Free Audio Reverser for Songs, Voice and Sounds

What reversing does to a sound

Reversing a file plays its samples in the opposite order, so the last moment of the recording comes first and the first moment comes last. The pitch, length and loudness stay the same. What changes is the shape of each sound over time.

Most sounds start with a sharp attack and then fade away in a decay. Played backwards, the fade becomes a slow swell and the attack becomes a sudden stop. That swelling, inhaling quality is why reversed audio is easy to recognize even when you can’t tell what the source was.

Speech changes the most. Words are built from consonants and vowels in a fixed order, and reversal scrambles that order, so a sentence turns into syllables that sound close to a language you almost know.

Making a reverse reverb swell

The reverse reverb heard on vocals in film trailers, rock intros and dance music builds is a reverb tail that swells into a word or a note. It takes two reversals and one reverb.

1. Reverse the dry clip here and download the WAV.
2. Open it in an audio editor and add a long reverb with only the wet signal, so the file holds the reverb tail and none of the original. In Audacity, the Reverb effect has a Wet only box for this.
3. Drop the reverb file back into this page and reverse it again. The tail now builds up and ends where the original clip begins.
4. Place it on a track above the original so the peak of the swell lands on the first word or hit, and mix it in underneath.

Audacity 4 also has its own Reverse command under Effect ▸ Special, so the whole recipe can be done in one program. The guide to effects in Audacity shows where each effect lives, and the explainer on reverb covers how a reverb tail forms and decays. In a DAW, a reverb plugin such as Halo Reverb on a separate track does the same job.

Timing a reversed swell to the tempo

A swell sounds intentional when it lasts a whole number of beats. One beat lasts 60 divided by the tempo in BPM (beats per minute), in seconds. Find the tempo of the song with the BPM finder, then trim the swell to one of these lengths.

A reversed cymbal works the same way. Trim the crash so its reversed swell lasts one or two beats, and place it so it ends on the downbeat of the new section.

Playing the reverse singing challenge

In the reverse singing challenge, someone records a phrase, the recording is reversed, and a player tries to copy the backwards version. When the copy is reversed in turn, it should come out as the original phrase, usually garbled.

1. Record a short phrase with the voice recorder on your phone. Two to five seconds is plenty.
2. Reverse it here and play it a few times. Write the syllables down the way they sound.
3. Record yourself imitating the reversed version, sound by sound.
4. Reverse that recording. The closer the imitation, the more clearly you hear the original phrase.

Short words with clear vowels are the easiest. Consonants are the hard part: the hiss of an “s” becomes a fade-in, and a “t” lands on the other side of its vowel, so “cat” comes back as something near “tack”.

Phone voice recorders often save M4A files, which this page opens directly, so the recording needs no conversion first.

Backmasking and hidden messages in songs

Backmasking is a message recorded backwards on purpose into a track that plays forwards. Reversing the song is the only way to hear it as words.

John Lennon and producer George Martin both said the Beatles found the trick in 1966 during the sessions for Revolver. “Rain” was the first Beatles song to use it, with Lennon’s vocal reversed in the coda.

In the late 1970s and early 1980s, some religious groups claimed that backward messages could influence listeners without their knowing. In 1983 the Arkansas legislature passed a bill requiring warning labels on records with backmasking, and Governor Bill Clinton vetoed it. In 1990 a judge dismissed a lawsuit against Judas Priest over alleged hidden messages on the album Stained Class, for lack of evidence.

Research has found no effect on listeners. In 1985 psychologists John Vokey and J. Don Read played backward passages to test subjects, who could not tell what the messages were and did not change their behavior.

Most messages people find by reversing a song are phonetic reversals: sounds that happen to form words when played backwards. Listeners usually hear them only after someone tells them what to listen for. Reverse the song here and you can test any claim with your own ears.

Quality, length and format of the reversed file

The download is a WAV file at 16-bit, 44.1 kHz, the resolution of a CD. Reversing changes only the order of the samples, so the file keeps its length and loudness.

An MP3 or M4A is decoded before it is reversed and the result is saved uncompressed, so no second round of lossy compression is added. The cost is size: a stereo WAV at this resolution takes about 10.6 MB per minute, around eleven times as much as a 128 kbps MP3.

Reversing the download again restores the original order. Files recorded at 48 kHz, the usual rate for video, come back at 44.1 kHz, which audio and video editors open without trouble.

The whole file is reversed. To reverse one part of a song, cut it out first with the MP3 cutter, reverse the clip, then put it back in place in an editor. To reverse only the vocal or the drums, separate them with the stem splitter and reverse that stem.

Reversed audio in videos and edits

When a video editor has no way to reverse the sound of a clip on its own, export the audio track, reverse it here and import the WAV back onto the timeline. Line its start up with the clip and mute the original sound.

• A reversed crash or cymbal just before a cut, as a riser into the next scene.
• A reversed vocal line under a dream, flashback or horror sequence.
• A reversed word or sound effect as a quick transition in a short video.
• Reversed piano or guitar chords as an ambient bed: each chord swells in and stops, which keeps the bed moving.
• A riff played backwards as a starting point for a new melody. The notes stay the same and their order and rhythm change.

When the reversed file sounds wrong