Download Sound Notes and The Ear - CE Williams Middle School

509-513 in your Text
Define sound.
What part does each of the
following play in allowing you
to hear sound: outer ear,
middle ear, inner ear?
Sound Notes and The Ear
- sound - a disturbance that travels through a medium as a
longitudinal wave.
The ear consists of three basic parts - the outer ear, the
middle ear, and the inner ear. Each part of the ear serves
a specific purpose in the task of detecting and interpreting
sound.
Outer ear - Sound waves are gathered by the outer
ear made up of the ear, the ear canal, and the eardrum.
The outer ear is shaped to help capture the sound waves
(energy transferred in particles of air) and send them to
the ear canal, which transfers them to the eardrum. The
vibrations of air particles cause the eardrum to vibrate.
Middle ear - The middle ear amplifies sound waves.
Inner Ear - The inner ear transmits vibrations from
the bones of the middle ear to the liquid in the inner ear.
The tiny hairs in the inner ear vibrate as the liquid
vibrates. The vibrating tiny hairs transmit the energy to
nerves attached to the hairs. The nerve impulses are
transmitted to the brain for connections in the brain for
understanding of the sound as “hearing.”
Explain how sound is made
by a drum, guitar or your
voice.
*Examples of how sounds are made:
drum - as drum is struck, drumhead moves in and then out
creating compressions and rarefactions.
guitar - as guitar string is plucked it vibrates back and
forth creating vibrations, which create compressions and
rarefactions.
vocal cords - as you speak air is pushed up from the lungs
across the two folds of tissue, the vocal cords, causing
vibrations and then compressions and rarefactions.
Why can no sound be heard
in space?
What affects how loud a
sound is? What unit is used
to measure it?
What is the range of human
hearing? What are sounds
beyond this range called?
What is pitch? Give an
example of how pitch can be
changed.
* Sound can only travel if there is a medium, which is why
no sound can be heard in space.
- loudness - greater energy = greater amplitude = greater
intensity = louder sound. Measured in decibels (dB). Each
10 dB increase means an increase of ten-fold in intensity.
Sounds louder than 85 dB can cause pain and hearing loss.
* frequency is changed by muscles in the throat, affecting
the pitch of the voice. The higher the frequency, the
higher the pitch. Most people can hear frequencies
between 20 and 20, 000 Hz. Sounds of a higher frequency
of 20,000 Hz are called ultrasound. Those below 20 Hz are
called infrasound.
- pitch - the description of how high or low the sound
seems to a person. (pianos have a range of 27 - 4,186 Hz)
Summaries