Acoustics - Statistical distribution of hearing thresholds related to age and gender
2Expert Interpretation
The ISO 7029:2017 standard details the impact of age and gender on the statistical distribution of hearing thresholds, providing expected median and dispersion data for people aged 18-80 in the frequency range of 125Hz to 12,500Hz. It is suitable for occupational noise exposure assessment and clinical audiology research.
Standard Overview and Technical Background
ISO 7029:2017 is the third edition of the audiology standard published by the International Organization for Standardization. It aims to quantify the impact of age and gender factors on the statistical distribution of hearing thresholds.
For the frequency range of 125-8000 Hz, the median hearing threshold deviation ΔHmd,Y at age Y is calculated as follows:
ΔHmd,Y = αmd ×
For the frequency range of 125-8000 Hz, the median hearing threshold deviation ΔHmd,Y at age Y is calculated as follows:
ΔHmd,Y = αmd × (Y - 18)βmd
Where αmd and βmd are sex/frequency related parameters (see Table 1 for examples):
| Frequency (Hz) | Male αmd | Female βmd | ||
|---|---|---|---|---|
| 500 | 4.59×10-4 | 2.537 | 3.98×10-4 | 2.775 |
| 4000 | 3.40×10-3 | 2.325 | 7.37×10-4 | 2.660 |
Clinical Application and Implementation Recommendations
Assessment of Noise-Induced Hearing Loss
The standard data is used as "Database A" in ISO 1999 to separate age-related and noise-induced hearing loss. Typical Application Scenarios:
- Calculate the 90th percentile threshold for a specific age/gender group (Q=0.9)
- Compare the measured thresholds for an individual with the expected distribution
- Use the formula: ΔHQ,Y = ΔHmd,Y + k×su (when Q≤0.5)
Implementation Notes
| Limitations | Explanation |
|---|---|
| High-Frequency Uncertainty | Data for people over 70 years old in the 3000-8000Hz frequency band is for reference only |
| Individual Differences | It is impossible to accurately distinguish between age-related hearing loss and other factors |
| Instrument Requirements | A pure tone audiometer calibrated in accordance with the ISO 389 series must be used. |
Technological Evolution and Data Comparison
The main changes in the 2017 edition compared to the 2000 edition are:
- A general decrease in high-frequency thresholds (especially a weakened 4000Hz notch in men)
- Stricter data screening to exclude instrument errors and abnormal hearing data
- Added extended high-frequency data from 9000-12500Hz (measured using the HDA 200 over-ear headphones)
Typical age-related loss trend: The median threshold at 4000Hz for 60-year-old men is 20dB higher (standard deviation 18dB) than for 18-year-olds