What is the correct format of audio files to be uploaded in my package?

Audio files should have .wav format, 16 bits, 8kHz, mono. Any other format could interrupt the broadcast, and the quality of the audio file can’t be guaranteed.

A easy to use and free tool to record audio messages is: https://www.audacityteam.org/

These are the settings to be used:

And these settings can be used to export the audio: