Option - Chapter 2 Flashcards
What type of waves are sound waves and what can they pass through?
Sound waves are longitudinal waves and they can pass through solid, liquid and gases.
How does a loudspeaker work?
The loudspeaker is connected to a signal generator. This will cause the diaphragm on the speaker to move. When it moves forward, it will compress the surrounding air slightly, pushing the surrounding air molecules into molecules further away which will push other molecules etc. When the diaphragm moves backwards, it expands the air so creating a low-density region, rarefaction, surrounding air molecules will move into this space. This will create vibrations creating sound waves of alternate compressions and rarefactions.
What is a note defined as?
A note of sound consists of sound waves that vary smoothly and rhythmically which makes them easy to listen to.
What is the normal range of frequency which the human ear can detect?
20Hz to 18000Hz
What does the outer ear consist of? And what do those parts do?
It consists of the pinna and the ear canal.
The pinna reflects sound waves into the ear canal.
What happens to the pressure waves as they hit the eardrum?
The pressure waves hit the eardrum which causes it to vibrate.
At what frequency is the ear most sensitive?
The ear is most sensitive at 3000Hz
What does the middle ear consist of and how are pressure changes equalised?
The middle ear consists of three bones, the hammer, anvil and stirrup. Pressure changes are equalised between the middle and outer ear by air flowing through the Eustachian tube.
What does the hammer, anvil and stirrup do?
They act as a lever system to amplify the force of the vibrations by about 50%, giving an increased force of X1,5.
They filter out noise generated by the body and protect the ear from excessive vibrations.
How do the hammer, anvil and stirrup react when in a quiet and loud environment?
Quiet - the muscles contract pulling the bones together, giving maximum effectiveness as transmitters of sound energy.
Loud - The muscles become lack allowing the bones to vibrate differently so they are less effective.
Why does temporary deafness occur after leaving a noisy environment?
Because it can take some time for the muscles in the ear to become taut again, bringing the three bones together.
Describe the events for a sound vibration which is passed through the inner ear naming all parts of the middle ear
It is a fluid filled enclosed cavity which receives the sound vibrations from the middle ear as its oval window. These vibrations are then transmitted through the fluid of the cochlea as pressure waves, making the basilar membrane vibrate, and then onto the round window where they leave the inner ear.
What does the Basilar membrane do?
The Basilar membrane is covered in lots of tiny sensitive hairs which send impulses to the brain as a result of being stimulated. At different frequencies, the hairs vibrate at different positions each pattern of vibration causing a pattern of nerve impulses which the brain learns to interpret.
What is the formula for pressure on the oval window?
Pressure on the oval window = (force on oval window/area of the oval window) / (force on eardrum/area of the eardrum)
Define the decibel scale?
It is a logarithmic scale which is used to measure the response of the human ear to changes of sound intensity.
