I have generated a beamer pdf containing a link to an external player in order to play a sound. I am opening it with the macOS pdf viewer preview and when I hover the mouse pointer over the clickable text, the location of the .wav file is shown but when I click on the text nothing happens. Here is the minimal working example:
\documentclass{beamer}
\usepackage{multimedia}
\begin{document}
\sound[externalviewer]{test}{sound.wav}
\end{document}
Macs Preview.app is known to not play nicely with the multimedia package.
I suggest to use another pdf viewer instead. For example, your code works fine with