This function reads aloud the selected text in English using the MacOS system's 'say' command.
It uses the voice specified by the parameter `systemVoice`. The default voice is "Alex". It only works on MacOS systems.
Usage
speakInEN(systemVoice = "Alex")
Value
A message indicating the completion of the speech is returned.
Arguments
systemVoice
The voice to be used for speech. Default is "Alex".