What could explain lights flickering during focused thought?

I’d start with ordinary causes that can be checked: a loose bulb, a failing fixture or switch, wiring issues, or a problem affecting several devices on the same circuit. If multiple lights or appliances are acting up, ask a qualified electrician to inspect them rather than treating it as a harmless quirk. Make a simple log of what happened, where, and whether anything else was running.

Good call getting a medical assessment, especially since you’re noticing changes in how sharp or loud sounds feel. That does not establish a brain problem, but it is worth describing clearly to a clinician, including when it began, how often it happens, sleep, stress, and any medication or substance changes. If symptoms suddenly become severe or you feel unsafe, seek urgent care.

For the electronics, try separating observation from interpretation. Note whether the flicker happens with one particular lamp, outlet, or appliance, and see whether someone else can observe it without being told when you expect it. Phones can start playback because of app settings, connected devices, or accidental controls, so checking those settings may help narrow that part down.

When you’re deeply focused, you may notice background sounds and small changes that would usually fade into the background. That could explain why the electrical hum feels more prominent without explaining every device issue. I’d keep both possibilities open, avoid drawing a firm conclusion from timing alone, and check the physical and health-related angles.