[mqyycvcj] Morse code triads

Listening to Morse code has the challenge that if you miss a beat, there is no chance to hear it again.  In contrast, if you blink while reading scrolling text, your eyes can backtrack to the reread the text you missed.

Design an audio signal that has some redundancy in time.  Simplest might be something like Morse code played at a certain frequency, the same message delayed by a small amount and played at a different frequency, then another delay and a third frequency.  A listener will hear and need to learn to interpret a sequence of chords, which is not too different from listening to music.