Prosody

The patterns of stress, rhythm, intonation, and timing in speech that convey meaning beyond the literal words. Prosody communicates emotions, emphasis, questions versus statements, sarcasm, and conversational cues like turn-taking signals. For AAC users relying on text-to-speech output, prosodic features are often limited or absent, making it harder to convey tone, emotion, and conversational intent. The flat quality of synthetic speech can make backchanneling utterances sound unnatural—SLPs noted that default synthetic versions of backchanneling phrases are "pretty bad... not very natural."