Audio systems let AI applications work with spoken language. They can turn speech into text, turn text into speech, identify who spoke when, support live voice agents, generate sound effects, dub media, and create music. The first API call is usually the easy part. The harder work is making the experience fast, clear, respectful of consent, and reliable enough to measure.

These capabilities show up in voice assistants, contact centers, meeting tools, accessibility products, media workflows, language learning apps, podcasts, and interactive tutors.

This chapter explains the main building blocks: speech-to-text, text-to-speech, batch versus streaming transcription, speaker diarization, and the latency tradeoffs behind real voice interfaces.