• 音おと — sound
• 音楽おんがく — music
• 発音はつおん — pronunciation
• 足音あしおと — footsteps
• 物音ものおと — a noise; sound of something
• 音声おんせい — voice; audio

“音” is used for everyday sounds, music, and speech-related terms. You’ll see it in words like 音楽 (music), 発音 (pronunciation), and 物音 (a noise), so it’s very practical early on.