A standard hearing test, known as an audiogram, does not directly measure the internal sound of tinnitus. Tinnitus is a symptom characterized by the perception of sound without an external source, and it is often closely linked to hearing loss. However, the audiogram provides essential information for diagnosis and management. Understanding what each assessment measures is the first step toward effective evaluation and treatment.
Understanding Tinnitus
Tinnitus is the experience of hearing sounds like ringing, buzzing, or hissing when no outside sound is present. It is a symptom of an underlying issue, originating from changes in neurological activity within the auditory pathways.
The vast majority of cases are subjective tinnitus, meaning only the patient perceives the sound. This type is usually associated with hearing loss, often due to noise exposure or aging. A far less common form is objective tinnitus, which is audible to a clinician during an examination, typically caused by vascular or muscular conditions. The subjective nature of most tinnitus explains precisely why a standard hearing test cannot detect the sound directly.
What a Standard Hearing Test Measures
A standard hearing test, or pure-tone audiometry, determines a patient’s hearing thresholds. This behavioral assessment measures the quietest sound level, expressed in decibels (dB), that a person can hear at specific frequencies (Hertz). The results are plotted on an audiogram, typically covering the frequency range most relevant to human speech (250 Hz to 8000 Hz).
The audiogram objectively identifies the degree and type of hearing loss, such as sensorineural or conductive. It does this by comparing air conduction thresholds with bone conduction thresholds. This assessment focuses on the ear’s ability to process external sound input, not the internal, self-generated neural activity that constitutes tinnitus.
Specialized Assessment for Tinnitus
Since the audiogram cannot quantify the internal sound, specific psychoacoustic procedures are employed to characterize the patient’s tinnitus. These assessments provide an objective quantification of the subjective sound.
Tinnitus Pitch and Loudness Matching
Tinnitus Pitch Matching determines the frequency of the tinnitus by having the patient compare their internal sound to external tones. High-frequency tones, often around 6000 Hz, are frequently matched, especially in cases related to noise-induced hearing loss. Tinnitus Loudness Matching determines the perceived volume by comparing it to an external sound of the same pitch. The subjective loudness is often surprisingly low, sometimes requiring only 10 decibels above the hearing threshold to match the volume.
Minimum Masking Level (MML)
The MML assessment finds the lowest intensity of a broadband noise required to completely cover, or mask, the tinnitus sound.
Tinnitus Handicap Inventory (THI)
These psychoacoustic measures do not capture the emotional impact of the condition. To assess the burden on daily life, standardized self-report tools like the Tinnitus Handicap Inventory (THI) are used. The THI is a 25-item questionnaire that scores the functional, emotional, and catastrophic effects of tinnitus, providing a measure of severity that guides treatment planning.
The Diagnostic Role of the Hearing Test
Although the standard audiogram does not directly detect tinnitus, it remains an integral part of the diagnostic evaluation. Its primary utility is identifying underlying audiological conditions that often cause the symptom. The pattern of hearing loss revealed frequently corresponds with the pitch of the perceived tinnitus, such as high-frequency loss being associated with high-pitched tinnitus.
Identifying specific hearing loss patterns, like those seen in noise-induced damage, helps clinicians narrow down potential causes and rule out serious conditions. The results are also instrumental in guiding treatment decisions. For example, they determine if a patient would benefit from a hearing aid with a built-in sound generator or other sound therapy options.