Professionalism is key, especially if it worsens and the managers above end up getting involved. I've had to work with folk like that before both above and below me in the corporate hierarchy.
Offer them a chance to suggest an alternative approach, with reasoning. If they scoff at your 'Method A', simply politely ask them if they know of another solution. Nothing superior or disparaging on your part, something like "Not keen on this? If something's unclear, I can over it further. Or has an alternative come to mind?"
In this case, the scoffer may describe their 'Method B' without actually explaining why it is better. Again, sounding as if you are keeping an open mind can help. "Sounds good, we could give it a try. Does it do things faster than Method A? Is it easier to maintain or..."
I've worked with some people who (claim they) don't realise they are making these noises or reactions during discussions. Having an open-minded discussion about alternatives normally reduces the chances of the scoffing happening again or, which could be better, they are more forthcoming with their own suggestions. If worst comes to worst and the situation escalates, keeping the attitude described above means that you and your colleagues are in the clear; the only person displaying somewhat-aggressive behaviour was your superior.