The distance within which someone can hear you; range of hearing.
From 'ear' (the organ of hearing) combined with 'shot,' originally meaning the distance an arrow could travel, metaphorically applied to the distance sound could carry.
The term 'earshot' is a perfect example of how English borrows metaphors—medieval people used 'shot' for any distance one could project something (arrow, voice, cannonball), which is why we say 'out of earshot.'
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