Hearing Check — Methodology & Science

Important disclaimer: This is a screening tool, not a medical-grade diagnostic. Results depend on device volume, headphone type, and listening environment. Consult a licensed audiologist for a clinical assessment.

Tinni's hearing check is a pure-tone air-conduction screening using the Modified Hughson–Westlake threshold-search procedure — the same algorithm used in clinical audiology. It tests hearing sensitivity at 8 standard audiometric frequencies in each ear.

The Algorithm: Modified Hughson–Westlake

The Hughson–Westlake procedure was first published by Walter Hughson and Harold Westlake in 1951, then refined by Raymond Carhart and James Jerger in 1959. It is the procedure mandated by ASHA (American Speech-Language-Hearing Association) and international standards (ISO 8253-1).

The algorithm finds the minimum level at which a person can reliably hear a tone at each frequency by "bracketing" the threshold from above and below using an asymmetric step rule:

Threshold criterion: The lowest level at which the listener responds on ≥ 2 out of 3 ascending presentations.

We test 8 standard frequencies: 250, 500, 1000, 2000, 3000, 4000, 6000, and 8000 Hz. Roughly 12% of presentations are silent catch trials to detect guessing.

dB HL: the Hearing Level Scale

dB HL (decibels Hearing Level) is a relative scale:

All clinical audiograms are drawn with the Y-axis inverted (better hearing at the top, worse at the bottom). Tinni follows this clinical convention exactly.

The Hearing Number

The Hearing Number is the better-ear pure-tone average (PTA) at 500, 1000, 2000, and 4000 Hz. This 500–4000 Hz band is the "speech banana" — the frequency range that carries most of the acoustic energy of human speech.

This convention translates clinical PTA data into a single consumer-legible number on a familiar scale where lower = better.

Severity Tiers (ASHA Classification)

Tinni maps the better-ear PTA to ASHA's degree-of-hearing-loss categories (e.g., Normal, Mild, Moderate, Severe). Results are always labeled "Indicative" in the app.

References