Review of audio transmitter circuit

I’ve designed this piezo buzzer circuit to transmit data using frequency shift keying. But I’m not an expert. Can someone take a look and let me know if it looks alright?

Looks good to me.

Current circuit is fine due to impedance matching. However, adding a flyback diode would help protect the circuit from damage. Schottky diodes are recommended for their fast switching ability. Here’s one that would work.