Listen — the imperative, one syllable, the whole instruction. Irish, éist. Not "hear," which happens to you, but "listen," which you do. Live monitoring: hearing yourself in the moment you are making the sound.
Irish éist, the imperative of éisteacht (listening); the plain, one-syllable command to attend rather than merely to hear.
Listen, given as a single-syllable instruction rather than a description of what happens to the ears. Live monitoring is this: hearing oneself in the very moment the sound is being made.