Year 8 Sound Flashcards
How is sound made ?
Vibrations / oscillation
What are some sources of vibration?
Vocal chords, the skin on a drum, strings on a cello, air inside/metal casing of a trumpet, the reed of an obo and the diaphragm of the speaker
What part of the ear vibrates?
Eardrum
How does sound travel from the source to our ears ?
Longitudinal sound waves
What is a longitudinal wave?
Longitudinal waves are waves in which the vibration of the medium is parallel to the direction the wave travels.
What happens to particles and air pressure when sound travel through the air?
They push and pull the air particles vibrate, left and right
What does compression mean?
It’s a region where the air pressure is higher than normal
What does rarefaction mean?
A region where the air pressure is lower than normal
Describe an experiment showing that sound travels as longitudinal waves.
The loudspeaker and candle demonstration.
The speaker is facing the candle and the speaker is turned on the candle will then flicker showing that longitudinal waves are present
Describe the Bell jar experiment
It shows if sound can travel through a vacuum.
It takes the air out from the jar, and a bell is inside a bit it keeps ringing, but as the particles are removed, there is nothing for the sound wave to travel through so you cannot hear the bell
What happens to sounds in a vacuum ?
Without Air particles, there can be no vibrations
Does sound travel faster through liquid solid or gas?
Solid because the denser the medium, the faster the sound travels
How do you measure the speed of sound?
S =d/t get two people far away from each other, and one person hits a block together. The other person sees them do this starts the stopwatch, and then when they hear the sound, they stop the stopwatch. 
What does Mach 1 mean ?
The sound waves cannot escape the noise of the jet
What happens when Mach 1 is exceeded ?
A sonic boom
How do you create an audible echo ?
The reflection f sound from a smooth hard surface
How do you measure the speed of sound using echoes ?
Stand a distance from a wall, hit wooden blocks and the person with the stopwatch starts it, they then hear the echo and stop it.
What are the uses of echoes ?
Sonar, lunar laser ranging and length of a steel rod and flaw detection
How do you perform standard echo calculations ?
S=2d/t
What is reverberation ?
Reverberation is created when a sound or signal is reflected.
What are the causes of reverberation?
Cathedral quires make use of this effect to make the music sound ethereal or heavenly
What is the definition of frequency?
The number vibrations per second
What is the definition of amplitude?
Maximum displacement of the vibrating medium from its equilibrium position 
How much frequency related to pitch ?
As the frequency of a vibration increases so does the pitch of the note
How much is amplitude related to loudness?
The larger the amplitude the louder it is
What is the range of human hearing?
20Hz-20kHz
How is the range of human hearing affected by age?
As you get older you’re ability to hear decreases
How does noise induced hearing loss affect ability to hear sound?
The worse the noise induced hearing loss is the less you can hear.
How do you minimise noise induced hearing loss?
You can use air protection, for example, headphones
What does a high frequency show on a CRO screen ?
The number of waves increases
What does a high amplitude show on a CRO screen ?
The taller the waves
