Audio is played through speakers or headphones using a standard 3.5mm jack by default. No separate audio accessory is needed if you are going to use an HDMI cable to connect to a monitor with speakers, since audio can be played directly through the display; but you should firstly install pulseaudio tool in Lemuntu and edit /etc/pulse/default.pa as following.
Step 1: Install pulseaudio
sudo apt-get install pulseaudio
Step 2: Select HDMI output
sudo apt-get install pulseaudio sudo nano /etc/pulse/default.pa ... ### use module-udev-detect -- see below -- for doing this automatically #load-module module-alsa-sink device=hw:0,0 # 3.5mm Jack output load-module module-alsa-sink device=hw:0,1 # HDMI output ...
Step 3: Restart system