From DLE Legal The stenotype machine (also called the stenograph) that is used by court reporters and transcriptionists has a special keyboard with only 22 keys.
The modern stenograph has two rows of keys on each side, which represent consonants, and four keys at the center, in front, with the vowels A, O, E and U. A bar across the top of the machine is used to type numbers.
The transcript that the machine creates may not be comprehensible to a layman, but for someone trained in shorthand writing it makes sense. The keys on the left are used to type the first letter of a syllable of the word, the keys on the right give the last letter of the syllable. The vowel keys are used for the vowels.
A stenographer usually presses three keys at once, which is known as a chord, to get a syllable. So a seven- or eight-letter word with three syllables, for instance, will take the stenographer only three strokes to type, while other people would need seven or eight strokes.
You may now be wondering how they type the missing alphabets. This is a valid doubt as the English alphabet has 26 letters but the stenograph has 22.
So, a stenographer spells out syllables in terms of phonetics. For example, the stenotype machine does not have the letter M in it. To type a syllable that starts or ends with M, the stenographer types P and H together to get the phonetics right. Similarly, for the letter N, the stenographer would use T, P, and H simultaneously. This may not make sense to a layman, but for a trained stenographer the final transcription will have all that they need.