{"course":{"slug":"motion-and-audio","title":"Motion, Sound and Music","url":"https://addaly.com/learn/motion-and-audio","level":"intermediate","track":"create"},"lesson":{"slug":"turning-the-loud-bits-down","title":"Compression does not make anything louder","url":"https://addaly.com/learn/motion-and-audio/turning-the-loud-bits-down","position":56,"of":72,"minutes":11,"answer":"A compressor only turns loud parts down; the make-up gain afterwards is what raises everything, including whatever noise sits in the gaps.","keyIdea":"A compressor only turns loud parts down; the make-up gain afterwards is what raises everything, including whatever noise sits in the gaps."},"body":{"format":"markdown","text":"## Compression does not make anything louder\n\nA compressor turns down anything above a threshold. That is the entirety of what it does. It has no mechanism for making sound louder.\n\nWhat makes it louder is the make-up gain you add afterwards. Once the peaks have been pulled down, there is headroom, so you can raise the whole signal, and the quiet parts come up with it. Hence the only description of compression worth memorising: **turning the loud bits down so the quiet bits can come up.**\n\nUnderstanding that changes how you set it, and it explains the failure mode at the end of this lesson.\n\n## Do it in this order\n\nClean the performance, then fix the tone, then control the dynamics, then set the loudness. In that order.\n\nOut of order, the compressor reacts to noise you are about to remove, and your EQ shapes a signal you are about to change. People who cannot get a voice to sit right are usually sequencing wrong rather than doing any one step wrong.\n\n### Editing the performance\n\nCut the false starts, the long pauses and the ums. Do not cut every breath. A voice with no breaths sounds inhuman, and breaths mark where sentences begin and end: remove them all and listeners lose the structure of what you said. Reduce a distracting breath by 6 to 10 dB instead of deleting it.\n\nTwo mechanical points that account for most audible edits:\n\n- Place a cut at a zero crossing, or put a 5 to 10 ms crossfade over it. Cutting through the middle of a waveform leaves a step, and a step is a click. Most editors handle this; Audacity does not always.\n- Cut immediately after a hard consonant (a t, k or p) where the seam hides. Cutting in the middle of a vowel is audible even when the timing is right.\n\nThen lay your room tone under the whole track. Silence between edited phrases sounds like the audio has dropped out. Continuous room tone is what makes heavily edited speech sound like one take.\n\n### EQ in three moves\n\n1. **High-pass filter.** Around 80 Hz for a deep voice, 100 to 120 Hz for a higher one. Below that there is rumble, air conditioning, traffic and desk thumps, and no speech at all. Sweep it upward until the voice starts to thin, then come back a little.\n2. **Cut, do not boost, between 200 and 500 Hz** if the voice sounds boxy, boomy or muddy. Two to four decibels with a fairly wide bandwidth. This is where a small untreated room lives.\n3. **A gentle lift of 2 to 3 dB between 3 and 6 kHz** for clarity. If that makes the s sounds harsh, use a de-esser around 5 to 8 kHz rather than a static cut, which dulls the whole voice to fix a few moments.\n\nThe general rule: cuts are forgiving, boosts are not. If you find yourself boosting more than about 4 dB anywhere, the answer is at the recording end.\n\n### Setting a compressor\n\nA workable starting point for speech:\n\n- Ratio 3:1.\n- Threshold set so the loudest phrases show 3 to 6 dB of gain reduction on the meter, and the quiet phrases show none.\n- Attack around 10 ms. Fast enough to catch the peaks, slow enough to let the consonant transients through. A very fast attack dulls speech and is a common cause of a voice that sounds oddly soft.\n- Release 100 to 200 ms, or auto.\n- Make-up gain until the compressed version matches the uncompressed version in perceived level, so you are judging the sound and not just the volume.\n\n**The failure mode.** If the background hiss rises and falls between sentences, you are over-compressing. During speech the compressor is pulling the level down; in the gap there is nothing above the threshold, so nothing is being pulled down, and the full make-up gain lands on the room noise. That swelling and receding is the sound of too much gain reduction. Back it off, or gate gently, or fix the noise floor at the source.\n\n## De-noising\n\nIt works by learning a profile of a steady sound and subtracting it in the frequency domain. So it handles hum, fans and hiss well, and anything that varies badly.