Antiheckler Technique

In Feeling Good: The New Mood Therapy Revised and Updated, David Burns presents his technique for dealing with hecklers:

Immediately thank the person for his or her comments.

Acknowledge that the points brought up are indeed important.

Encourage that there is a need for more knowledge about the points raised,
and encourage your critic to pursue meaningful research and investigation of
the
topic.

From experience, I've seen speakers effectively take the wind out of their heckler's sails using this approach. Alternatively, taking a defensive posture tends to fuel a heckler's fire.