When I was 10 and in fifth grade, the teacher showed us something I’d never known.

It was an afternoon in early spring. Mr. Borup wanted us to hear a piece of music, which was not unusual. He walked over to the recordplayer, a low fidelity machine in the front right corner of the room, by the windows to the outside corridor and poinsettia hedge, and he set the needle into the record groove.

I don’t remember the tune. It sank in afterward that what was played wasn’t the point.

We all sat quietly while the record spun. He was an innovative and masterful teacher, and I don’t remember any big disruptions in his class ever, except laughter, in which he invariably joined.

When the music stopped, Mr. Borup walked to the phonograph, lifted the arm, and shut off the turntable. Then he surprised the class.

He said he’d been watching us while the music played. He reported that almost every one of us was looking toward the recordplayer. He commented that it isn’t necessary to watch the record in order to enjoy the music it makes.

That led to a discussion about how sight-oriented people are. And to a custom, in me anyway, of seldom looking at the source of good sounds.