Of course, you and Wayne are right.
To NFBrown -
Turn the radio on.
Long press the menu button. This starts you with the TOOLS page.
Press the PAGE button once, to take you to the SD CARD page.
Below the title should be listed these folders:
[EEPROM]
[FIRMWARE]
[IMAGES]
[LOGS]
[MODELS]
[SCREENSHOTS]
[SCRIPTS]
[SOUNDS]
[UTILITIES]
and
opentx.sdcardversion (without brackets)
If those aren't there, then the Downloaded files have not been copied to the card in the correct place. You should delete everything on the card, and recopy from the download, so that the folders (and one file) are all listed at the top level, and not inside any other folder.
If they are listed as above, use the "-" key to move to the [SOUNDS] folder, and when highlighted, press "Enter"
Inside that are folders for various languages. For English, go to the [en] folder and select that. (the other languages are similar)
Inside there is one folder called [SYSTEM] and all your wav files.
If no .wav files, then they either did not get copied over, or are somewhere else in a wrong location.