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Many songbirds use the earth's magnetic field as a guide during their migrations, but radiowaves interfere with this ability. A new study has found an upper bound for the frequency that disrupts the magnetic compass. While radio waves emitted by radio and television broadcasting and CB radio can disrupt the magnetic compass of migratory birds, those used in mobile communication networks do not because the frequencies are too high to affect their sense of orientation. This was the key finding of a new study published in the scientific journal Proceedings of the National Academy of Sciences (PNAS) by a team of researchers led by Professor Dr Henrik Mouritsen of the University of Oldenburg and Professor Dr Peter Hore of the University of Oxford (UK). This finding also bolsters the researchers' theory that the magnetic compass sense in these birds is based on a quantum-mechanical effect (known as radical pair mechanism) located in their eyes. For this study, the team combined behavioural experiments with complex quantum-mechanical calculations on a supercomputer. Mouritsen, Hore and colleagues had already demonstrated in 2014 that electrosmog (human-made electromagnetic noise) in the AM radio waveband, such as that generated by household electrical appliances, impairs migratory birds' ability to use the Earth's magnetic field for orientation (known as magnetoreception). They posit that this weak electrosmog, which is harmless for humans, affects the complex quantum-physical processes in certain cells in the retinas of migratory birds which enable them to navigate with the help of the Earth's relatively weak magnetic field. But whether electrosmog also affects free-flying birds such as long-distance migratory birds, whose numbers have been declining for some time for unknown reasons, remains unclear. A light-sensitive protein called cryptochrome In the current study, the researchers took a closer look at the connection between the quantum-mechanical mechanism which they suspect forms the basis for the birds' magnetic sense and the disruption of this mechanism by radio waves. Their aim was to find further evidence of how the magnetic compass sense functions and thus provide a basis for further investigations into disruptive effects on the birds' migratory behaviour. The focus of their interest was the cut-off frequency above which the navigation of migratory birds remains unaffected, since determining this value allows conclusions to be drawn about the properties of the actual magnetic sensor in the birds. Their theory is that this sensor is a light-sensitive protein called cryptochrome 4 which possesses the necessary magnetic properties. The scientists' initial theoretical prediction was that the cut-off frequency would lie somewhere between 120 and 220 megahertz in the Very High Frequency (VHF) range, so the team conducted behavioural experiments with Eurasian blackcaps using different frequency bands within this range. In a study published in 2022 the researchers had already demonstrated that radio waves of a frequency between 75 and 85 megahertz interfere with the magnetic compass sense of these small songbirds. These experiments showed that their magnetic compass stopped working when they were exposed to these radio frequencies, but worked properly without exposure. Blackcaps are long and medium-distance migrants that can cover long distances during their annual migration High frequency radio waves did not affect the compass sense In the current study, a team led by Mouritsen and Hore as well as the two lead authors -- biologist Bo Leberecht and chemist Siu Ying Wong, both from the University of Oldenburg -- conducted experiments with frequencies between 140 and 150 megahertz and between 235 and 245 megahertz. They found that the radio waves in both these frequency bands did not affect the birds' magnetic compass sense -- which confirmed the scientists' theoretical predictions. The researchers also performed model calculations in which they simulated the quantum-mechanical processes inside the cryptochrome protein. On the basis of these calculations they were able to narrow down the cut-off frequency even further, to 116 megahertz. According to the simulations, radio waves above this frequency would only have a weak effect on the birds' magnetic orientation. This prediction was borne out by the results of the experiments. "Our experiments, together with detailed theoretical predictions, provide strong evidence that the compass magnetoreceptor in migratory birds is based on a flavin-containing radical pair and not a completely different sort of receptor, for example one based on magnetic nanoparticles," Mouritsen explains. Mobile communications networks do not impair the birds' magnetic sense Gaining a better understanding of magnetoreception is important for improving the protection of migratory birds. It can provide insights on key questions, such as what kind of electromagnetic radiation drives birds off course and should therefore be avoided in areas like nature reserves where migratory birds stop to rest. Mouritsen underlines that whereas the radio waves used in radio and television broadcasting or CB radio play a decisive role in disrupting magnetoreception, mobile communications networks do not impair the birds' magnetic sense: "The frequencies used here are all above the relevant threshold." This research is a result of the Collaborative Research Centre (CRC) Magnetoreception and navigation in vertebrates: from biophysics to brain and behaviour, of which Mouritsen is the spokesperson. The CRC's international team includes researchers from a wide range of disciplines including neurobiology, quantum physics, biochemistry, computer modelling and behavioural biology. In addition to the University of Oldenburg, the Institute of Avian Research "Vogelwarte Helgoland" (IfV) in Wilhelmshaven, the Freie Universität Berlin, the Ruhr University Bochum and the Weizmann Institute of Science in Rehovot (Israel) are also participating in the CRC. Three researchers from the University of Oxford (UK) are affiliated with the CRC as Mercator Fellows.

