Young children acquire knowledge of these prosodic features as well as the spe· cific sounds used in a language through interactions wilh people in their environ-ment. Children's auditory perception of these prosodic features contributes to both !heir phonological knowledge and their subsequent somantic knowledge. Infants' perception of the speech intonation of those around them is evident when they begin lo babble aud appear lo mimic the intonation of others. Infants learn to sense when U10ir parent or caregiver is happy, excited, calm, tense, or angry from the intonation, loudness, tempo, or rhythm of the adult's speech.