An audio jack is very common. Some even come with speakers. They are usually not very good but they get the job done in a pinch. I use 2 computers connected to

An audio jack is very common. Some even come with speakers. They are usually not very good but they get the job done in a pinch. I use 2 computers connected to the same monitor via hdmi and use barrier (and a script) to switch screens. The audio for the correct monitor gets activated automatically. It's very convenient.