Personalized hearing aid amplification to ameliorate tinnitus

Around 10% of the population suffer from tinnitus and in some cases their
quality of life can be adversely affected. In most cases tinnitus is associated
with hearing loss, and it might be triggered by related changes in the brain,
as it has been observed in several animal studies. At the same time,
deafferentation produced by acoustic trauma can lead to a decrease of
spontaneous firing rates in the auditory nerve. Since these changes are
observed after a reduced auditory input, it can be assumed that a sensory
restoration might reverse the process. Hearing aids increase the volume of
external sounds, improving the communication of users while helping to mask
tinnitus. Potentially, hearing aids also revert the abnormal brain activity
that could be originated by acoustic deprivation.
There is a lack of high quality evidence to support the clinical efficacy and
effectiveness of hearing aids for tinnitus (Hoare et al., 2014; Shekhawat et
al., 2013), especially when it comes to randomized controlled trials (RCTs).
Well-designed randomized controlled trials are necessary in tinnitus research
to provide the higher grade of evidence quality for treatment efficacy, as it
described in clinical guidelines (Tunkel et al., 2014).
There is an increasing interest in sound-based therapies for tinnitus treatment
(Henry and Meikle, 2000; Hobson et al., 2007)Previous studies suggested that
the perceived tinnitus pitch usually corresponds to frequencies where hearing
is impaired (König et al., 2006; Norena et al., 2002; Roberts et al., 2008).
The tinnitus literature has shown that masking is more likely to be achieved
when the frequency range of hearing aid amplification includes the tinnitus
pitch (McNeill et al., 2012).
There is a great need for further studies involving RCTs with hearing aids in
tinnitus patients, exploring different amplification schemes that are adjusted
to the individuals* tinnitus pitch.
Some evidence suggest that details of the sound amplification strategy in the
hearing aid are key in the success in suppressing tinnitus. Specifically, it
was suggested that the amount of amplification that the hearing aid provides at
the tinnitus frequency may be a determining factor. This study is designed to
compare three amplification approaches, whether amplification at the tinnitus
frequency is either increased, reduced, or at a standard pre-described level.

The main objective of this study is to conduct a double-blind randomized
control trial to assess the efficacy of 3 different amplification schemes of
hearing aids in tinnitus patients. The schemes will be adjusted to the
individual*s tinnitus characteristics to potentially optimize the outcome.

The project will consist of a randomized controlled trial, designed as a Latin
square balanced crossover study. The design is balanced to avoid undesired
carryover effects. Patients will be fitted with hearing aids using 3 different
amplification schemes over the total period of 3 months, testing each approach
for a month. Questionnaires and psychoacoustic measurements will be used to
assess the outcomes of each scheme. Comparisons will be drawn across schemes
and correlations across measurements will be made within subjects.

Each subject will be fitted with the 3 different amplification schemes in the
same model of hearing aids, switching scheme every month.

There is no known high risk associated with participation. The only risk
associated with participation is that, with one of the amplification
strategies, tinnitus might get worse, but this situation is temporal. Patients
experience changes in their tinnitus every month, week, and sometimes every
day, and this can be related to the therapy or to different factors, such as
stress levels or psychological status. The experiment is non-invasive in
nature. Potential benefits with one, two or the three schemes of hearing aids
are: better tinnitus maskability, reduction of tinnitus intrusiveness,
concentration improvement, help with habituation/adaptation to tinnitus and
placebo effect. The stimulus sound level using tinnitus pitch and loudness
matching will always be adjusted by the participant and it will never reach
uncomfortable levels. The duration of the trial is 13 weeks, which involves 5
visits to the lab of around 2 hours each, to change the hearing aids* features,
fill in questionnaires and perform psychoacoustic tests.