A Hearing Aid from Phone-Grade Parts, Priced by Its Latency Budget

SIMULATED, NOT MEASURED. A latency-and-feedback budget for a phone-grade hearing aid at 48000 Hz, priced against a 10.0 ms comb-filter/own-voice limit and a 40.0 ms lip-sync limit. Only a wired low-latency configuration with foam tips passes both delay and gain tests (8.63 ms, 36 dB) for mild and moderate profiles; wireless configurations fail on transport delay. Best honest configuration costs $35.00 incrementally, runs 14.9 h under stated battery assumptions, and carries an assumption-bounded maximum-output warning (119.9 dB SPL, no certified limiter). No device was built, fitted or worn.