I'm having difficulties replacing callout sounds on Big Buck Hunter and I'm hoping someone can advise me what settings to check. One thing that might be relevant is that the sounds are indicated to be "Undersampled 2X" in Pinball Browser. I am using Audacity, and am converting a sound file to one track (mono), changing the Project Rate (Hz) to 24000, and exporting the file as a .wav file with encoding set as "SIgned 16-bit PCM) and no track metadata. The sounds import fine into Pinball Browser, and I can play them fine within Pinball Browswer. HOwever, once installed in the actual game, the sounds are silent. Does anyone have any ideas or suggestions of things to check, etc.? TIA.

I figured out what the problem was. I was confused by the "Project Rate (Hz)" field vs. the Track Sample rate available from the top menus. The steps I followed instructed that I should change the "Project Rate (Hz)" in the bottom left of the main Audacity interface screen to 24000 (which I did). I included a screenshot of what that looks like in this post.
Project Rate (Hz) (resized).png

HOWEVER, what was missing was the Track Sample Rate, which remained at the level from the original source. You can see in the attached image "Track Sample Rate" that this value is 48000 Hz.
Track Sample Rate (resized).png

To fix the track so that it's sample rate is 24000, you need to go to the menu TRACKS > RESAMPLE... and change the value there to 24000.
Menu. Tracks - Resample (resized).png

I hope this helps others.