Procedures and intervention
During the first visit, a clinical history was taken. Also, the Montreal
Cognitive Assessment (MoCA) was applied [29,30] to guarantee no
previous cognitive impairment (based on normative scores for
hearing-impaired individuals [31]) and to exclude those individuals
who could possibly introduce bias into the results of the proposed
intervention. Hearing aids (receptor-in-the-ear, RIE) were then fitted
according to the previously performed randomization. The acoustic gain
prescription and the algorithms activated are described in Figure 1.
After the first fitting, microphone probe measurements were made so as
to ensure that both Groups A and B received at least 50% Speech
Intelligibility Index (SII) in speech mapping for weak intensity sounds
and at least 80% SII for medium-to-strong sounds. We activated the
premium and basic features as shown in Figure 1. Checks were also
carried out in Group C to ensure that the non-amplifying hearing-aid
(placebo) did not exacerbate auditory deprivation of these control
subjects. All participants were instructed on the use of the hearing
aids and were given the contact of the researchers to remedy any
problems arising during the use of the devices. After fitting the
hearing aids, part of the Brief Neuropsychological Assessment Instrument
was applied (NEUPSILIN) [32] to assess attention and memory
abilities (for further details on this neuropsychological test, please
read Fonseca et al., 2008 [33]). The patients we studied in this
protocol did not pay for any device or health service as it happens in
our health service which is financed by the Brazilian Public Health
System (named SUS).
At the end of the consultation, cortical auditory responses were
determined using a HEARLabĀ® device according to the protocol recommended
by Durante et al. [34] with speech stimuli (/m/, /g/ and /t/
at intensities of 55, 65 and 75 dB). Only latencies of P1 and N1 waves
were employed. At the end of that visit, the next visit was scheduled
(12 weeks later). During the period between the visits, the researchers
contacted the patients every two weeks to ensure that hearing aids were
being used properly.
Twelve weeks after the first visit, the participants returned to the
service and were reassessed using the same NEUPSILIN tasks. Cortical
auditory responses were measured again with the HEARLabĀ® device
according to the previously applied protocol. At the end of that visit,
participants completed the International Outcome Inventory for Hearing
Aids (IOI-HA), which investigated self-perceived usage, benefit,
residual activity limitation, overall satisfaction, residual
participation restriction, residual impact on others and quality of life
change [35].