[U6Q] When it is noisy, Hadir often bites his hand during cl…
When it is noisy, Hadir often bites his hand during class time, which results in his teacher removing him from the other students in the room. A new treatment protocol requires his teacher to put noise-canceling headphones on Hadir before starting instruction. Hadir bites his hand less during class time. The use of noise-cancelling headphones is an example of an: