Noise-Induced (4 kHz Notch)
A sharp dip in hearing around 4 kHz, the frequency range most vulnerable to loud noise. Common after prolonged exposure to gunfire, heavy machinery, or loud music. The rest of the hearing range may be relatively intact, which is why people with this pattern often do not notice it at first.
Summary
- Pure-tone average (PTA) · Left ear
- 7 dB
- Pure-tone average (PTA) · Right ear
- 7 dB
- Most loss at
- 4 kHz · 65 dB
- Severity
- Slight
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 typical 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.
Degree of the worse ear, averaged over all eight frequencies, on the scale used by U.S. audiologists (ASHA)
Thresholds by frequency
| Hz | L | R |
|---|---|---|
| 250 | 0 | 0 |
| 500 | 0 | 0 |
| 1k | 5 | 5 |
| 2k | 15 | 15 |
| 3k | 50 | 50 |
| 4k | 65 | 65 |
| 6k | 40 | 40 |
| 8k | 20 | 20 |