Researchers study the impact of hearing loss on subjects' enjoyment of different music mixes. They played different music mixes to listeners with and without hearing loss and found that those with hearing loss preferred louder lead vocals, higher frequencies, and sparser mixes with fewer frequencies overall. Previous research has found that music steadily shifted to quieter vocals and louder instrumentals leading up to 1975, meaning today's music may be less accessible to those with hearing loss. Millions of people around the world experience some form of hearing loss, resulting in negative impacts to their health and quality of life. Treatments exist in the form of hearing aids and cochlear implants, but these assistive devices cannot replace the full functionality of human hearing and remain inaccessible for most people. Auditory experiences, such as speech and music, are affected the most. In JASA, published on behalf of the Acoustical Society of America by AIP Publishing, researchers from the University of Oldenburg studied the impact of hearing loss on subjects' enjoyment of different music mixes. Modern pop or rock music is built from several individual tracks, such as vocals, instruments, and synthesized sounds, all recorded separately and mixed to make the final product. To cater to listener preferences, this mixing might entail raising or lowering the volume of one of the tracks or amplifying the high- or low-frequency sounds. "Mixing is tailored to suit the needs of normal-hearing listeners," said author Kai Siedenburg. "We wanted to explore whether there are actually differences in mixing preferences between normal-hearing and hard-of-hearing listeners." To do this, the researchers played different music mixes to listeners with and without hearing loss. They found that those with hearing loss preferred louder lead vocals, higher frequencies, and sparser mixes with fewer frequencies overall. "Generally, hard-of-hearing listeners have reduced frequency selectivity and impaired level perception," said author Aravindan Benjamin. "They tend to prefer louder levels of lead vocals compared to normal listeners." Previous research from the group has found that music steadily shifted to quieter vocals and louder instrumentals leading up to 1975 and has remained there, meaning today's music may be less accessible to those with hearing loss. Use of hearing aids can remedy these issues to a degree, but they are not available to many people with hearing loss and come with their own set of problems. Some users might prefer to adjust their music with software rather than listen to the default mix through hearing aids. "Getting good headphones, for example, and then playing around with the equalization might be a better approach than trying to squeeze everything through the hardware of the hearing aid," said Siedenburg. Ultimately, the biggest difference must come from the production side. Sound engineers with access to the individual tracks can make a big difference by making their work more accessible to millions of listeners. "One approach could be to offer a couple of different mixes, one for the general public and one for people who are moderately hard of hearing," said Siedenburg. "Certain adjustments to the mix might help to cater to the needs of this group of people in a better way."

Specific receptors in the ears of mosquitoes have been revealed to modulate their hearing, finds a new study. Scientists say, this discovery could help develop new insecticides and control the spread of harmful diseases, such as malaria. Specific receptors in the ears of mosquitoes have been revealed to modulate their hearing, finds a new study led by researchers at UCL and University of Oldenburg. Scientists say, this discovery could help develop new insecticides and control the spread of harmful diseases, such as malaria. The ability of male mosquitoes to hear female mosquitoes is a crucial requirement for their reproduction. As a result, the finding could help develop novel insecticides or mating disruptors to prevent mosquito-borne diseases like malaria, dengue, and yellow fever In the study, published in Nature Communications, the researchers focused on a signalling pathway involving a molecule called octopamine. They demonstrated that it is key for mosquito hearing and mating partner detection, and so is a potential new target for mosquito control. Male mosquitoes acoustically detect the buzz generated by females within large swarms that form transiently at dusk. As swarms are potentially noisy, mosquitoes have developed highly sophisticated ears to detect the faint flight tone of females amid hundreds of mosquitoes flying together. However, the molecular mechanisms by which mosquito males 'sharpen their ears' to respond to female flight tones during swarm time have been largely unknown. The researchers looked at the expression of genes in the mosquito ear and found that an octopamine receptor specifically peaks in the male mosquito ear when mosquitoes swarm. The study found that octopamine affects mosquito hearing on multiple levels. It modulates the frequency tuning and stiffness of the sound receiver in the male ear, and also controls other mechanical changes to boost the detection of the female. The researchers demonstrated that the octopaminergic system in the mosquito ear can be targeted by insecticides. Mosquito mating is a bottleneck for mosquito survival, so identifying new targets to disrupt it is key to controlling disease-transmitting mosquito populations. Co-lead author, Dr Marta Andrés (UCL Ear Institute) said: "Octopamine receptors are of particular interest as they are highlighy suitable for insecticide development. We plan to use these findings to develop novel molecules to develop mating disruptors for malaria mosquitoes. "Because mosquito hearing is required for mosquito mating, it can be targeted to disrupt mosquito reproduction. And increased knowledge of mosquito auditory neurosciences could lead to the development of mosquito mating disruptors for mosquito control." Co-lead author, Professor Joerg Albert (UCL Ear Institute and University of Oldenburg) said: "The molecular and mechanistic complexity of mosquito hearing is truly remarkable. With the identification of an octopamine pathway we are just beginning to scratch the outer surface of the tip of an iceberg. "Future studies will without doubt deliver deeper insights into how mosquito hearing works and also provide us with novel opportunities to control mosquito populations and reduce human disease."