Noun
aizuchi; backchanneling; interjections indicating that one is paying attention
かくかくしかじかで、と事情を説明したのだが、あんまり興味なさそうな相槌しか返ってこなかった。I explained the situation, as this, that and such and such, but they just nodded along without showing much interest. two smiths hammering at an object in turn
see 向こう鎚
Also written 相づち【あいづち】、相鎚【あいづち】