Add an echo effect to a voice or song: set the delay time, repeats, and tone, or bounce it left and right with ping-pong. Free, with no upload.
The echo effect adds repeats of a sound after the original. Delay time sets the gap between them, from 50 milliseconds to a full second. Repeats sets how much of each echo is fed back to make the next one, so 0% gives a single repeat and higher settings give a long trail. Echo tone dulls each repeat a little more than the last, as happens in a real space. Start from Slapback, Classic echo, or Canyon, or switch on ping-pong to bounce the repeats between the left and right speakers.
Short delays under about 120 ms thicken a vocal without sounding like a separate echo; longer ones are heard as distinct repeats. For music, a delay that matches the beat sits best — at 120 BPM a quarter note is 500 ms — and the BPM finder will tell you the tempo. The export is extended so the last repeats can die away. If you want a smooth wash rather than separate repeats, use audio reverb instead (the difference, and how to use both, is in reverb vs echo). Your audio never leaves your device.
Echo is one or more distinct repeats of a sound that you can hear separately. Reverb is thousands of reflections so close together that they blur into a continuous tail. Use echo for a rhythmic or dramatic repeat, and reverb to place a sound in a room.
Divide 60,000 by the BPM to get the length of one beat in milliseconds. At 120 BPM a beat is 500 ms, so 500 ms gives quarter-note repeats and 250 ms gives eighth notes. If you do not know the tempo, the BPM finder will measure it from the file.
It sends the repeats to alternate sides: the first to the left speaker, the next to the right, and so on. The original sound stays where it was. It is most noticeable in headphones, and the export is always stereo when ping-pong is on, even if the file you started with was mono.
Slapback is essentially one quick repeat at 110 ms, the sound associated with 1950s rockabilly vocals. Classic echo repeats every 350 ms at 40% and fades over several repeats. Canyon uses 650 ms at 60% with a darker tone for long, distant trails. Ping-pong bounces 300 ms repeats between left and right. Each preset sets every control, which you can then adjust: delay from 50 to 1,000 ms, repeats up to 85%, and echo tone from 1 to 16 kHz.
Long enough for the repeats to fall about 60 dB below the original, which is effectively silent, so it depends on the delay time and the Repeats setting. Classic echo adds roughly 3 seconds and Canyon about 9; with 0% repeats it's just the delay time plus a tenth of a second. The extension is capped at 15 seconds, and the size estimates beside the export formats already include it. Repeats stops at 85%, so the echoes always die away.