What this does and doesn't measure
This finds the highest frequency you can hear at a fixed, comfortable volume — the number that falls with age as the tiny hair cells tuned to high pitches wear out. It does not measure hearing loss in the medical sense, which is about thresholds across all frequencies and needs calibrated equipment and a quiet booth, neither of which is your kitchen.
If you stopped hearing tones around 16 kHz: welcome to adulthood, that's typical. If speech sounds muffled or you're turning the TV up — different problem, real appointment.