Couldn't find it on the Play store by searching for the name and the developer's name: if it is not just me then your app is very hard to discover.
So I am installing it through the link you provided, which directed me to a "install success" page saying "your purchase is successful" even if your app is free. Another obstacle to adoption :-)
Last, I was not informed on the page of the app' size. Seeing what it does and the time it takes to download I am afraid it could be huge? Third obstacle :-)
For me, searching for "whistle" on play store, I get the app as the third result (ignoring sponsored crap). Searching for "blazingbanana" gets me the app as the first result".
App info shows 218MB size, which I suppose is about what I'd expect for a model+app code :shrug:
Thank you for the feedback, I really do appreciate you taking the time to check it out and write out the comment! I'll look at adding a note about total app size in the description, it won't hurt.
As for discoverability / the "your purchase is successful" message, I'm not sure what else I can do, I've set it to free, no ads etc in Google Play. Maybe I need to hit a few more keywords for transcription so it surfaces it more.