Why do I especially hate the sound of the bench grinding the floor?

Stick a cushion under the leg of the bench and it will be solved. Just try it. When students hear noise, they will be agitated and unable to study with peace of mind. This is what you call physiological reaction: when you hear the sound of a bench rubbing against the floor or nails rubbing against the blackboard, you will feel numb in your back and scalp, which is particularly uncomfortable. I've been particularly sensitive to this recently. If this continues, it will really affect the metabolism of brain cells, but students will also affect their academic performance.