How to make a Morse code audio file

27 October 2026 · 6 min read

A Morse code audio file is a recording of one steady tone, switched on and off in the pattern of dits, dahs and gaps. You can make one in three ways: record yourself sending it, build it piece by piece in an audio editor from exact timings, or have an app render a typed message for you. Whichever you choose, settle the speed and the pitch first, because they decide who can actually decode the file.

Pick the speed for the listener

Speed is hard to fix later without making the file again. Choose it for whoever will hear it, not for yourself.

Someone who has never heard Morse, such as a puzzle solver or the person you are giving it to. They will decode it with a chart, one letter at a time. Send each letter cleanly and leave long gaps between letters and words, so they can look each one up before the next begins.
A learner. Send the letters at a brisk character speed and stretch only the gaps between them (Farnsworth spacing). Each letter stays one recognizable sound instead of a string of beeps.
An operator. Standard spacing at an ordinary speed is fine.

All the timing comes from one number. At W words per minute a dit lasts 1200 divided by W milliseconds. A dah is three dits long; the silences are one dit inside a letter, three between letters and seven between words.

Speed	Dit	Dah	Gap between letters	Gap between words
5 WPM	240 ms	720 ms	720 ms	1680 ms
10 WPM	120 ms	360 ms	360 ms	840 ms
15 WPM	80 ms	240 ms	240 ms	560 ms
20 WPM	60 ms	180 ms	180 ms	420 ms

How long is a dit? Working out Morse timing from WPM has the arithmetic for any other speed.

Pitch matters less than speed, since the meaning sits in the lengths, not the note. There is no official Morse pitch. Pick a steady tone that is pleasant to hear for a minute or two, not a shrill one.

Record it live

The quickest file is a recording of you sending the message. Anything that makes a clean on and off sound will do: a practice oscillator with a key, a buzzer, or a steady hum or whistle. Record it with a voice recorder app on your Mac or your phone.

Record somewhere quiet, close to the microphone, so the gaps are silence and not room noise. Gaps full of hum are harder to hear as gaps.
Leave a second or two of silence before the first dit and after the last, so the start is not clipped.
Make two or three takes and keep the best. A live recording keeps your timing exactly as you sent it, uneven gaps included.

A live recording has character, and for a gift that can be the point. For a puzzle or for practice, where every gap has to be right, the next two methods are more reliable.

Build it by hand in an audio editor

If you want exact timing and have no key, an audio editor can do it. Many of them can generate a tone and a stretch of silence of a set length, which is all Morse needs.

Pick the speed and look up the dit length in the table above.
Generate a steady tone exactly one dit long, and another exactly one dah long.
Generate silences of one, three and seven units.
Lay the pieces end to end, letter by letter, copying tones rather than generating each one again.
Give each tone a very short fade in and out, a few milliseconds. A tone that starts or stops abruptly can click at each edge.
Leave silence at both ends, then export the file in a common format.

A worked example: HI at 10 WPM, where a unit is 120 ms. H is ...., four dits with three one-unit gaps between them, which is 7 units or 840 ms. Then a three-unit letter gap, 360 ms. Then I, .., two dits and one gap, 3 units or 360 ms. The whole word is 13 units, 1560 ms, plus the silence around it.

It is careful work, so keep hand-built files short: a name, a date, a word or two.

Render a typed message on a Mac

On a Mac, Dot & Dash takes the editing out of it. Set the speed (5 to 40 WPM), the Farnsworth spacing and the pitch (400 to 1000 Hz) first, in its Settings, on the General tab, because a typed message is made with them. Then type the message in Write, Send it to hear how it sounds, and share it as audio, from Write or later from the Library. You get an .m4a file of the message as the machine sounds it, made on your Mac and sent only where you send it. The file takes its name from the message’s first words, so rename it before you hide it in a puzzle. Audio sharing is part of the 24-hour trial and needs a license after it. It does not work the other way: Dot & Dash does not listen to audio, so it cannot decode a recording.

What to use a Morse audio file for

A puzzle. A short file hidden in an escape room or a treasure hunt, with a chart nearby. Keep it slow, with wide gaps, and check the file name: rename it if it gives the answer away. Morse code puzzles for escape rooms and treasure hunts has ideas that work for people who have never heard Morse.
A gift. A name, an anniversary date or a short line for someone close, sent so they can play it again whenever they like. A few words is plenty.
Practice. Make files of the letters and words you keep missing, then play them back and write down what you hear before you check the text. Make a batch and play them a day or two later, once you no longer remember which file says what.
An alert. A short Morse file can become a ringtone or an alert sound; Make a Morse code ringtone or alert sound covers length and timing for that.

Check it before you send it

Before the file goes anywhere, play it once without looking at the text and write down what you hear. If you cannot decode your own file, nobody else will. The usual faults are easy to spot this way:

Two letters heard as one. The gap between them is too short. AN, .- -., with its gap squeezed becomes P, .--..
One letter heard as two. There is a pause inside it. L, .-.., with a pause after the dah becomes A and I.
The first dit missing. There was no silence before the message, and the start got clipped.
A click on every tone. The edges need a short fade.

Remake the file rather than patching a gap here and there. A message with uneven spacing is harder to read than one that is evenly slow.

If someone sends you a file instead, copying it is a job for your ear: How to decode Morse code from an audio recording walks through it.

Questions

What format should a Morse audio file be?

Any common format your listener can play works, because Morse is a single tone and needs no special quality.

Can I make a Morse audio file without special software?

Yes. Record yourself humming, whistling or sending on a buzzer with a voice recorder, or build the file in an audio editor from tones and silences cut to the right lengths.

What speed should a Morse file for beginners be?

Send the letters at an ordinary speed and stretch the gaps between them, or slow everything down. Either way, give a beginner time to look up each letter before the next one starts.

How long should a Morse audio file be?

Short: a name, a word or a line. A long file is tiring to copy by ear, and a hand-built one takes longer to check and to fix.