INTRODUCTION
Population aging and its association with cognitive impacts of hearing
loss [1–5] is a growing concern. As people age, cognitive
dysfunction may manifest from mild to severe, including dementia itself
[6], which represents a public health concern [7,8] that might
be considered a priority for public health [8].
Hearing loss affects 23% of Americans who are 12 or older [9] and
is considered the main modifiable factor capable of preventing cognitive
decline in adult life [10]. As hearing is restored and the auditory
deprivation is reduced, the deleterious effects of hearing loss can be
prevented or attenuated, satisfaction with the use of hearing aids will
increase, and auditory brain response will improve [11–20]. Also,
despite the level of technology, both basic and premium hearing aids
performs similarly among those with mild-to-moderate hearing loss
[21,22]. Brazilian public health system, named SUS, freely provides
hearing aids for those who have a medical prescription to use them.
Depending on the level of technology, hearing aids present some special
sound processing strategies. The premium hearing aids typically include
more complex, automatic and adaptative version of the features, as well
as some features that are not available in the basic devices [23].
Among the features currently available are modern microphones,
transposing frequencies, and cancelling feedback, besides amplifying the
sound. Over the past years, both hardware (such as microphones) and
software (directionality, noise reduction and such) have been evolving
to a point in which microphones can adopt spatially dependent
directivity pattern. Also, natural directivity that works as
pinna-simulation directivity is an algorithm that seems to improve SNR.
The premium hearing aids we used in this study accounts for all these
features. More details on directionality, noise reduction, and sound
processing algorithms can be found in some theorical books [24–26].
Although previous research have shown that hearing aids may impact on
auditory brain response [20] and improve signal-to-noise ratio
significantly [21,22], none of them describes pragmatically the
hearing aids’ effect on poor educated individuals. Thus, we aimed to
compare, in a real-world scenario, the effects of different levels of
technology on attention, memory, electrophysiological response, and
self-perceived benefit of new users of hearing-aids in a developing
country such as Brazil.