Why does the pitch and rhythm of my speech change what I mean?

The word prosody refers to the tune and rhythm of language.

In spoken language, prosody provides information beyond the dictionary definitions of the words we say. Consider how you’d say the word “okay,” in the following scenarios:

• A coworker says, “I’ll call you at two o’clock.”
• Someone tells you that you won a free vacation.
• Your teenage child calls in the middle of the night and says, “I have to tell you something.”

The same word can sound different, depending on the message we want to express. Prosody describes changes in pitch, tone, speed, emphasis, and volume that are meaningful to the listener. Different languages, dialects, accents, and idiolects use prosody differently. In English, prosody can be used to indicate a question. Using higher tones at the end of your sentence is an easy way to signal to the person you’re talking to that you’re asking them something—and expecting an answer.

Prosody can also convey emotion, sarcasm, and importance.

When talking to infants, people typically exaggerate elements of natural prosody. Speech directed at babies may have longer pauses between sentences or may sound more musical, with a wider range of pitches. Scientists have shown that the patterns of tone, stress, and speed are recognized by infants as young as six months, and that these patterns are useful to infants while they learn language, helping them to identify where words or phrases begin and end. Toddlers even “practice” prosody through their babbling, using tones and patterns of syllable length that match adult speech in their native language.