\n\nPush it hard and you get the characteristic artefacts: an underwater quality, and small warbling tones sometimes called birdies, which appear where the subtraction has removed most but not all of a frequency band. Six to ten decibels of reduction is usually inaudible. Twenty is usually obvious.\n\nTake the least you can live with. A slightly hissy voice is far easier to listen to for ten minutes than a clean one that warbles.\n\n## Loudness, and why louder is pointless\n\nStreaming platforms normalise. Push your file louder than roughly −14 LUFS and YouTube or Spotify will turn it back down, and all you have achieved is a squashed, airless dynamic range that arrives at the listener at the same volume as everyone else's.\n\nAim for around −14 LUFS integrated for video platforms, around −16 LUFS for podcasts, with true peak no higher than −1 dBTP. Free ways to measure: Resolve's Fairlight page has a loudness meter, ffmpeg's `loudnorm` filter measures and applies, and Youlean's free loudness meter plugin works in most hosts.\n\n## The free toolkit, and ten seconds today\n\n- **Audacity**: free and open source, does every step above, including a usable noise reduction.\n- **DaVinci Resolve, Fairlight page**: free, a proper mixer with compression, EQ, metering and a ducker.\n- **Reaper**: an evaluation that never expires and a personal licence around $60, as of 2025.\n- **Ocenaudio**, **Ardour**, **Cakewalk** on Windows: all free or near enough. On a phone, **CapCut**'s audio enhancement is fine for speech.\n\n### Ten seconds today\n\nTake one minute of your voice, apply a high-pass filter at 100 Hz, and A/B it. That one control is usually the largest single improvement available to you."},"check":{"question":"After compressing a voiceover fairly hard, an editor notices the background hiss swelling up between sentences and receding when the person speaks. What is happening?","options":[{"text":"The noise reduction was applied after the compressor and is mistracking the changing signal.","correct":false,"tempting":"Blames processing order for a level fluctuation the compressor produces on its own."},{"text":"The release time is too long, so the compressor is holding the gain down into the following phrase.","correct":false,"tempting":"Has the direction reversed: a long release keeps the noise pushed down rather than letting it rise."},{"text":"The high-pass filter is set too low and is letting low-frequency rumble through in the quiet passages.","correct":false,"tempting":"Treats an audible change in level as a frequency-balance problem."},{"text":"During speech the compressor pulls the level down, but in the gaps nothing exceeds the threshold, so the full make-up gain lands on the room noise. There is too much gain reduction.","correct":true}]},"prev":{"slug":"eq-in-three-moves","title":"Three EQ moves that cover most voices","url":"https://addaly.com/learn/motion-and-audio/eq-in-three-moves"},"next":{"slug":"de-essing-and-plosives","title":"Wind, hiss, and why both are placement problems","url":"https://addaly.com/learn/motion-and-audio/de-essing-and-plosives"},"authorship":"Founder and series editor: Dr Mustafa Mun. Written by AI models to a written standard. Exam keys checked blind by a second model: 3,665 of 3,666 agreed. Academic review invited.","review":{"status":"Draft, open for academic review"},"cite":"Addaly (2026) 'Compression does not make anything louder', in Motion, Sound and Music. Edited by M. Mun. Addaly. Available at: https://addaly.com/learn/motion-and-audio/turning-the-loud-bits-down (Accessed: 31 October 2026).","licence":{"name":"CC BY-NC-SA 4.0","url":"https://creativecommons.org/licenses/by-nc-sa/4.0/"},"reader":{"schema":1,"title":"Compression does not make anything louder","courseTitle":"Motion, Sound and Music","module":{"index":7,"slug":"shaping-and-mixing-sound","title":"Shaping and mixing sound"},"answer":null,"keyIdea":"A compressor only turns loud parts down; the make-up gain afterwards is what raises everything, including whatever noise sits in the gaps.","hero":{"kind":"plate","image":null,"alt":null,"caption":null},"blocks":[{"t":"h2","id":"compression-does-not-make-anything-louder","runs":[{"text":"Compression does not make anything louder"}]},{"t":"p","runs":[{"text":"A compressor turns down anything above a threshold. That is the entirety of what it does. It has no mechanism for making sound louder."