Why a backwards sound is so strange
Play a piano note and you hear a sharp knock followed by a long, fading ring. Flip it and the ring comes first, swelling from nothing, and then the sound ends in a sudden stop where the knock used to be. The notes are all still there. What changed is the shape of loudness over time, known as the envelope.
Nearly every natural sound has an attack that is quick and a decay that is slow. Plucked strings, struck drums, spoken consonants and slammed doors all behave this way. Reversal swaps them, so the slow part leads and the quick part trails. The ear is not used to sounds that grow gently and then get cut off, and that unfamiliarity is why reversed audio feels eerie, magical or comic depending on the source.
This tool reverses the entire file in one go. It plays the samples in the opposite order, start to end, with no time-stretch, no pitch change and no filtering. The result has the same length and the same tone color as the source, only running backwards.
How to use it
Open a file, wait for the waveform, and the reversed version is ready. There are no knobs on this page because there is nothing to choose: a file is either played forwards or backwards. The space bar plays and pauses.
The Result and Original buttons keep the same moment of the track, so you can flip back and forth while the audio plays and hear how the two directions differ. A quick comparison on a short, punchy part gives a good feel for what the end of the recording sounds like when it becomes an introduction.
When you are happy, pick one of the MP3 bitrates, or a WAV depth of 16 or 24 bits. A size estimate is displayed ahead of the download, and the tool name is added to the file name. For a long file on a slow device, give it some seconds to process; files up to 250 MB are accepted.
What reversing does to common sources
The table in the Numbers tab sums it up for four kinds of sound. A struck note rises out of silence and stops dead. A cymbal crash turns into the classic riser that producers use to lead into a drop. Speech becomes a stream of swelling vowels that hit hard consonants, and it is not intelligible, though the rhythm and mood of the voice survive.
A few experiments make the effect clear. Reverse a snare drum and you get a short suck-in before the beat. Reverse a guitar strum and the chord appears to inflate. Reverse a door closing and it seems to open on its own. Short sounds with a strong attack give the biggest change; sustained pads, drones and wind change very little, since they have no sharp front to flip.
Whole songs reversed are mostly a curiosity, although a few seconds of one in a transition can be striking. Try reversing the last bar of a track and placing it before the next one, so the music seems to be pulled into the next section.
Another trick uses the order of the steps rather than the sound itself. Reverse a clip, trim a piece out of it with the audio trimmer, and reverse that piece again. You end up with a forwards excerpt that began life as the quiet end of the original, which is a quick way to make unusual short samples out of a longer recording.
The reverse reverb recipe
This trick is a producer favorite: a vocal or a snare that is preceded by a ghostly swell of its own echo. You can make it with three tools in about a minute.
First, reverse the clip on this page. Now the sound plays backwards and its attack sits at the end. Second, use the Continue with the result in link under the tool to open the reverb page with the reversed audio already loaded. Add generous reverb, for example the Hall or Cathedral preset, with a decay time of two to four seconds. Because the sound is reversed, the reverb tail that normally follows a sound now follows the backwards version.
Third, save that result, open it here again and reverse it once more. Everything flips once more. The original sound is forwards again, and the tail that trailed the backwards version now runs in front of it: a swell that builds up and leads into the word or hit.
Give the effect room. A tail needs quiet space to ring out, so start with a clip that has a second or two of silence at its beginning, which becomes the end after the first reverse. For a short vocal word, a decay of about two seconds is a good start; for a snare, try the Small room or Hall preset. If the swell is too loud against the sound, lower the Reverb knob on the reverb page and run the recipe again. The home page studio can also run the whole recipe as one chain: pick Reverse reverb and press play.
Ideas for creative use
Riser and sweep effects come from reversing crashes and cymbals. Record a lid dropped on a pot, reverse it and you have a short whoosh for a video transition. Reversed reverb tails on a piano chord give a dream-like entrance.
