Exam 2: 11 & 12 Flashcards
Sound
For the physical stimulus and a perceptual response
Physical Definition of sound
Sound is pressure changes in the air or other medium
Perceptual definition of sound
Sound is the experience we have when we her
“If a tree falls in the forest and no one is around to hear is there a sound”
Is there a sound ? yes. why?
If we are using a physical definition, because the following tree causes pressure changes whether or not someone is there to hear them
If a tree falls in the forest and no one is around to hear is there a sound”
Is there a sound? No. why?
If we are using the perceptual definition because if no one is in the forest there will be no experience
The piercing sound of the trumpet felt a room refers to what definition of sound
experience of sound aka sound perception
“The sound had a frequency of 1000 HZ” what is the definition of sound
Physical stimulus aka sound stimulus
What is it called when the movements or vibrations of an object has pressure changes in air water or any other elastic medium that can transmit vibrations
Sound stimulus
 when the diaphragm of the speaker moves out it pushes the surrounding air molecules together what is this process called
 compression which causes a slight increase in the density of molecules near the diaphragm. 
When the speaker diaphragm moves back in air molecules spread out to fill in the increase base what is this process called
Refraction. The decrease density of air molecules caused by refraction cause a slight decrease in air pressure
Speaker creates a pattern of alternating high and low pressure regions in the air is neighboring air molecules affect each other.
This pattern of air pressure changes which travels through the air at 340 m/s and through water at 1500 m/s
Sound wave
Think of a pebble dropping into is still full of water
As the ripple move outward from the pebble the water any particular place moves up and down the fact that the water does not move forward becomes obvious when you realize of the ripples would cause a toy boat to Bob up and down not to move outward. 
changes in air pressure occur in a pattern described by a mathematical function called a sine wave
Pure tones 
A person whistling or the high-pitched know it’s produced by flute or close to
Pure tones
Tuning forks which are designed to vibrate with a sign wave motion also produce
Pure tones
Vibration can be described by noting it’s number of cycles per second does a pressure changes repeat
Frequency
The size of the pressure change is called what
Amplitude
Hertz is the number of peaks per second/ frequency
Example from the board that had three peaks per second
Hertz has a perceptual dimension which is
Pitch
The volume of a sound is the
violence of the intensity of a sound (also known as
loudness or amplitude)
Pitch is what we
Perceive
The quality we describe as high and low think singing
Pitch
Volume is how tall the peak is
Loudness is the volume of a
Sound
Human hearing range
20 to 20,000 hertz
Audibility curve shows the threshold of hearing in relation to frequency
humans are most sensitive to 2,000 to 4,000 Hz.
Auditory response area: falls between the audibility curve and the threshold for feeling.
– It shows the range of response for human audition.
Equal loudness curves: determined by using a standard 1,000 Hz tone
Two dB levels are used: 40 and 80
Participants match the perceived loudness of all other tones to the 1,000 Hz standard. Resulting curves show that tones sound:
At almost equal loudness at 80 dB
Softer at 40 dB for high and low frequencies than the rest of the tones in the range
Threshold of feeling on graph db ( intensity) id the highest, what can this do to us
Cause ear damage, body vibration in club
Equal loudness curve
Conversation level
Audibility curve threshold
Threshold of hearing, cant hear below
all other perceptual aspects of a sound besides loudness, pitch, and duration
– It is closely related to the harmonics, attack, and decay of a tone.
Timbre
Effect of missing fundamental frequency
Removal of the first harmonic results in a sound with the same perceived pitch, but with a different timbre.
• This is called periodicity pitch.
The buildup of sound at the beginning of a tone
Attack of tones
Decrease in sound at end of tone
Decay of tone
Pinna and auditory canal are located in the
Outer ear
What does the pinna do
Help with sound location
Tube like structure 3cm long, protects the tympanic membrane at the end of the canal
Auditory canal
The resonant frequency of the canal amplifies frequencies between 1,000 and
5,000 Hz.
Auditory canal
Two cubic centimeter cavity separating inner from outer ear Contains the three ossicles
Middle ear
moves due to the vibration of the tympanic membrane
Malleus
transmits vibrations of malleus
Incus
transmits vibrations of incus to the inner ear via the oval window of the cochlea
Stapes
Functioning of ossicles
Outer and middle ear are full with air