This script uses PulseAudio commands to create a unified audio stream for microphone and system sounds, for live streaming.

stream-audio

# create a virtual sink for both audio streams
SINK_ID=$(pactl load-module module-null-sink sink_name=StreamAudio sink_properties=device.description=StreamAudio)
 
# find microphone source ID
MIC_ID=$(pactl list short sources | grep "Snowball" | cut -f1)
 
# loop microphone to the new sink
MIC_LOOPBACK_ID=$(pactl load-module module-loopback sink=StreamAudio source=$MIC_ID)
 
# find stereo monitor ID
STEREO_ID=$(pactl list short sources | grep "analog-stereo.monitor" | cut -f1)
 
# loop system sounds to the new sink
STEREO_LOOPBACK_ID=$(pactl load-module module-loopback sink=StreamAudio source=$STEREO_ID)
 
cleanup() {
    pactl unload-module $MIC_LOOPBACK_ID
    pactl unload-module $STEREO_LOOPBACK_ID
    pactl unload-module $SINK_ID
    exit
}
 
# call cleanup when the program is interrupted
trap cleanup INT
 
while [ 1 ]; do
    # loop until interrupted
    sleep 1
done