Asymmetric Noise-Induced
Noise-induced loss that is significantly worse in the left ear than the right, with a pronounced dip around 4 kHz on the left side. Common after occupational noise exposure or shooting sports where one ear faces the sound source. Hearing loss that differs noticeably between ears is worth having evaluated.
Summary
- Severity
- Mild33 dB HL
- Most loss at
- 4 kHz · 75 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
- 12dB
- Normal
- Right ear
- 5dB
- Normal
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 | 0 | 0 |
| 500 | 0 | 0 |
| 1k | 10 | 5 |
| 2k | 25 | 10 |
| 3k | 65 | 30 |
| 4k | 75 | 35 |
| 6k | 55 | 25 |
| 8k | 30 | 15 |