Chapter 11- Sound

Sound waves
are compressional waves (which are made up of compressions and rarefactions); must have a medium to travel through; travels slowest through gas, fastest through solids; travels faster when the temperature is higher
outer ear
the visible part of the ear, the ear canal, and the eardrum; gathers sound waves and directs them to the eardrum
middle ear
3 small bones of middle ear-hammer, anvil, and stirrup; they amplify the sound waves
inner ear
the sound waves are converted to nerve impulses in the cochlea; the brain interprets the nerve impulses
spiral-shaped, fluid-filled structure in the inner ear that converts sound waves to nerve impulses
the amount of energy that flows through a certain area in a specific amount of time; influences how far away a sound can be heard; a sound wave of low intensity loses its energy more quickly and travels a shorter distance
tight, dense compressions in a sound wave
mean a high intensity, loudness, and more energy
the human perception of sound intensity
unit for sound intensity; abbreviated dB
how high or low a sounds seems; related to the frequency of the sound waves (like the notes on a music scale-do re mi fa so la ti do); becomes higher as the frequency increases
a measure of how many wavelengths pass a partaicular point each second; as the frequency of a sound wave decreases, the pitch becomes lower; people can hear frequencies from 20Hz to 20,000Hz, but humans hear frequencies best in the 440Hz to 7,000Hz range
high frequency sound waves
have closer compressions and rarefactions and a higher pitch than those of low frequency
sound waves with frequencies above 20,000Hz; can be used for medical purposes
infrasonic or subsonic
sound waves with frequencies below 20Hz
Doppler effect
change in pitch or frequency that occurs when a source of a sound is moving relative to a listener; can be used for other types of waves (not just sound) for example--police use radar in radar guns to measure speed
sounds that are deliberately used in a regular pattern
natural frequencies
every material has a set of natural frequencies at which it will vibrate
the process by which an object is made to vibrate by absorbing enery at its natural frequencies
sound quality
the difference between sounds having the same pitch and loudness
vibration whose frequency is a multiple of the fundamental frequency
hollow air-filled chamber that amplifies sound when the air inside it vibrates
the interference of two waves with different frequencies
the study of sound; scientists and engineers work to control the quality of sound in certain spaces
the echoing effect produced by many reflections of sound
the process in which objects are located by emitting sounds and interpreting sound waves that are reflected back
system that uses the reflection of sound waves to detect objects underwater
ultrasound in medicine
can detect and/or monitor certain medical conditions; can be used to cure problems such as kidney stones or gallstones