Learning to localize sounds like a barn owl

The brain computes sound location from auditory spatial cues. Humans and barn owls can localize sounds with high accuracy, yet they rely on fundamentally different cue configurations shaped by their ear anatomy and neural circuitry. In humans, symmetrical ears provide interaural time and level differences for horizontal localization, while vertical localization depends primarily on high-frequency, monaural spectral cues generated by the pinnae. Barn owls, by contrast, possess asymmetrical ears and use binaural cues to localize sounds in both azimuth and elevation. Because auditory pathways are assumed to be tuned to the statistics of species-specific cues, it remains unclear whether humans can localize sounds using barn-owl-like spatial information. We addressed this by fitting human listeners with asymmetric ear molds that disrupted normal spectral cues and introduced elevation-dependent interaural level differences, while preserving interaural time differences. Participants wore the molds during daily life and were tested on sound localization using broadband, high-pass, and low-pass noise. Acute exposure to the molds severely degraded elevation localization, while horizontal localization remained largely unaffected. With prolonged exposure, elevation localization improved, but adaptation was limited. Crucially, improvement was strongest for broadband sounds. Because broadband sounds uniquely provide access to both low-frequency interaural time differences and high-frequency interaural level differences, this pattern indicates that listeners learned to use binaural cues to infer sound elevation. These findings demonstrate that the human auditory system can partially adapt to extreme barn-owl-like outer-ear acoustics. Binaural cues can be repurposed to support elevation localization, with effective learning requiring access to complementary spatial cues. Conceptual takeawayGive humans asymmetric barn-owl ears and they can learn to use them - but only partially. The auditory brain is flexible enough to reinterpret new ear shapes, yet is strongly constrained in how far it can relearn a fundamentally different auditory space.