Students should be allowed to wear headphones, unless they're disruptive.
A few caveats:
Students should clearly grasp the material.
Students should check with the teachers to make sure it is okay to wear headphones. In a lecture environment, they had better be taking notes so they can answer the teacher's questions.
Students should not disrupt class with their headphones.
At an absolute minimum, students should be allowed headphones when taking tests, or an essay, or anything where there is little to no verbal interaction with anyone, unless forbidden by the teacher or proctor, especially in cases of the pSAT, SAT, ACT, any HSEE (High School Exit Exam), labs, or standardized testing.
Listening to music during the teachers lecture is going to limit the amount of information you are able to take in. How are you supposed to listen to music an the teacher at the same time. I know that I struggle listening to music and performing a different task at the same time, with a few exceptions. Most people start singing when they e to a song that the like. That is ditracting for the rest of the class, making it so that they can' focus either.
Multiple studies show that humans do worse at tasks when listening to music by-and-large. Some will do well but most will do lesser. Thing is doing "satisfactory" is frivolous as a base for discerning if it's viable or not s I cannot see how it could be encouraged considering the nature of the matter.