Biology subjects

Jurado, C.

Publications and source records attributed to Jurado, C..

2 recordsLinked to original sources

bioRxiv2025

On the potential sources of a low-frequency sound percept only a few can hear

A small percentage of the general population reports almost constant humming or pulsing low-frequency sound percepts (LFSPs) while others in their vicinity, such as family members, often do not perceive these sounds. The origin of these LFSPs remains to be elucidated and may or may not be related to external sound sources. The underlying causes of these perceptions could also be subjective and belong to the tinnitus family, especially in cases where no external sound source sufficiently explaining the LFSP can be found. The present study puts forth two hypotheses to explain the phenomenon, based on both subjective and objective auditory phenomena: an unusually high auditory sensitivity to low-frequency sound, and hearing ones own low-frequency spontaneous otoacoustic emissions (SOAEs), sounds actively produced by the inner ear as a normal, physiological by-product of cochlear amplification. The present study employed high-resolution, low-frequency hearing threshold measurements and SOAE measurements in 28 individuals with LFSPs, and in control groups devoid of LFSPs. LFSP complainants self-reported hearing a LFSP at a median frequency of 50 Hz obtained with a frequency-matching procedure. With a few clear exceptions, complainants most often did not present unusually sensitive low-frequency hearing thresholds. Furthermore, hearing threshold fine structure was comparable to the control group. In addition, no SOAEs in the low-frequency range could be measured. Based on our results, while cases of hearing physical external sound sources are not ruled out, we suggest that a subjective tinnitus in the low-frequency range is often the reason behind hearing these LFSPs.

biophysics↗

bioRxiv2025

Advancing ecological assessment: The integration of eDNA metabarcoding into an estuarine fish index

In the face of increasing anthropogenic pressures on estuarine ecosystems, methods to efficiently and reliably assess their ecological status are essential. This study explores the integration of environmental DNA analysis into the AZTIs Fish Index (AFI) to assess ecological status of estuarine ecosystems. Surface water eDNA sampling and bottom trawl surveys were performed across multiple estuaries in the Basque Country, Spain, and resulting species data were used to calculate AFI scores. eDNA metabarcoding consistently detected higher fish species richness than bottom trawling, while the latter remained more effective at capturing demersal species. In general, ecological classifications from eDNA- and bottom trawl derived data displayed low concordance, largely due to differing species assemblages and metric contributions. These results emphasize the respective strengths and weaknesses of each methodology and the necessity for method-specific calibration. Considering that the AFI is calibrated using bottom trawl data, its direct application to eDNA-derived species lists may lead to some inconsistencies. This study underscores the critical necessity to establish eDNA-specific reference conditions and to recalibrate index thresholds accordingly. While eDNA approach may not entirely replace traditional methods, its scalability, sensitivity, and minimal ecological disturbances establish it as an essential complementary application within estuarine assessment programs. This research strongly supports the urgent advancement of eDNA-based indices and the critical enhancement of reference conditions for their effective incorporation into ecological assessment frameworks under the Water Framework Directive.

ecology↗