Hearing Screening with a Smartphone: An Error Budget and the Protocol It Permits

Smartphone pure-tone screening modelled with an explicit error budget: combined PTA standard deviation 4.126 dB in a quiet room (32 dBA) and 5.387 dB in a typical room (47 dBA) with model-specific calibration. A binary screen for moderate-or-worse loss (35 dB HL) is supported away from the boundary (false referral 0.1128 at true 30 dB HL in a quiet room; sensitivity 0.8868 at true 40 dB HL), exact WHO grade assignment is not supported, and in a typical room the 25 dB HL masking floor makes the normal-to-mild boundary unusable. A gated protocol is specified: 500-4000 Hz, 5 dB steps, ambient gate 35 dBA measured by the phone microphone, binary referral only. SIMULATED, NOT MEASURED.