My response to this, in discussions in DND and beyond (even into work and non-gaming social situations), is simple. If Bob has interrupted Alice:

Bob, Alice was speaking.

Or, if bob has interrupted me:

Bob, I was speaking.

Raise your voice (admittedly, it's easy for me, because I'm a very loud person), and put on your best firm teacher and/or mom voice. When a GM doesn't manage a session enough to stop this, sometimes you have to pipe up and put your foot down. The tone is key, here. You don't want to sound either angry or whiny, because if the attention hog is actually malicious, they will likely turn that on you. A firm voice and a neutral, but accurate, statement normally does the trick for me.

If you are worried about being overly harsh or too authoritative, qualifiers work wonderfully:

Hey, Bob, I think Alice was speaking?

while still getting the point across.

My response to this, in discussions in DND and beyond (even into work and non-gaming social situations), is simple. If Bob has interrupted Alice:

Bob, Alice was speaking.

Or, if Bob has interrupted me:

Bob, I was speaking.

Raise your voice (admittedly, it's easy for me, because I'm a very loud person), and put on your best firm teacher and/or mom voice. When a GM doesn't manage a session enough to stop this, sometimes you have to pipe up and put your foot down. The tone is key, here. You don't want to sound either angry or whiny, because if the attention hog is actually malicious, they will likely turn that on you. A firm voice and a neutral, but accurate, statement normally does the trick for me.

If you are worried about being overly harsh or too authoritative, qualifiers work wonderfully:

Hey, Bob, I think Alice was speaking?

while still getting the point across.