Matlab does not have a generic USB interface, though it does utilise USB with the instrument control toolbox through the use of VISA or similar control protocol.
One very neat feature in Matlab is that you can generate signals with your PCs sound card, I am writing this on my cell phone so I can't post any link to anything that tells you how exactly, but if you haven't found any info about it by the time I get to my computer I can post some resource for this.
The signal would come out of the audio channels that usually are connected to speakers, but be careful about thinking about to what source you connect the audio output channel.
I am not certain but I would imagine that that output might be damaged relatively easily, but I may be wrong.
You can also acquire signals through the PCs sound card (mic).
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