Investigation of the limits of the frequency range of hearing of gray seals Halichoerus grypus in an open-air constrain complex

During the experiment, the lower and upper limits of the frequency range of perception were studied in a group of gray seals kept at the Murmansk Marine Biological Institute of the Russian Academy of Sciences aquatic complex in Polyarny town (Murmansk Region, Russia), consisting of four 15-year-old females, three 5-year-old females, one 5-year-old male and two 8-month-old males. The studies were carried out in air and in water, at a depth of 2 m, at sound pressure levels of 60 and 90 dB (SPL). The results of the experiment showed that in the aquatic environment, the limits of perception in all the studied seals are higher than in the air, especially when perceiving high-frequency sounds, while the magnitude of the spread of values in the samples in adult females is significantly less than in 5-year-old seals and 8-month-olds, the latter have the largest spread. The relationship between the age of the studied seals and the frequency range of perception is revealed: with age, the range of perceived frequencies narrows and shifts to lower frequencies. It was found that a five-year-old male perceives lower frequencies in the study of the lower limit than the studied females of the same age. When studying the upper limit in the air, its threshold is lower, and in the water it is approximately equal to the indicators of females of the same age.