Humidity has a slight effect, the speed of sound being somewhat greater in humid air than in dry air. Since 1,129 feet is about one fifth of a mile, sound waves travel one mile in about five seconds. Thus you can tell how far away lightning is by counting seconds between its flash and the thunder and dividing by five. Many other substances are better conductors of sound than air. Like all gases, air is a poor medium for sound waves.
Sound waves travel in much the same way in liquids and solids as in air.
The molecules of a liquid move about less freely than do molecules of a gas, and the molecules of a solid less freely still. Compression waves, however, are formed and transmitted in them just as in air. In a good conductor, sound not only travels faster but also travels farther before it dies away. A few solids are much poorer conductors of sound than air. Rubber, cork, cotton, and felt, for example, tend to absorb sound waves rather than transmit them.