A hissing or rumbling sound was sometimes reported. Whistling and hissing sounds are also sometimes heard but are poorly understood. They can make a few hissing or grunting sounds only heard when very close. The giant salamander is known to vocalize, making barking, whining, hissing, or crying sounds. Often accompanying the glow is a distinct hissing or buzzing sound. Gliders produce a number of vocalisations including barking and hissing. These images are accompanied by indistinct electronic buzzing and hissing sounds. Some languages have only a single hushing sibilant and no hissing sibilant. The bird is a close sitter, hissing and biting at an intruding finger. At times, these tentacles appear to be semi-autonomous, hissing and writhing like snakes. Cassowaries make a thunderous call during mating season and hissing and rumblings otherwise. However, some authors describe this display as being accompanied by loud hissing. Somewhat more common are languages with three sibilant types, including one hissing and two hushing. Many languages, such as English, have two sibilant types, one hissing and one hushing. Young birds have been heard making a hissing croak in flight.