Speaking and whistling with non-air gases

Whistling by humans after a deep breath of helium was observed to sound normal, with subsequent speech on the remainder of the breadth sounding strange. Inadvertent correction movements may have occurred, but effort was made not to shift any structures as the gas composition was changed. Large pressure changes do not make it difficult to speak but do somewhat change the sound composition. Human deep divers usually breathe a helium-oxygen mixture, which considerably changes the sound. However, a whistle language would not be ideal for divers. The effects of heavy gas at atmospheric pressure were also studied. An attempt was made to speak after a breath of SF/sub 6/, and the frequency was found to be lowered, the resonance being modified. However, the frequency of whistling did not change. Experiments were also tried with the very heavy gas perfluoropropane, with similar results. The voice took on a low pitch, while whistling was not changed.<>