Use the free Audio Echo Delay Adder below: your data never leaves your browser — all work happens on your device, and nothing is uploaded to any server.
Echo versus reverb
People often confuse echo and reverb, but they are different effects with different sounds. Reverb is a dense wash of thousands of reflections that blur together. Echo is a small number of distinct repeats that you can count: the sound comes back, then comes back again, quieter each time, like shouting into a canyon. A delay unit creates echo. A reverb unit creates a space. Both have their place, and this tool is for the first one.
Echo suits rhythmic material. A guitar riff with a dotted-eighth echo answers itself between the beats. A vocal with a short slapback echo sounds thicker and more present. A dub track with long feedback echo turns a single note into a cascading pattern. Speech with heavy echo, on the other hand, quickly becomes hard to follow, so echo is mostly a music and sound-design effect rather than a podcast tool.
How the echo is built
The tool builds a classic delay network in your browser. Your audio passes through a delay line set to the time you choose, in milliseconds. Part of the delayed signal is fed back into the delay line, which creates the repeats: each pass through the loop is quieter by the feedback amount. A separate mix control decides how loud the echoes sit against the dry original. The feedback control is capped at 0.8 on purpose, because higher feedback can build into a loud runaway loop that never decays.
You set three values: delay time, feedback, and echo mix. Delay time decides the spacing of repeats. At 400 milliseconds, repeats land a little less than half a second apart. Feedback decides how many repeats you hear: 0.2 gives one or two audible repeats, 0.4 gives a clear tail of several, and 0.7 gives a long, dreamy cascade. Mix decides prominence: 0.2 keeps echoes subtle, 0.5 makes them a feature of the sound.
How to use it
Upload your file, set the three controls, and press Process. The tool renders the result offline with two extra seconds of tail, so the final repeats are allowed to fade instead of being chopped off. Listen with Play processed before downloading. If the echoes fight the rhythm, adjust the delay time: try the companion delay time calculator to find a time that matches your song tempo, such as a quarter note or a dotted eighth at your BPM. Echo in time sounds musical; echo out of time sounds like a mistake.
For a first experiment, try a delay of 350 to 450 milliseconds, feedback of 0.35, and mix of 0.35 on a guitar or vocal line. That is a versatile starting point that adds depth without taking over. For slapback, the classic rockabilly sound, use a short delay of 100 to 150 milliseconds, low feedback around 0.1, and a modest mix. For dub-style cascades, use 500 milliseconds or more with feedback near 0.6 and listen carefully to the tail.
Where echo shines, and where it does not
Echo shines on sparse material: a single guitar line, a vocal phrase with space around it, a drum hit in an otherwise empty bar. It struggles on dense, fast material, where repeats pile onto new notes and turn the mix into soup. It also struggles on speech that must be understood word for word, because each repeat competes with the next word. The rule is simple: echo needs space to breathe, so give it material with space in it.
Like every tool in this batch, the echo adder works entirely in your browser and downloads a real WAV file. No account, no upload, no waiting. Add the repeats, check the tail, and keep the original safe for the next idea.