What instrument can be heard but not seen?

Why this works

This riddle plays with the idea of an "instrument" being something that produces sound. While we often think of traditional instruments like guitars or pianos, your voice is also a powerful instrument that creates sound. The twist comes from the fact that while you can hear your voice, you can't physically see it; you can only see the person speaking or singing. This clever use of language challenges our usual perceptions of what an instrument is and how it can be experienced!