Send Audio to a Apple Tv/Airplay device via the /usr/bin/say command
/usr/bin/say -r160 -a "AirPlay" "hello world"
-r160 is Speech rate to be used, in words per minute
-a followed by device name or number.
Then your text.
To list your available audio device
47 Built-in Output
209 Soundflower (2ch)
74 Soundflower (64ch)
Using the numbers will work just as well in place of the device name.
/usr/bin/say -r160 -a 39 "Hover over a Method";say -r160 -a "Built-in Output" "I am back"
You can also use the -f option to use a text file as your speech text.
/usr/bin/say -f ~/Music/foo.txt -r160 -a 39
As you will notice say can expand tilde file paths
With say you can do a lot more like save speech text directly to audio file.
/usr/bin/say -o ~/Music/hi.aac Hello, World.
-o oupt file path. i.e ~/Music/hi
.aac file format
This saves a .acc file named hi.aac to the Music Directory.
Directory paths MUST exist before the command is run. The file does not need to exist first in the directory and if it does it will most likely be overwritten.
There are other formats you can use.
The man page say will show you the full list of the options.