Non-diegetic dialogue where a character speaks to the audience or expresses inner thoughts.

Examples:

• "This was the beginning of my greatest adventure..." (character speaking to audience)
• "I didn't know this would be the last day..." (character's inner thoughts)

Technical Treatment:

1. Recording: Actor is recorded in an ADR studio
2. Characterization: Voice often sounds:

• Deeper/more intimate than normal dialogue
• With lower energy (inner thoughts sound quieter)
• Sometimes temporally delayed (contemplative tone)

1. Mixing:

• No room acoustics (voice-over is "universal")
• Slight compression for consistency
• Optional: Reverb (subtle, not room reverb, more plate or hall for "sheen")

3. Jump Scare Sound Design

Definition:

Dramatic, often non-realistic sound effects to startle the audience.

Examples:

• Stab Sound: Suddenly aggressive orchestral music (very loud, aggressive dissonances)
• Horror Chimes: Synthetic, exaggerated noises (not from the real world)
• Whoosh Transitions: Dramatic sound effects between scenes

Technical Treatment:

1. Stab Component:

• Very fast attack (< 50 ms, immediate loudness)
• Aggressive frequencies (often 1-4 kHz for attention, plus 8+ kHz for aggression)
• Short duration (200-800 ms) for maximum shock effect
• Short decay (quickly fading music)

1. Example Frequency Content:

• 60 Hz: Low bass (feels like danger)
• 1-2 kHz: Presence (attention)
• 4-8 kHz: Aggression (sharp, unpleasant)
• 12+ kHz: Sibilance (high, piercing scream-like)

1. Mixing for Maximum Fear:

• Levels often at -2 to -1 dBFS (very loud, but not clipping)
• Pan: Often center to evoke a universal reaction
• Reverb: NO (should feel direct and immediate)

4. Ambient/Mood Music (Music Stingers)

Definition:

Subtle non-diegetic music for emotional coloring without a dominant melody.

Examples:

• Drones (constant tones for tension)
• Pads (emotional harmonic textures)
• Atonal/Ambient (no clear melody, just mood)

Technical Treatment:

1. Recording: Synthetically or acoustically recorded
2. Characterization:

• Subtle, not melodic
• Continuous or slowly evolving
• Little dynamic fluctuation

1. Mixing:

• Wide stereo
• Moderate reverb for "sense of space" (but not room-specific)
• Often -15 to -20 dBFS below dialogue for subtlety

Common Mistakes with Non-Diegetic Sound

Mixing Practice: Level Balancing

Standard Levels for Non-Diegetic Material

In a typical film mix:

Dynamic Mixing

Non-diegetic music is typically not mixed statically, but dynamically adjusted:

Scene Example:

• Dialogue: Score below -12 dB (very subtle)
• Pause after Dialogue: Score comes up to -6 dB (more focus)
• Action/Drama: Score at -3 dB (almost level with dialogue)

This creates a narrative dynamic where the score varies the emotional intensity.

Summary

Non-diegetic sound is the filmmaker's creative and emotional tool. While diegetic sound is the "reality" of the film, non-diegetic sound is the "emotional manipulation."

Best Practice:

• Score: Subtle and supportive, not dominant
• Voice-Over: Clear and understandable, emotionally present
• Sound Design Effects: Dramatic and impactful for shock/drama
• Balancing: Score should not overpower dialogue and Foley

A great film like "Inception" or "Interstellar" gets its emotional power not just from visual storytelling and acting, but from non-diegetic music and sound design that support and enhance the visual story.

Without non-diegetic sound, a film would feel like a documentary video. With great non-diegetic music and sound design, it becomes cinema.