Section 2 Flashcards
What is amplitude
The maximum displacement of the body from it’s position of equilibrium
What is peak to peak amplitude?
The maximum displacement in one direction plus the maximum displacement in the other. (Includes a compression and a rarefaction)
What will greater amplitude show on a sine wave?
Higher compression and greater displacement
What is the psychological correlate of amplitude?
Loudness
What is frequency?
The number of complete vibrations or cycles per unit of time. Measured in cps and expressed in Hz.
What is the frequency range of an average human?
20-20,000 Hz. Below this is infrasonic, and above this is ultrasonic.
How does mass affect frequency?
As mass increases, frequency decreases. As stiffness of a system increases, frequency increases.
What is resonant frequency?
The natural rate of vibration for a mass
Can all mass be set into a vibration other than it’s resonant frequency?
Yes, but when the force is removed, it will revert to it’s resonant frequency until it is damped.
What is the psychological correlate of frequency?
Pitch
Define period
The time elapsed during a single complete vibration
How does a period correspond with frequency?
They are reciprocals. A period= 1/f Low frequency sounds have a long period, high frequency sounds have a short period.
What is phase
Describes vibratory and wave motion when comparing waves- a cycle of a wave can be compared to a circular motion- 360 degrees is one wave cycle
What is a wave’s phase at equilibrium?
0
What is a wave’s phase at maximum compression?
90
What is a wave’s phase at 2nd equilibrium?
180
Does a wave’s starting phase always have to start at 0 in phase?
No.
What is velocity? How is it determined?
The speed at which sound travels. Determined by the density of the medium- more dense molecules have higher sound velocity- therefore, sound travels through a solid faster than through a liquid or gas. Reduced at higher altitudes and increased in higher temperature and humidity.
What is the velocity of air?
1130 ft/sec or 344 m/sec
What is wavelength?
The distance between two identical points on two adjacent waves- Wavelength is velocity of sound divided by the frequency (w=v/f)
As frequency increases, wavelength…
Decreases
What type of frequency has a short wavelength? What type has a long wavelength?
High frequency has short, low frequency has long
What is damping? What causes it? How does it relate to amplitude?
A reduction in amplitude over successive oscillations- when vibrations decay over time. Occurs due to friction and absorption of sound. Causes a decrease in amplitude over time, while frequency is unaffected.
If you know the wavelength of a pure tone, how could you solve for frequency?
f=c/w
What is free vibration?
When no outside force is perpetuating the vibration. Examples are tuning forks, pendulums, vibrating strings… It will vibrate at it’s own natural resonant frequency.
What is forced vibration?
An outside force controls the vibration of an object- vibration will continue until the outside force is removed.
What happens when a source of energy is removed from forced vibration?
Object will revert to free vibration until it is damped. Ex: human ear highly damped to avoid continuing vibration after a sound.
Is frequency affected by amplitude?
No.
What is the display of a sine wave waveform called?
Time-domain waveform
