Merging multiple AIFF files from the command line Is there a way to put multiple commands in different voices into the same audio file. I know you can do this:

say -v "Cellos" "la di da" -o ex.aiff


But I have multiple commands in different voices such as:

say -v "Cellos" "la di da"
say -v "Bells" "di da da"


Is there a way to  have say put multiple phrases using different settings in to the same aiff or mp3 file? (If not, can I merge the individual files programmatically using terminal tools and commands?
Using sox:

sox 1.aif 2.aif output.aif


Using ffmpeg:

ffmpeg -f concat -i &lt;(printf %s\\n "file '$PWD/"{1,2}.aif\') -c copy output.aif