windows notify.wav

Waveform audio file Reference

A .wav file contains audio in the Waveform Audio File Format. The container uses the RIFF structure, and the audio is in most cases uncompressed PCM. The quality is high, but the files are large. Microsoft and IBM introduced the format, and all common audio tools can read it. System sounds and audio recordings frequently use .wav files.

A file extension is only a part of the file name. It does not give a guarantee about the format or the content of a file. But on Windows, the extension selects the program that opens the file.