}]},{"t":"p","runs":[{"text":"What makes it louder is the make-up gain you add afterwards. Once the peaks have been pulled down, there is headroom, so you can raise the whole signal, and the quiet parts come up with it. Hence the only description of compression worth memorising: "},{"text":"turning the loud bits down so the quiet bits can come up.","b":true}]},{"t":"p","runs":[{"text":"Understanding that changes how you set it, and it explains the failure mode at the end of this lesson."}]},{"t":"h2","id":"do-it-in-this-order","runs":[{"text":"Do it in this order"}]},{"t":"p","runs":[{"text":"Clean the performance, then fix the tone, then control the dynamics, then set the loudness. In that order."}]},{"t":"p","runs":[{"text":"Out of order, the compressor reacts to noise you are about to remove, and your EQ shapes a signal you are about to change. 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A very fast attack dulls speech and is a common cause of a voice that sounds oddly soft."}],[{"text":"Release 100 to 200 ms, or auto."}],[{"text":"Make-up gain until the compressed version matches the uncompressed version in perceived level, so you are judging the sound and not just the volume."}]]},{"t":"p","runs":[{"text":"The failure mode.","b":true},{"text":" If the background hiss rises and falls between sentences, you are over-compressing. During speech the compressor is pulling the level down; in the gap there is nothing above the threshold, so nothing is being pulled down, and the full make-up gain lands on the room noise. That swelling and receding is the sound of too much gain reduction. Back it off, or gate gently, or fix the noise floor at the source."}]},{"t":"h2","id":"de-noising","runs":[{"text":"De-noising"}]},{"t":"p","runs":[{"text":"It works by learning a profile of a steady sound and subtracting it in the frequency domain. So it handles hum, fans and hiss well, and anything that varies badly."}]},{"t":"p","runs":[{"text":"Push it hard and you get the characteristic artefacts: an underwater quality, and small warbling tones sometimes called birdies, which appear where the subtraction has removed most but not all of a frequency band. Six to ten decibels of reduction is usually inaudible. Twenty is usually obvious."}]},{"t":"p","runs":[{"text":"Take the least you can live with. A slightly hissy voice is far easier to listen to for ten minutes than a clean one that warbles."}]},{"t":"h2","id":"loudness-and-why-louder-is-pointless","runs":[{"text":"Loudness, and why louder is pointless"}]},{"t":"p","runs":[{"text":"Streaming platforms normalise. Push your file louder than roughly −14 LUFS and YouTube or Spotify will turn it back down, and all you have achieved is a squashed, airless dynamic range that arrives at the listener at the same volume as everyone else’s."}]},{"t":"p","runs":[{"text":"Aim for around −14 LUFS integrated for video platforms, around −16 LUFS for podcasts, with true peak no higher than −1 dBTP. Free ways to measure: Resolve’s Fairlight page has a loudness meter, ffmpeg’s "},{"text":"loudnorm","code":true},{"text":" filter measures and applies, and Youlean’s free loudness meter plugin works in most hosts."}]},{"t":"h2","id":"the-free-toolkit-and-ten-seconds-today","runs":[{"text":"The free toolkit, and ten seconds today"}]},{"t":"ul","items":[[{"text":"Audacity","b":true},{"text":": free and open source, does every step above, including a usable noise reduction."}],[{"text":"DaVinci Resolve, Fairlight page","b":true},{"text":": free, a proper mixer with compression, EQ, metering and a ducker."}],[{"text":"Reaper","b":true},{"text":": an evaluation that never expires and a personal licence around $60, as of 2025."}],[{"text":"Ocenaudio","b":true},{"text":", "},{"text":"Ardour","b":true},{"text":", "},{"text":"Cakewalk","b":true},{"text":" on Windows: all free or near enough. On a phone, "},{"text":"CapCut","b":true},{"text":"’s audio enhancement is fine for speech."}]]},{"t":"h3","id":"ten-seconds-today","runs":[{"text":"Ten seconds today"}]},{"t":"p","runs":[{"text":"Take one minute of your voice, apply a high-pass filter at 100 Hz, and A/B it. That one control is usually the largest single improvement available to you."}]}],"check":{"question":[{"text":"After compressing a voiceover fairly hard, an editor notices the background hiss swelling up between sentences and receding when the person speaks. 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There is too much gain reduction."}],"correct":true,"tempting":null}],"order":[1,3,2,0],"why":null},"prev":{"slug":"eq-in-three-moves","title":"Three EQ moves that cover most voices","minutes":10},"next":{"slug":"de-essing-and-plosives","title":"Wind, hiss, and why both are placement problems","minutes":10}}}