The AV world starts with audio, literally – audio-visual. In this context, it usually refers to sound reinforcement for public address (PA systems) – amplifying a sound such as your voice to reach larger crowds. In ancient times, structures like the Greek amphitheaters naturally amplified sound.
Before the modern electronic age, passive acoustic megaphones, or bullhorns, were the primary sound amplifiers. The next breakthrough in audio technology came from Thomas Edison. He actually invented the precursor to the modern-day record player, which also utilized an acoustic horn to amplify recorded sounds. The first microphones and speakers were introduced to the world not long after that. The modern era of sound reinforcement is mature, having emerged over 100 years ago.
Simple PA systems use microphones and speakers for effective crowd amplification. Audio complexity increases with specially designed microphones, audio adapters, and large audio consoles that creatively mix vocals, instruments, and playback devices. Distribution systems connect these components to multiple speakers, enabling full-blown concerts in stadiums and arenas.