STRC-Related
Mild to moderate hearing loss due to changes in both copies of STRC, which makes stereocilin. It’s the leading genetic cause of mild to moderate loss, usually discovered during early childhood, and it tends to stay stable or change slowly. The outer hair cells, the cochlea’s amplifier, have hair bundles that don’t hold together or anchor in the membrane above them, so quiet sounds aren’t boosted, and the loss can grow over time. The inner hair cells and the nerve still work. Gene therapy is being developed for it but has only been tested in mice so far.
Summary
- Severity
- Moderate42 dB HL
- Most loss at
- 6 kHz · 50 dB
Degree of the worse ear, averaged over all eight frequencies, on the scale used by U.S. audiologists (ASHA)
Pure-tone average (PTA)
- Left ear
- 38dB
- Mild
- Right ear
- 38dB
- Mild
What’s a pure-tone average?
Pure-tone average is the quietest tone each ear can just hear, averaged across three pitches central to speech (500 Hz, 1 kHz, and 2 kHz). It’s the single number U.S. audiologists use to sum up an audiogram. 15 dB or lower is normal hearing, and every 10 dB higher means sounds need to be about twice as loud to be heard. Internationally, the World Health Organization averages four pitches, adding 4 kHz, so where high pitches have more loss its number comes out higher.
Thresholds by frequency
| Hz | L | R |
|---|---|---|
| 250 | 30 | 30 |
| 500 | 35 | 35 |
| 1k | 40 | 40 |
| 2k | 40 | 40 |
| 3k | 45 | 45 |
| 4k | 45 | 45 |
| 6k | 50 | 50 |
| 8k | 50 | 50 |