To understand spoken words, listeners must appropriately interpret co-occurring talker characteristics and speech sound content. This ability was tested in 6- to 14-months-olds by measuring their looking to named food and body part images. In the "new talker" condition (n = 90), pictures were named by an unfamiliar voice; in the "mispronunciation" condition (n = 98), infants' mothers "mispronounced" the words (e.g., "nazz" for nose). Six- to 7-month-olds fixated target images above chance across conditions, understanding novel talkers, and mothers' phonologically deviant speech equally. Eleven- to 14-months-olds also understood new talkers, but performed poorly with mispronounced speech, indicating sensitivity to phonological deviation. Between these ages, performance was mixed. These findings highlight the changing roles of acoustic and phonetic variability in early word comprehension, as infants learn which variations alter meaning.