Dynamic Processing

Question 1

What is compression in audio processing?

Answer 1

– Reduces the dynamic range of a signal by lowering the volume of sounds above a threshold and optionally boosting the overall level with make-up gain.
– Makes tracks sound more even in volume.

Question 2

How does a compressor work in two stages?

Answer 2

1. Reduces peaks above the threshold.
2. Raises the overall signal using make-up gain to restore perceived loudness.

Question 3

What can extreme compression cause?

Answer 3

– Ducking effect, overemphasis of quiet sounds like breaths, unnatural pumping.

Question 4

What is a de-esser?

Answer 4

– Reduces or removes sibilance by compressing only the sibilant frequency range via a sidechain.

Question 5

What is sidechain compression?

Answer 5

– Compression is triggered by the volume of one track but applied to another.
– Used for effects like ducking or de-essing.

Question 6

What is a limiter?

Answer 6

– A compressor with an extreme ratio (∞:1) that prevents a signal from exceeding a set level.

Question 7

Define threshold in compression.

Answer 7

– The volume above which compression starts.
– Low threshold = more compression; high threshold = less compression.

Question 8

Define ratio in compression.

Answer 8

– Determines the amount of gain reduction above the threshold (input:output).
– High ratio = more compression; low ratio = less.

Question 9

What is attack time in compression?

Answer 9

– How quickly compression is applied after the signal exceeds the threshold.
– Fast attack = reduces initial transient; slow attack = preserves transient.

Question 10

What is release time in compression?

Answer 10

– Time it takes for the compressor to stop compressing after the signal drops below the threshold.
– Short release = more sustain; long release = less sustain.

Question 11

Difference between Peak and RMS detection in compressors

Answer 11

– Peak: reacts to instantaneous amplitude; catches fast transients.
– RMS (Root Mean Square): based on average signal level; misses sudden peaks, sounds more natural.

Question 12

What is gating in audio processing?

Answer 12

– Silences signals below a threshold.
– Removes unwanted noise or quiet sounds between phrases.

Question 13

How does a gate work?

Answer 13

– Opens when signal exceeds threshold, closes below threshold.
– Reduces or mutes quiet parts without affecting louder sounds.

Question 14

What is a range/reduction control in a gate?

Answer 14

– Sets the amount of volume reduction.
– In a gate, this is often total silence; in an expander, partial reduction.

Question 15

Key timing controls in a gate

Answer 15

– Attack: time to open gate once above threshold.
– Hold: time gate stays open after signal drops below threshold.
– Release: time to close gate after hold ends.

Question 16

What is lookahead in gating?

Answer 16

– Allows the gate to analyse the incoming signal slightly ahead of time to avoid cutting off peaks prematurely.

Question 17

What is hysteresis in gating?

Answer 17

– Sets separate upper and lower thresholds to prevent chattering (rapid opening/closing)

Question 18

What is a keyed or sidechain gate?

Answer 18

– Gate or expander is triggered by a different signal via a sidechain input.

Question 19

What is perceived loudness?

Answer 19

– How loud a sound seems to the human ear, not just the measured amplitude.

Question 20

What are the “loudness wars”?

Answer 20

– Trend of making recordings louder with more compression, reducing dynamic range.
– Began in the 1990s, peaked around 2005.

Question 21

What are the negative effects of over-compression and loudness wars?

Answer 21

– Loss of detail, warmth, and dynamic range.
– Sounds distorted, flat, and fatiguing to listeners.

Question 22

What is LUFS?

Answer 22

– Loudness Units relative to Full Scale.
– Measures perceived loudness compared to maximum digital level (0 dBFS).
– Used by streaming services for loudness normalisation.

Question 23

How does compression impact percussive sounds?

Answer 23

– Adds impact and punch.
– Simplifies mixing by making levels more consistent.

Question 24

How does compression affect perceived loudness?

Answer 24

– Reduces dynamic range, allowing overall volume to be raised.
– Creates a more consistently loud track.

Question 25

How can gating be used creatively?

Answer 25

– Removes unwanted noise, amp hiss, or ambient sounds. – Helps clean up recordings automatically between phrases.

Question 26

What are potential drawbacks of overusing dynamics processing?

Answer 26

– Lack of dynamic range, increased masking, reduced clarity. – Listener fatigue due to constant loudness. – Encourages a “perfectionist” approach, reducing musical expressiveness.

Question 27

What is “pumping” in compression?

Answer 27

– Musical effect where compression rhythmically lowers volume, often used in EDM for impact.

Question 28

What is a VCA (Voltage Controlled Amplifier) compressor?

Answer 28

– Uses a voltage-controlled gain circuit to reduce signal level. – Known for fast attack and precise control. – Common in drum buses and full mixes. – Example: SSL G-Series Bus Compressor.

Question 29

What is an FET (Field Effect Transistor) compressor?

Answer 29

– Uses transistor circuits to reduce gain. – Known for fast, punchy response and characterful distortion. – Great for drums, percussion, and aggressive vocals. – Example: UREI 1176.

Question 30

What is an Optical (Opto) compressor?

Answer 30

– Uses a light source and photocell to control gain reduction. – Smooth, musical compression with slower attack and release. – Good for vocals, bass, and instruments needing natural dynamics. – Example: LA-2A.

Question 31

What is a Vari-Mu (Tube) compressor?

Answer 31

– Tube-based compression where gain reduction varies with input level. – Adds warmth and saturation to the sound. – Ideal for mastering, vocals, or mix buses. – Example: Fairchild 670.

Question 32

What is multiband compression?

Answer 32

– Splits the signal into frequency bands and compresses each separately. – Useful for controlling problematic frequencies without affecting the whole mix. – Common in mastering, broadcast, or vocals.

Question 33

What is parallel (New York) compression?

Answer 33

– Blends a heavily compressed signal with the dry signal. – Maintains natural dynamics while adding punch and density. – Often used on drums, bass, or vocals.

Question 34

What is sidechain compression and its effect?

Answer 34

– Compression on one track triggered by another. – Creates rhythmic ducking (e.g., kick drum lowering bass). – Can control sibilance or highlight other instruments.

Question 35

What is limiting in practice?

Answer 35

– Extreme compression (∞:1 ratio). – Prevents peaks from exceeding a set level. – Used in mastering or to avoid digital clipping. – Example: Waves L2, FabFilter Pro-L.

Question 36

How does compressor type affect the sound character?

Answer 36

– VCA: precise, punchy. – FET: aggressive, fast, edgy. – Opto: smooth, warm, natural. – Tube/Vari-Mu: warm, rounded, musical saturation.

Question 37

When would you choose an Opto compressor over a VCA?

Answer 37

– For smooth, musical compression on vocals or bass. – When you want gentle dynamic control without transient squashing.

Question 38

Example usage: 1176 FET

Answer 38

– Compressing snare, drums, aggressive vocals. – Creates punch, presence, and controlled peaks.

Question 39

Example usage: LA-2A Opto

Answer 39

– Compressing lead vocals, bass, and instruments needing smooth dynamics. – Adds warmth and natural sustain.

Question 40

Example usage: SSL Bus Compressor

Answer 40

– Compressing full mix or drum bus. – Adds glue and cohesion while preserving punch.

Question 41

Practical tip for parallel compression

Answer 41

– Send the track to an auxiliary bus, compress heavily, then blend back with the dry signal to maintain dynamics but add body.

Question 42

Why use multiband compression?

Answer 42

– Controls specific frequency ranges (e.g., tame bass without affecting highs). – Avoids global squashing of the mix.