The spatial unmasking of pure tones by laboratory mice

The ability of animals to identify signals in their acoustical environment when confronted with sounds from multiple sources relies on them extracting the important information and filtering out background noise. Previous reports have shown that many animals are able to attend to a single sound more easily when that signal is spatially separated from the background noise. This spatial unmasking of a sound has previously not been behaviorally measured in mice, despite their use as a model for human hearing and communication. The present experiment examined if laboratory mice are able to show spatial release from masking, as seen in other animals, by testing the detection of 2, 4, 8, 12, 16, and 24 kHz pure tones in the presence of a white noise masker. The masker was spatially coincident with the signal or separated by 90°. We hypothesized that the mice would experience more spatial unmasking for the higher frequency tones since they rely heavily on these frequency ranges for their communication signals. Preliminarily, we have found that mice are able experience spatial unmasking at some, but not at all frequencies.