Bidirectional Audio Redirection
Use your local microphone in the remote RDP session through the browser.
By default, the microphone redirection will enabled.
To enable sound redirection, you would need to open the Thinfinity® Remote Desktop Manager, go to the Access Profile of your connection, then go to the Resources tab and finally check the Enable Sound option:
When you have the microphone redirection enabled, you would need to allow access to said microphone on your browser as well:
You can copy the file 'web.settings.js' to "C:\ProgramData\Cybele Software\Thinfinity\Remote Desktop Server\DB". This way, your settings won't be lost when upgrading Thinfinity Remote Desktop in the future.