Many of the audio files used in these classes were originally recorded by my daughter during her childhood, some more than ten years ago. A few others are relatively recent.
Regarding the earlier recordings, I did not have access to audio editing software at that time. As a result, some minor deficiencies may be noticeable in a few of those audios.
In recent years, a few new audios created by voice cloning have also been added.
The Impromptu Speech audios are completely original recordings made many years ago. I have not yet had the time to review them for technical perfection.