A hearing test provides specific information about an individual’s ability to perceive sounds. Understanding these results can feel complex, but deciphering the data offers valuable insights into auditory function and guides discussions about next steps.
Key Components of Hearing Test Results
The audiogram visually represents how well someone hears different pitches and volumes. The horizontal axis of this graph illustrates sound frequencies, or pitches, measured in Hertz (Hz). Lower frequencies, like 250 Hz, correspond to deeper sounds such as a dog’s bark, while higher frequencies, up to 8000 Hz, represent sharper sounds like a bird’s chirp.
The vertical axis of the audiogram indicates sound loudness, measured in decibels (dB). A 0 dB level does not signify the absence of sound, but the softest sound that a person with healthy hearing can typically detect. Sounds become progressively louder as the decibel numbers increase on the graph, ranging from very soft whispers to loud traffic noise.
Specific symbols are plotted on the audiogram to denote the softest sounds an individual can hear at each frequency. Circles typically represent responses from the right ear, while ‘X’ symbols mark responses from the left ear, both for sounds delivered through headphones (air conduction). Additional symbols, such as brackets, are used for bone conduction testing, which assesses the inner ear’s function directly.
Mapping Results to Hearing Levels
These plotted thresholds help categorize the degree of hearing sensitivity. Normal hearing is generally indicated by responses between 0 and 20 dB HL (Hearing Level). If thresholds fall between 20 and 40 dB HL, it suggests a mild hearing loss, making soft sounds or distant conversations difficult to hear.
A moderate hearing loss is indicated by thresholds ranging from 40 to 55 dB HL, making it difficult to follow conversations, especially in noisy environments. Moderately severe hearing loss, with thresholds between 55 and 70 dB HL, means many conversational sounds are missed.
Severe hearing loss, between 70 and 90 dB HL, implies that only very loud sounds are audible. Profound hearing loss occurs when thresholds are 90 dB HL or greater, meaning even very loud sounds are difficult to perceive.
Hearing levels often vary across frequencies. An individual might have normal hearing in low pitches but experience loss in higher pitches, affecting speech clarity.
Types of Hearing Loss Identified
Interpreting the relationship between air conduction and bone conduction thresholds on the audiogram helps identify the type of hearing loss. Air conduction testing evaluates the entire auditory pathway, from the outer ear through the middle ear to the inner ear and auditory nerve. Bone conduction testing, however, bypasses the outer and middle ear, directly stimulating the inner ear.
When air conduction thresholds are worse than bone conduction thresholds, and there is a significant gap between them, it indicates conductive hearing loss. This type of loss suggests a problem in the outer or middle ear that impedes sound from reaching the inner ear, such as earwax blockage or fluid behind the eardrum.
Conversely, if both air and bone conduction thresholds are similarly elevated, with no significant gap between them, it points to sensorineural hearing loss. This condition arises from issues within the inner ear, specifically the cochlea, or the auditory nerve. This type of hearing loss is frequently permanent.
Mixed hearing loss is diagnosed when both an air-bone gap exists and bone conduction thresholds are also elevated. This scenario suggests that problems are present in both the outer/middle ear and the inner ear or auditory nerve. Identifying the specific type of hearing loss helps in determining appropriate management strategies.
Beyond the Audiogram: Other Test Insights
While the audiogram provides a foundational understanding of hearing thresholds, a comprehensive hearing test often includes other evaluations. Speech audiometry, for example, assesses how well an individual hears and understands spoken words.
This includes measuring the speech reception threshold (SRT), the quietest level at which speech can be understood. Word recognition scores indicate clarity at a comfortable listening level.
Tympanometry is another common test that measures the function of the middle ear by assessing eardrum movement and middle ear pressure. This evaluation can identify conditions such as fluid buildup behind the eardrum, eardrum perforations, or issues with the tiny bones in the middle ear. Results are presented as a graph, showing eardrum compliance.
Otoacoustic emissions (OAEs) are soft sounds produced by the inner ear’s outer hair cells in response to auditory stimulation. Measuring OAEs can indicate healthy inner ear function, particularly the cochlea, and are often used in newborn hearing screenings or to evaluate the presence of sensorineural hearing loss. These additional tests provide a more complete picture of auditory health beyond pure tone thresholds.