412 



GENERAL SCIENCE 



32 vibrations 



128 vibrations 



512 vibrations 



2,000 vibrations 



4,000 vibrations 



40,000 vibrations 



per second produces the lowest musical sound. 



per second produces man's conversational voice* 



per second produces woman's conversational voice. 



per second produces high soprano. 



per second produces highest musical tones. 



per second produces highest audible sound. 



The Ear. Sound waves enter the ear, which has the right shape 

 to collect a large number of vibrations. Waves strike against the 



FIG. 307a. This diagram shows the inside of the ear, from the entrance to 

 the end of the nerve that passes to the brain. The drum is stretched 

 across the end of the canal, and on the other side is the chamber of the 

 middle ear, filled with air that enters from the throat. In this chamber 

 are three small bones, the hammer, the anvil, and the stirrup, the last 

 being fixed to the drum of the inner ear which is shaped like the coils 

 of a snail's shell. 



thin membrane called the tympanic membrane. To this membrane 

 are attached three little bones, the hammer, the anvil, and the stirrup, 

 which assist in transmitting the vibrations produced by the sound 

 waves through the middle ear to the cochlea. The cochlea is filled 

 with a liquid in which are stretched about three thousand filaments 

 of the auditory nerve. These little filaments vibrate sympathetically 



