Question

does the escaping air make the high-pitched whine on a dental drill?

Answer 1

Short answer: partly — but not just the escaping air. The characteristic high-pitched “whine” of a dental handpiece mainly comes from aerodynamic noise generated by an air turbine spinning extremely fast inside the head and the resonances that follows. The exhaust/coolant air contributes hissing and can accentuate the pitch because air leaving through ports and cavities resonates, but the dominant sound source is the turbine/airflow interaction (and sometimes vibration of small parts).

Notes:
- Air-driven (turbine) handpieces are much noisier than electric micromotor handpieces for this reason.
- Water spray and bur-tooth contact can add additional noises.
- Modern electric or well-maintained handpieces run noticeably quieter.