A voice note reversed can be used for a puzzle or a secret message in a game: a friend has to reverse it again to read it. Some musicians reverse a guitar part for a psychedelic effect, then learn to play along. Foley artists reverse sounds to make something recognizable but strange.
Reversal also turns up in sound design for horror and sci-fi: a reversed breath, a reversed scream, a reversed engine. The cost of experimenting is nothing. Load a sound, listen to it backwards and decide.
A last idea for video makers: reverse the sound of something being assembled, such as a cup being filled or a page being torn, to get a clip that appears to rewind. Pair the reversed audio with reversed footage and the two stay in sync, because both run through the same moments in the same opposite order.
If a reversed result sounds too harsh when it ends, remember that the abrupt stop is the original attack. Add a short fade out with the fade tool to soften the final moment, or keep it blunt when you want a stinger. The choice is entirely musical, and listening to both takes ten seconds.
Reversing on a phone
The page works in the browser of an iPhone or an Android phone, so no app is needed. Open the page, choose a file from the phone, then follow the same three steps. Save the result, and it lands where your browser puts downloads. A phone also holds videos, and the page can take the sound of most MP4, MOV and WebM files; the reversed result is an audio file.
A phone with limited memory may find a very long file slow. If the audio is more than a few minutes long, trim the part you need first with the audio trimmer, and reverse only that. It is quicker, and a short reversed clip is usually what you want anyway.
Reversing in a digital audio workstation such as Logic Pro is also possible; many editors include a reverse command for a selected region; the exact menu differs between programs and versions. That is the right place if you are already deep in a project. This page is the quicker route when you only have a file and a browser.
Quality, formats and rights
Reversal is lossless as a processing step, since the same samples are simply read in the opposite order. Any loss comes only from saving as MP3. If you intend to keep editing, choose WAV so the audio is not re-compressed between steps, and make the final MP3 at the end.
One practical point: some MP3 files have a small silent gap at the start from the encoder. After reversing, that gap can end up at the end of the clip. It is short and rarely noticeable, but if you want a perfectly tight result, trim the end afterwards.
Reverse files that are yours, or that you are permitted to use. Nothing is fetched from streaming sites or web addresses, and nothing of yours is uploaded.
Stereo files stay stereo, and the left and right channels are reversed together, so the sense of position survives. A sound that moved from left to right in the original now moves from right to left, which is another small giveaway that the clip is running backwards.
Privacy in a sentence or two
The reversed audio is produced by your own browser, from a file that never leaves the device. Your latest file is remembered in this browser, which lets a following tool offer it, and wiping the site data erases that memory.
Frequently asked questions
How do I reverse audio?
Drop a file on this page and it is reversed right away; there is nothing to configure. Listen with the space bar, compare Result with Original, then download the backwards audio as MP3 or WAV. The file stays on your device the whole time, and long clips just take a little longer.
What is reverse audio?
Reverse audio is a recording played from its last sample to its first. Because most sounds begin with a sharp attack and end with a slow fade, the reversed version swells up and stops abruptly. It is used for risers, transitions, ghostly effects and creative sound design.
How do I reverse audio on iPhone?
Open this page in the browser on your iPhone, choose a file from the phone, and the audio is reversed inside the browser. Then download it as MP3 or WAV. No app has to be installed, and the file is not uploaded to any server.
How do I reverse audio on a phone?
The steps are the same on Android and iPhone: open the page, pick the audio file, listen to the reversed result, and save it. For long recordings, cut the part you need with the audio trimmer first, which is faster on a small device and gives a shorter file.
How do I reverse audio in Logic?
Logic Pro has a reverse function for a selected audio region, found in the audio editor's functions (menu names differ between versions), so you can do it inside a project. If you only have a file and no project open, reversing it here and importing the result is simpler and quicker.
Can I make a reverse reverb effect?
Yes. Reverse the clip, continue with the result in the reverb tool and add a long decay, then bring that result back and reverse it again. The reverb tail now builds up before the original sound instead of following it, as the recipe above describes.