Sforno on Genesis 42:7/ספורנו על בראשית מ״ב:ז׳

1ויכירם, he recognised them collectively as being his brothers, without being able to recognise who each brother was.

2ויתנכר אליהם, he adopted a manner totally uncharacteristic of him, by speaking arrogantly, masking his true voice, etc, apart from the fact that he spoke to them in Egyptian having everything he said translated into Hebrew by an interpreter.

3קשות, so that they would not recognise his voice.