The astronaut explained why it is impossible to whistle in a spacesuit

To whistle in a spacesuit during a spacewalk is not obtained due to low pressure, said canadian astronaut Christopher Hadfield.

"The air is too thin at a pressure of 4.3 pounds per square inch (220 mm Hg. — Approx. ed.)" — he wrote on his web page, answering a question of the subscriber.

The pressure in the suit is low specifically to ensure that the astronaut is easier to work with it.

Hadfield made three space flights, including two on the American Shuttle Orbiter with the Russian space station "Mir" and ISS, and the Soyuz spacecraft with a long stay at the international station. He performed two spacewalks.