Acoustic environmental and individual factors shaping human hearing sensitivity: assessing the relative impact of urban and rural soundscapes – EARSCAPE

Anthropogenic noise is still not considered a serious contaminant with an impact on human health. However, the prediction of the number of people who will be affected by hearing and non-hearing diseases in 2050 has been revised upwards by WHO: it has tripled in 3 years, from 700 million to 2.5 billion. While hearing loss, tinnitus and auditory fatigue are identified phenotypes, others such as hyperacusis (associated with attention deficit) or global early hearing loss in certain populations are underestimated and could have important social impact. It becomes urgent for public institutions, both national and local, to recognise that anthropogenic noise is a key source of disturbance for peoples’ health. The Earscape project explores, for the first time, whether the hearing sensitivity (HS) of normohearing individuals is shaped by acoustic environmental factors, and more specifically by the anthropophony component. We will use an innovative approach combining the expertise from ecoacoustics, hearing physiology, anthropology, population genomics and explainable artificial intelligence to unravel the complex interactions between acoustic environmental and individual factors. To reach our objectives, we will sample 9 human populations from 3 different geo-cultural areas (GCAs) and genetic backgrounds: Ecuador-Amazonia/Quechua, Gabon/Fang and France/French. For these 3 GCAs, we will develop a similar sampling scheme by selecting 3 soundscapes (Low-rural, Medium-rural, and High-urban) from inhabiting areas displaying variable levels of anthropization (i.e. sampling strategy is based on population density, lands take and the presumably associated level of anthropophony). This sample scheme will help to compare the different soundscapes within each GCA, but also to test for potential convergent process between rural and urban soundscapes. The soundscape of each population will be characterized using 1-year long ecoacoustic recording data; for the first time in this discipline, a precise measure of the anthropophony component will be developed. We will sample 270 individuals in the selected populations, collect their DNA and HS profiles using oto-acoustic emission. We will sample an equal ratio of men and women, a prerequisite for testing our scientific hypotheses. We will sequence their whole genome at 30x depth and analyse a set of 35 candidate hearing loss genes. We will explore both the genetic variants in coding sequences, as well as non-coding regulatory regions and associated CNV variants; the latter types of genetic variants being highly polymorphic, they are likely to retain the potential signature of ongoing local adaptation. All these data will be combined using explainable AI and machine learning procedures to reveal the relative impact of the different factors shaping hearing sensitivity. The results might lead to new paradigms on how, and by which mechanisms, the deep characteristics of our environment might influence the evolution of the hearing sensory traits. These results will open the discussion on the continuous adaptation of our hearing sensitivity to the current rapidly changing acoustic environment and especially on the potential maladaptive character of new forms of hearing sensitivity. Key information will be collected on rural and urban-specific soundscapes in human population, on population-specific global hearing loss and hyperacusis, on putative new genetic markers to consider in hearing loss genetic screening, and on the factors, ranked, affecting hearing sensitivity. Through an efficient scientific communication and the development of simple and efficient tools for the general public, we propose to increase awareness of hearing fragility.