From the Guidelines
To interpret an audiogram, one must analyze the graph showing a person's hearing thresholds at different frequencies, considering the symbols for each ear, the frequency and hearing level axes, and the patterns of hearing loss to determine the type, degree, and configuration of hearing loss, as outlined in the clinical practice guideline for age-related hearing loss 1.
Understanding Audiogram Components
The audiogram is a crucial tool in diagnosing and managing hearing loss, as emphasized in the clinical practice guideline: age-related hearing loss 1. It measures hearing sensitivity through air conduction and bone conduction, establishing the pattern of hearing loss at various frequencies. The guideline highlights the importance of distinguishing types and severity of hearing loss, which requires a comprehensive diagnostic evaluation including pure tone thresholds, speech audiometry, tympanometry, and acoustic reflex testing.
Interpreting Hearing Loss
Hearing loss is categorized based on the degree of loss: mild (26-40 dB), moderate (41-55 dB), moderately severe (56-70 dB), severe (71-90 dB), or profound (>90 dB), as generally accepted in audiology practice 1. The pattern of hearing loss across frequencies is also critical, with sloping loss often indicating age-related or noise-induced hearing loss, and flat loss suggesting conductive issues. The air-bone gap, which is the difference between air conduction and bone conduction, helps differentiate between conductive and sensorineural hearing loss.
Clinical Application
In clinical practice, understanding these elements of an audiogram is essential for guiding treatment options, as noted in the guideline 1. Pure Tone Audiometry (PTA) is considered the gold standard for detecting hearing loss and is a reliable tool for measuring hearing sensitivity. It can be repeated to monitor changes in hearing loss over time, informing diagnosis, symptom etiology, and appropriate treatment direction. Despite its utility, there are limitations to obtaining PTA, including workforce shortages and challenges in testing older adults with cognitive dysfunction, underscoring the need for accessible and adaptable diagnostic approaches.
From the Research
Interpreting an Audiogram
To interpret an audiogram, it is essential to understand the different components and how they relate to hearing loss.
- An audiogram typically displays frequency on the Y-axis and hearing level on the X-axis 2.
- The hearing level is measured in decibels (dB) and represents the minimum sound level that a person can detect.
- The frequency is measured in Hertz (Hz) and represents the pitch of the sound.
Types of Audiograms
There are different types of audiograms, including:
- Conventional audiograms: These are the most common type of audiogram and display the hearing threshold at specific frequencies 3.
- Three-dimensional audiograms: These display the duration of the disease on the X-axis, frequency on the Y-axis, and hearing level on the Z-axis, providing a more comprehensive view of hearing changes over time 2.
- Estimated audiograms: These can be obtained using machine learning techniques and provide a continuous threshold estimate as a function of frequency 4.
Relationship Between Audiogram and Tinnitus
Research has shown that there is a relationship between tinnitus pitch and the audiogram:
- Tinnitus pitch is often related to the frequencies of hearing loss 5, 6.
- Individuals with tone-like tinnitus tend to report a higher pitch than those with noise-like tinnitus 6.
- The edge frequency of the audiogram may be related to tinnitus pitch, but this relationship is not always clear 5, 6.
Estimating Audiograms
Audiograms can be estimated using different methods, including:
- Bayesian active learning: This method uses a Gaussian Process for classification and maximum-information sampling to determine the frequency and levels of the stimuli for the next trial 3.
- Machine learning: This method uses Bayesian estimation and machine learning classification to estimate a continuous threshold audiogram 4.
- Conventional audiometry: This method uses a modified Hughson-Westlake ascending-descending procedure to estimate the hearing threshold at specific frequencies 4.