By comparing infant-directed speech to spouse- and dog-directed talk, we aimed to investigate how pitch and utterance length are modulated by speakers considering the speech context and the partner’s expected needs and capabilities. We found that mean pitch was modulated in line with the partner’s attentional needs, while pitch range and utterance length were modulated according to the partner’s expected linguistic competence. In a situation with a nursery rhyme, speakers used the highest pitch and widest pitch range with all partners suggesting that infant-directed context greatly influences these acoustic features. Recent findings showed that these speakers expressed more intense positive emotions towards their infants and spouses than towards their dogs. Our results revealed different patterns, leading us to conclude that these acoustic features are not simple by-products of emotional speech. Instead, they are dynamically and functionally used in accordance with the speech context and the audience’s expected needs and capabilities.
