Far Field / Reverberant Field / Diffuse Field

near field fast fourier transform fft high fidelity

Acoustic region where reflected sound dominates over direct sound from the source – characterized by uniform sound pressure level regardless of distance, important for understanding room acoustics and microphone placement in film production.

What is Far Field?

The Far Field is the acoustic area where reflected sound dominates over direct sound. Here, the sound level no longer decreases significantly with distance – room acoustics determine the sound.

Near Field vs. Far Field

Aspect	Near Field	Far Field
Dominance	Direct Sound	Reflections
Distance Law	Applies	Does Not Apply
Sound Character	Dry	Reverberant
Sense of Space	Minimal	Strong

Critical Distance

Element	Description
Definition	Boundary Near/Far Field
Position	Direct = Reflected
Calculation	Room Dependent
Significance	Microphone Decision

Acoustic Characteristics

Characteristic	Far Field
SPL	Relatively Constant
Frequency	Room Dependent
Directionality	Diffuse
Coherence	Low

Far Field in Film Production

Situation	Impact
Dialogue	More space in the sound
Atmosphere	Environmental character
Music	Spatial depth
Effects	Realistic distance

Microphone Placement

Position	Sound Character
Near Field	Direct, dry
Transition Zone	Mixed
Far Field	Spacious, reverberant

Room Types and Far Field

Room	Far-Field Start
Treated Studio	Far
Normal Room	~1-3 m
Church/Hall	Very close
Outdoors	Practically none

Dialogue Recording

Strategy	Description
Prefer Proximity	Utilize Near Field
Shotgun Microphone	Room Suppression
Lavalier	On the Body
Boom	Position Optimally

Atmosphere Recording

Application	Technique
Room Tone	Far-Field Microphones
Ambience	Omnidirectional
Stereo	Pair in the Room
Surround	Multiple Positions

Frequency Response

Frequency	Far-Field Characteristic
Low Frequency	Builds Up
Mid Frequency	Room Resonance
High Frequency	Absorption

Mixing Perspective

Element	Usage
Dialogue	Near Field Preferred
Music	Far Field for Depth
SFX	Depending on Distance
Reverb	Simulated Far Field

Problems in the Far Field

Problem	Solution
Too Much Reverb	Closer Miking
Lack of Intelligibility	Use Absorbers
Inconsistency	Room Treatment
Comb Filtering	Change Position

Far-Field Monitoring

Application	Description
Studio Monitors	Far-Field Speakers
Distance	From ~2 m
Room Influence	Considered
Calibration	Critical

Formula: Critical Distance

Variable	Meaning
Dc	Critical Distance
V	Room Volume
RT60	Reverberation Time
Q	Directivity Factor

Set Acoustics

Measure	Effect
Absorbers	Reduce Far Field
Diffusers	More Uniform
Sound Blankets	Dampen Reflections
Microphone Choice	Right for the Room

Best Practices

Practice	Reason
Understand the Room	Know the Far-Field Position
Microphone Selection	Matching the Room
Test Placement	Before Recording
Document	For Continuity

Today

Understanding far-field acoustics remains fundamental for audio professionals. Whether in dialogue recording, music recording, or atmosphere capture – knowledge of the transition from direct to reflected sound determines the quality of every audio recording.

From the crafts

Perspectives

Cinematographer

Far-Field-Akustik beeinflusst, wo der Tonmeister das Mikrofon platziert. Bei halligen Räumen muss ich Kompromisse bei der Kameraposition eingehen – oder wir nutzen ADR.

Director

Im Far Field klingt alles 'roomy' – manchmal gewollt für Atmosphäre, manchmal problematisch für Dialog. Die Tonentscheidung beeinflusst die emotionale Wirkung meiner Szenen.

Producer

Far-Field-Probleme am Set bedeuten oft ADR in der Post. Das kostet extra – bessere Akustik-Kontrolle vor Ort ist oft günstiger als Nachsynchronisation.