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About this tool
Work out how many decibels to duck an intro music bed under a voiceover, and what the mixed level lands at.
This calculator works out the level a music bed should be ducked to so it sits a chosen number of decibels below the voiceover, then power-sums the two to show where the combined mix lands. It uses the standard decibel relationships — amplitude ratio 10^(dB/20) for the fader move and 10·log10 power summing for the mix — so the answers match what a meter will read. Podcasters, video editors and radio producers use it to set an intro duck without guessing at the fader.
Open Intro Music Level Calculator on AltFTool — it loads instantly in your browser.
Enter the values you already know.
Fine-tune the options to match your scenario.
Read the result and use it in your planning or reporting.
Shows the amplitude multiplier and percentage, ready to type into a mixer.
Uses power summing, so two equal sources add 3 dB rather than 6.
Flags when the combined mix would break your true-peak ceiling.
Around 18 to 20 dB below the voice for spoken-word content, which keeps the bed audible but never competes. Promos and adverts often sit closer at 12 to 15 dB, and cinematic trailers can go as tight as 8 dB where clarity matters less than impact.
Apple Podcasts asks for about −16 LUFS integrated for stereo, Spotify and YouTube normalise near −14 LUFS, EBU R128 broadcast is −23 LUFS and US ATSC A/85 is −24 LKFS. Keep true peaks at or under −1 dBTP for streaming, or −2 dBTP for A/85 broadcast.
Because uncorrelated sources add in power, not amplitude. A bed 20 dB below the voice raises the combined level by only about 0.04 dB, while a bed at the same level as the voice adds a full 3 dB.
A duck-down of roughly 80 to 250 ms and a return of 400 to 900 ms is a safe starting range. Faster attacks catch the first syllable but can sound pumped; slower releases stop the bed bouncing between short words.
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