The Origin of Sound & Sound in Air
Our subjective impression about the frequency of sound... A whistle makes a high _____ sound while a bass guitar makes a low _____ sound
What is pitch?
The frequency at which an object vibrates when it is disturbed (when it has enough elasticity and stiffness), producing a loud, sustaining sound
What is natural frequency?
What are vibrations?
As temperature goes up, the speed of sound...
Increases! Temperature and the speed of sound are proportional!
How is resonance produced in a vibrating object?
Sound waves with frequencies below 20 Hz (often too low for humans to hear)
What is infrasonic?
This type of vibration occurs when an object is made to vibrate by another vibrating object that is nearby
What is a forced vibration?
How does pitch relate to frequency?
They're proportional! As the frequency of an object's sound waves go up, the pitch of the sound it produces goes up as well (and vice versa)
Place the following mediums in order of the speed at which they conduct sound... gases, liquids and solids
1. solids (fastest)
2. liquids
3. gases (slowest)
Is it possible for one sound wave to cancel another?
Yes!
Sound waves with frequencies above 20,000 Hz (often too high for humans to hear)
What is ultrasonic?
An object that is forced to produce a magnified sound due to another object's vibration
What is a sounding board?
What is the average frequency range of a young person's hearing?
20 Hz - 20,000 Hz
What's the difference between sound intensity and loudness?
Sound intensity - objective, measured by scientific instruments
Loudness - subject, varies from person to person
What kind of interference happens when the crest of one wave collides with the trough of another, cancelling eachother out
What is destructive interference?
A pulse of compressed, high pressure air due to vibrating particles due to sound waves
What is a compression?
A phenomenon that occurs when the frequency of a vibration forced on an object matches the object's natural frequency resulting in an increase in amplitude
What is resonance?
Can sound travel through a vacuum (or in the absence of matter)?
No, sound requires a medium like air, water or steel to travel through
Why do different objects make different sounds when dropped on a floor?
They have different natural frequencies!
What kind of interference occurs when the crest of one wave collides with the crest of another, resulting in increased amplitude
What is constructive interference?
The pulse of low pressure air that happens when sound waves stop vibrating the air (returning to normal air pressure)
What is a rarefaction?
The periodic variation in the loudness of sound when two tones of slightly different frequency are sounded together (due to interference)
What are beats?
How fast does sound travel in dry air at room temperature?
340 m/s
Why do sounding boards make sound louder?
They provide more matter for vibrations
What is the beat frequency when a 500 Hz tuning fork and a 495 Hz tuning fork are sounded together?
500 Hz - 495 Hz = 5 Hz!