Here some practical advice how to really hear the sounds - I fear that it is not so obvious in this case, especially when there is no instructions in the book. Their "USB" is just a memory stick which connects to a normal size USB port of a computer - after you have figured out how to get it out of its holder (it took some time for me). It does not need much power but just the right angle, and it is relatively easy to put back to the holder. The stick contains 11,8 GB of data, so you don't necessarily want to copy it all to your phone. I copied just the folder containing the files associated with the book (277 MB) so that I can listen them while reading the book. I copied them using a cable to the birdsounds folder of my Android phone and listen them using Samsung music app. (With iPhone you need to do this different way). "The key species booklet" is there in two parts and two file formats: two pdfs and two epub - type ebooks. I copied the latter to a cloud drive (260 MB), in this case to Onedrive, then downloaded them to my iPad using the Onedrive app and then send those from Onedrive app to Books app. It is a very nice ebook, with photos and sounds well integrated.
