From the Guidelines
To calculate audiogram test results, you need to determine the pure tone average (PTA), which is the average of hearing thresholds at 500,1000, and 2000 Hz frequencies, as stated in the clinical practice guideline for age-related hearing loss 1. The calculation involves adding the decibel (dB) values at these three frequencies and dividing by 3. For example, if a patient's thresholds are 30 dB at 500 Hz, 40 dB at 1000 Hz, and 50 dB at 2000 Hz, the PTA would be (30+40+50)/3 = 40 dB. Some key points to consider when calculating audiogram test results include:
- The PTA helps classify hearing loss severity: normal hearing (0-25 dB), mild loss (26-40 dB), moderate loss (41-55 dB), moderately severe loss (56-70 dB), severe loss (71-90 dB), and profound loss (>90 dB) 1.
- The speech reception threshold (SRT) should be calculated and compared to the PTA; they should be within 10 dB of each other for a valid test.
- Word recognition scores are also important to assess how well a person understands speech at comfortable listening levels.
- Comprehensive diagnostic testing should include the measurement of pure tone thresholds, speech audiometry, tympanometry, and acoustic reflex testing, as recommended in the clinical practice guideline for age-related hearing loss 1. The PTA is considered the gold standard for detecting hearing loss and is a reliable tool used to measure hearing sensitivity through 2 pathways, bone conduction and air conduction 1. It is essential to note that there can be limitations with obtaining PTA, such as critical workforce shortages in the United States, and testing variations can influence the results, with standard diagnostic test-retest variability in adults fluctuating typically by ±5 dB across frequencies 1.
From the Research
Calculating Audiogram Test Results
The method for calculating audiogram test results involves several steps, including:
- Obtaining air-conduction thresholds for each ear at specific frequencies (e.g., 250,500,1000,2000,4000,6000, and 8000 Hz) 2
- Calculating pure-tone averages (PTAs) for specific frequency ranges (e.g., 0.5-2 kHz, 0.5-3 kHz, and 4-6 kHz) 2, 3
- Comparing the obtained thresholds to age-adjusted norms to determine hearing abnormality or loss 2
- Using specific criteria to define hearing abnormality or loss, such as a threshold greater than 10 dB above the norm for any PTA or greater than 20 dB above the norm for any individual frequency 2
Factors Affecting Audiogram Results
Several factors can affect audiogram results, including:
- Presbycusis (age-related hearing loss), which can be accounted for using age-adjusted norms 2
- Noise exposure, which can cause hearing loss and affect audiogram results 4, 5
- Background noise, which can significantly impact speech discrimination scores in individuals with sensorineural hearing loss 5
Estimating Numerical Thresholds from Audiograms
Machine-learning models, such as the Feature-Based Audiogram Value Estimator (FAVE), can be used to estimate numerical threshold values from scanned images of handwritten audiograms 6