1.13 Sound Waves & Hearing Flashcards
What are sound waves called by?
Vibrating objects
What are sound waves?
Vibrations that pass through the molecules of a medium
Are sound waves transverse or longitudinal waves?
Longitudinal
How are the vibrations passed through the surrounding medium?
These vibrations are passed through the surrounding medium as a series of compressions and rarefractions
What is meant by the compressions of vibrations?
Regions where the vibrating particles are closest together
What is meant by the rarefractions of vibrations?
Regions where the particles are furthest apart
How does a sound wave travel through a solid?
When the sound wave hits a solid object, the air particles hitting the object (the pressure) causes the particles in the solid to move back and forth (vibrate). These particles hit the next particles in line and so on - passing the sound wave through the object as a series of vibrations. As this happens over and over again, the sound wave is transmitted through the material.
Do sound waves travel faster in more densely packed materials or less dense?
More densely packed materials
Why do sound waves travel faster in more densely packed materials?
A higher density leads to more elasticity in the medium and hence the ease by which compression and rarefaction can take place.
Do the wavelength of sound waves get longer or shorter when it speeds up?
Longer
Do the wavelength of sound waves get longer or shorter when it slows down?
Shorter
What are sound waves reflected by?
Hard flat surfaces
What are echoes?
Reflected sound waves
Why can’t sound waves travel in space?
It is mostly a vacuum so there are no particles to move or vibrate
The ___________ of sound doesn’t change when it passes from one medium to another
frequency
What 3 things can sound be?
- Absorbed
- Refracted
- Reflected
What are ossicles in the ear?
A group of 3 small bones
Describe how human hearing works
Sound waves that reach your eardrum cause it to vibrate. These vibrations are passed on to tiny bones in your ear called ossicles, through the semi-circular canals and to the cochlea. The cochlea turns these vibrations into electrical signals which get sent to your brain. The brain interprets the signals as sounds of different pitches and volumes, depending on their frequency and intensity. A higher frequency sound wave has a higher pitch. Human hearing (audition) is limited by the size and shape of our eardrum, and the structures of all the parts within the ear that vibrate to transmit the sound wave
When the sound waves reach the cochlea, what happens next?
The cochlea turns these vibrations into electrical signals which get sent to your brain
What does the brain do after the sound waves get sent to it?
The brain interprets the signals as sounds of different pitches and volumes, depending on their frequency and intensity. A higher frequency sound wave has a higher pitch
What is another word for human hearing?
Audition
What is human hearing (audition) limited by?
The size and shape of our eardrum, and the structure of all the parts within the ear that vibrate to transmit the sound wave
What do the ossicles only work over?
A limited frequency range
What does a limited frequency range in the ossicles mean for humans?
Humans cant hear very low-pitched or very high-pitched sounds.
What range of frequencies do the ossicles in the ear transmit the most efficiently?
1kHz to 3kHz
What range of frequencies can young people usually hear?
20Hz up to 20 000Hz
What happens to the range of frequencies you can hear as you age?
The upper limit decreases, and sounds may need to be louder for you to hear them. This is mainly due to wear and tear of the cochlea or auditory nerve
Why does the upper limit of the frequency you can hear decrease as you get older?
This is mainly due to wear and tear of the cochlea or auditory nerve
What happens when sound waves travel from a less dense medium, to a more dense medium?
Their speed increases
The role of the ear drum is to:
Transmit the vibrations of the sound wave to the ossicles
The role of the auditory nerve is to:
Transmit the electrical signals from the cochlea to the brain
The range of human hearing is approximately ___ Hz to 20,000 Hz
20
The role of the cochlea is to:
Convert the vibrations into electrical signals
