How to make slowed + reverb songs (free, in your browser)
What makes a song sound “slowed + reverb”
Slowed + reverb is two simple moves. First you play the song slower, usually somewhere between 75% and 90% of its original speed. Then you wash it in reverb so every note leaves a long, dreamy tail. That’s the sound behind late-night TikTok edits and hour-long YouTube loops.
The detail most guides skip: in the classic version, the pitch drops along with the speed, just like slowing down a record. That lower, heavier tone is half the vibe. If you slow a song down but keep the original pitch, it sounds stretched rather than slowed. So in the steps below, you’ll turn pitch preservation off on purpose.
You don’t need Audacity, GarageBand or any download. Both steps run right in your browser with free tools, and your audio stays on your device.
What you need
An audio file of the song: MP3, WAV, M4A or any other format your browser can play. If a file won’t open, convert it to WAV or MP3 with the audio converter first.
Two free tools: the Audio Speed Changer for the slow-down and the Reverb Generator for the tail. Headphones help a lot when you judge the reverb.
Step 1: Slow the song down (and let the pitch drop)
Open the Audio Speed Changer and drop your song onto the upload area.
Untick “Try to keep the original pitch”. It’s on by default, and leaving it on gives you the stretched sound instead of the classic slowed one.
Drag the speed slider to 0.80x. That’s the most common slowed + reverb setting and a safe place to start. Click “Change speed to 0.80x”, listen to the preview, and adjust in 0.05 steps until it feels right. Then click “Download WAV”.
Keep the file as WAV for now. Converting to MP3 between steps throws away detail you’ll want when the reverb goes on.
How much the pitch drops at each speed
When pitch follows speed, every slowdown lowers the song by a fixed number of semitones (a semitone is one piano key). At 0.90x the song drops by about 1.8 semitones, which is subtle and keeps vocals natural. At 0.85x it drops about 2.8 semitones, noticeably moodier. At 0.80x it drops about 3.9 semitones: the classic slowed sound, with deeper vocals. At 0.75x it drops about 5 semitones and voices start to sound like a different singer.
Length changes too. A 3-minute song becomes 3:20 at 0.90x, 3:45 at 0.80x and 4:00 at 0.75x.
Rule of thumb: fast, bright pop songs can go down to 0.75x. Songs that are already slow or have a very deep male vocal usually sound best at 0.85x to 0.90x, before the voice turns muddy.
Step 2: Add the reverb
Open the Reverb Generator and upload the slowed WAV you just downloaded.
Pick a starting sound. Hall (2.5 seconds of decay, 40% mix) is the best all-round choice for slowed + reverb. Cathedral (5 seconds, 50%) gives the huge, floaty version you hear on hour-long loops. Plate is brighter and works well on vocal-heavy songs.
Fine-tune with the two sliders. Decay time is how long each note rings out, and 2.5 to 4 seconds is the sweet spot for this style. Wet/dry mix is how much reverb you hear compared with the dry song. Start around 30% to 40%. Above 60% the song starts to sound like it’s playing in the next room.
Click Apply, listen through headphones, and download the reverb WAV when you’re happy.
Settings by mood
Late-night chill: 0.85x, pitch drops, Hall reverb, 3 seconds of decay, 35% mix. Slower and warmer, but the lyrics stay clear.
Classic TikTok slowed: 0.80x, pitch drops, Hall reverb, 3.5 seconds of decay, 40% mix. The sound most people mean by “slowed + reverb”.
Underwater or dreamcore: 0.75x, pitch drops, Cathedral reverb, 5 to 6 seconds of decay, 50% mix. Heavy and hazy, made for loops rather than singing along.
Just a little slower: 0.90x with pitch preservation turned on, Room reverb at 20% mix. Good when you want to learn a song or play along at an easier tempo.
Why you slow first and add reverb second
Order matters. If you add reverb first and then slow the song, the reverb tail gets slowed and pitched down too. It turns into a long, low rumble that eats the bass and blurs the vocals.
Slowing first and adding reverb last keeps the tail crisp, and you control its length exactly with the decay slider.
Make a sped-up (nightcore) version instead
The same two tools make the opposite effect. In the Audio Speed Changer, untick pitch preservation and set the speed to 1.20x to 1.30x. That raises the pitch by about 3 to 4.5 semitones, giving the bright, high-energy sped-up sound.
Sped-up versions usually need little or no reverb. Try the Studio or Room sound at 10% to 15% mix just to add some space. If you only want a different key without changing the tempo, use the Pitch Changer instead.
Troubleshooting
It sounds muddy or boomy: lower the reverb mix first, then shorten the decay. If the song itself is bass-heavy, pull the 62 Hz and 125 Hz bands down a few decibels in the audio equalizer before adding reverb. Speeding the slowdown back up to 0.85x also helps.
The vocals sound robotic or warbly: you probably left “Try to keep the original pitch” turned on with a big speed change. Time-stretching is impressive, but at 0.75x and below it can smear vocals. Turn it off for the classic sound.
It’s too quiet compared with the original: reverb spreads energy across time, so the result can feel softer. Lower the mix slightly rather than pushing everything louder, which can clip.
The tool says the file needs more memory: very long files or extended mixes can exceed what your browser can handle. Trim the part you need with the audio trimmer first, or try a shorter file.
Sharing your slowed + reverb version
Making an edit for yourself is the easy part. Uploading it publicly is different: a slowed + reverb version of someone else’s song is still their song, so platforms can mute it, block it, or send revenue to the rights holder. Post edits of tracks you have permission to use, and use platform sound libraries where they exist.
Frequently asked questions
What speed is best for slowed + reverb?
0.80x (80% speed) with the pitch allowed to drop is the most common starting point. Use 0.85x to 0.90x for songs that are already slow or have deep vocals, and 0.75x for an extra-heavy, dreamy version.
Should the pitch drop when I slow a song down?
For the classic slowed + reverb sound, yes. Letting the pitch fall with the speed gives the deeper, record-slowed tone. Keeping the original pitch makes the song sound stretched instead of slowed.