Client calls. Average baby grand, average fairly bare hard surfaced large living room.
Client says there's a horrible "vibration" coming from the piano since I last tuned it (months ago, no issues then).
I come out, and there is NO problem. Client is mystified, swears they're not crazy, there WAS a HOOOOOOOOOORIBLE "vibration" coming from the soundboard when SHE plays. But not now.
I ask her how she knows it's coming from the soundboard, she says it gets louder the closer she puts her ears to it. Fair enough.
I tell her CALL ME WHEN IT HAPPENS AGAIN, she says OF COURSE.
She does, I come out, again NO PROBLEM.
The third time, I'm about to leave with no problem detected, listening to her play, and all of a sudden, a HORRIFIC STEADY WARBLING STARTS COMING FROM THE SOUNDBOARD. Fascinated, yep, got louder the closer I got to the soundboard. About 10 beats a second.
But I recognized that warbling. Ceiling fans over the piano. But I'd never seen a ceiling fan at that house or noticed any other static sound chopper upper thingy in the vicinity.
I asked her if we could tour the house, sure.
Since my last tuning, they'd built a greenhouse to grow orchids (lovely orchids!)
The greenhouse had a VERY large INDUSTRIAL fan for ventilation, on an automatic timer.
All surfaces in the house were smooth and hard and reflective, no carpets, only tiles and wood, and when she played, all the doors in the house were open, so sound could bounce around unimpeded.
Have you been in one of those special corridorish echo-y places where sound travels quite a distance quite intact?
Her whole house was one of those, and the piano sound waves were getting through that fan and get bounced back to her piano room.
She turned off the fan, saw that was the problem, looked embarrassed, and pays me $100 for each visit I'd made.