This is the english language pack for OpenRepeater that is required by the core SVXLink server. These are the sounds that get played over the air as spoken voice prompts. It is a customization based largely on the sounds provided in the Heather voice for SVXLink with some other voice prompts added in specifically for OpenRepeater and some custom modules.
Unlike the SVXLink sounds, these files are already processed into the correct format required to be played by the SVXLink core, so you don't need to run them through a script first. They simply need to be installed in to the file system at: /usr/share/svxlink/sounds/en_US
These sound files would typically already be built into a distributed IMG file of OpenRepeater. This repo exists to aid in the build process and to make the sound available to those creating custom builds, for example on an unsupported single board computer.