If you're concerned that your colleagues are bothered, you should simply ask them. I'm sure everyone around you is aware that you have tics and cannot do much against them. But openly telling someone "Your constant humming is grating on my nerves" or even talking behind your back about your tics is bordering on discrimination.
However, if you breach that taboo and start talking about it, you give everyone the chance to talk civilized about their concerns, problems or acceptance. This not only applies to situations where you are so concentrated that you don't notice your tics, but also to situations that make you nervous and increase the frequency of your tics.
You could tell the colleagues sitting in your office after lunch break
Hey, I think you all noticed that I have this humming tic. All this learning makes me tic quite often, so I wanted to know if anyone is bothered by it? I'm concerned I might break your concentration or grate on your nerves, so please tell me if it's affecting you negatively.
By openly speaking about your tics, you might increase your acceptance among your colleagues or teach them about autism and tics. Depending on their answers you might talk to your manager to initiate some changes like moving some colleagues to another room or getting a room to yourself.
In any way, you initiating the talk will hopefully prevent frustration in affected co-workers because they feel like it's unappropriate to raise the issue.