Echo cancellation on megaphone using ADAU1761

I am developing a megaphone using ADAU1761. The structure is as in the attached image.
However, when the output level is raised, the howling is severe. I've searched various QnA related to echo cancellation to solve this problem, but couldn't find an exact answer or example.
1) I wonder if howling can be controlled using NLMS of ADAU1761.
2) If possible, please share an example of how to connect and use NLMS to do this.

Audio Signal Processors

SigmaDSP Audio Processors

adau1761