International Morse alphabet
4 in Morse code
Hear the rhythm as short, short, short, short, long.
....-dit dit dit dit dah
30 second sound drill
Listen to the complete rhythm. Do not count its parts.
Ready
Hear 4 as one sound
At 20 WPM, the elements join into a recognizable audio shape. Farnsworth spacing leaves time after the complete character without changing that shape.