Page 36 - Winter 2020

PSYCHOACOUSTICS OF TINNITUS
reminded of that experience by the presence of the tinnitus, reinforcing in their mind that they cannot escape the tin- nitus nor escape or leave the past behind them.
Is There a Cure for Tinnitus?
Despite decades of research there is no “cure” for tinnitus. Indeed, no medication or surgery can remove the tinnitus perception from the brain. In the absence of a cure, medi- cal interventions focus on mitigating the tinnitus reaction. Treatment options generally include some form of counsel- ing (e.g., education on the neuroscience of tinnitus) and use of sound enrichment (e.g., hearing aids) to help diminish the tinnitus perception and reaction (Tunkel et al., 2014).
The most common side effects of tinnitus are sleep dis- turbances, concentration issues, loss of quiet/feeling of inability to escape the tinnitus, and emotional/stress-based issues (Tyler and Baker, 1983). Although rare, tinnitus can result in suicidal ideation and suicide (Szibor et al., 2019). It is also common for persons with tinnitus to attribute their hearing difficulties to their tinnitus perception (Henry et al., 2015). This is in general unsupported; tinnitus does not cause HL, but, rather, HL causes tinnitus. Nonetheless, tinnitus can affect concentration that can impact listening (Burns-O'Connell et al., 2019) and speech understanding with competing noise (Oosterloo et al., 2020).
Measuring Tinnitus in Humans
There is currently no widely accepted or validated method to identify the presence of primary tinnitus and quantifi- cation of its perceptual characteristics other than what is reported by the patient. An objective measure of primary tinnitus by the clinician, a long-held goal, is complicated by the relationship among tinnitus, HL, and hyperacusis (sound sensitivity related to increased central neural activ- ity compensating for reduced peripheral input) and a lack of sensitivity and specificity from electrophysiological measures or imaging studies. Developing objective mea- sures of tinnitus has been challenging in studies in both human and animal.
Then again, perhaps an objective measure to rule-in or rule- out the presence of tinnitus is not necessary. For example, the gold standard for assessment of hearing sensitivity is the pure-tone audiogram (Figure 1), which indicates the lowest sound level a human or animal can detect at different frequencies. The audiogram is, however, a psychophysical measure that is nonobjective in nature. Of course, a method
to measure tinnitus that has translation between animal models and humans would be most efficacious to empower development of diagnostic and treatment approaches.
Recommendations for the psychophysical assessment of tinnitus were postulated over 20 years ago by the Ciba Foundation and the National Academy of Sciences. Methods for administering the psychoacoustic battery for tinnitus assessment have been reviewed (Henry, 2016). To date, standardization of these procedures is still not rec- ognized; however, generalized clinical methods are briefly described here.
Pitch match (PM) measures the patient’s perceived tin- nitus pitch (perception of sound frequency) by matching the tinnitus to a specific frequency or range of frequencies. PM is typically measured, although crudely, using an audi- ometer where two sounds are played, and the person with tinnitus chooses the pitch closer to their tinnitus percept. Most patients with peripheral hearing deficits match their tinnitus pitch at frequencies respective to their HL.
Figure 1. Audiogram and tinnitus match. An audiogram is a graphical representation of hearing thresholds at different frequencies. The frequency of the signal is plotted against the level required for the patient to detect the sound stimulus. Gray bars, variable levels of hearing loss (HL). Levels less than 15 dB HL are considered normal hearing and greater than 15 dB HL corresponds to escalating levels of HL severity. This tinnitus patient (right ear only) has normal low-frequency hearing, sloping to a high-frequency HL or a moderate level. Red T represents the pitch and loudness match for the patient. In brief, this patient matched their tinnitus pitch at 4,000 Hz and loudness at 55 dB HL or 10 dB sensation level to their threshold (45 dB HL).
36 Acoustics Today • Spring 2021