title: COMMUNICATION AND SOUND TRANSMISSION IN HELIUM AND VARIOUS GASES AT REDUCED PRESSURES.
mesh_terms: D001274:Atmospheric Pressure; D003142:Communication; D005740:Gases; D006371:Helium; D009584:Nitrogen; D010100:Oxygen; D055585:Physical Phenomena; D010825:Physics; D012119:Respiration; D013016:Sound; D013026:Space Flight
chemical_list: D005740:Gases; D006371:Helium; D009584:Nitrogen; D010100:Oxygen
keywords: ATMOSPHERIC PRESSURE; COMMUNICATION; GASES; HELIUM; NITROGEN; OXYGEN; PHYSICS; SOUND; SPACE FLIGHT