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.