Ch.10.3 Flashcards
How is sound produced?
Sound is produced by the vibrations of objects.
What is frequency? What is the unit of frequency?
The number of vibrations per second made by a vibrating object; hertz (Hz)
The ___________________ an object vibrates, the ___________________ the frequency of the sound produced.
faster, higher
The ___________________ the tuning fork, the ___________________ the frequency, the ___________________ the pitch.
shorter, higher, higher
How is sound transmitted?
When an object vibrates in the air, it pushes on the surrounding air particles and causes them to vibrate.
What is a common misconception of how sound travels? What is the correct concept?
X — air particles travel to transmit sound
V — the vibrations of air particles travel to transmit sound
Sound can travel through ___________________, ___________________ and ___________________. In short, sound must travel through a ___________________ (plural: ___________________). Sound is transmitted through the ______________________________________ in these.
gases, solids, liquids, medium, media, vibrations of particles
Why can’t sound travel through a vacuum?
This is because in a vacuum, there are no particles to transmit sound.
Why does sound travel the fastest in solids? Why does sound travel the slowest in gases? Name the order of the fastest to the slowest media in which sound can travel in.
This is because the particles in solids are close together and can pass along the vibrations quickly. Sound travels slowest in gases because the particles in gases are far apart and pass along the vibrations slowly. solids —> liquids —> gases.
The ear is the ___________________ for hearing. It can be divided into ___________________ sections: ____________________________________________________________________________.
sense organ, three, the outer ear, the middle ear and the inner ear
How do we hear? 1. 2. 3. 4. 5. 6.
- The pinna in the outer ear has a funnel shape. It collects sound from the surroundings and directs the sound into the ear canal.
- Sound travels down the ear canal to the middle ear.
- In the middle ear there is a thin membrane called the eardrum. The sound causes the eardrum to vibrate. The vibrations are transmitted to the ear bones.
- The three ear bones in the middle ear amplify the vibrations of the eardrum and transmit them to the inner ear.
- In the inner ear there is a coiled structure called the cochlea. Inside the cochlea there are sensory hair cells. These are specialised sensory cells that detect vibrations and produce signals.
- The signals from the sensory hair cells are sent to the brain through the auditory nerve. The brain then interprets these signals as sound.
Name the main organs of the ear and state where are they located: the outer ear, the middle ear or the inner ear.
outer: pinna, ear canal
middle: eardrum, three ear bones
inner: cochlea, auditory nerve, eustachian tube [[keeps air pressure balanced on both sides]]
Why can’t some people hear clearly? How can they improve their hearing?
Because their ear bones or the sensory hair cells in the cochlea do not function properly. They can use a fearing aid to amplify sound vibrations to help them hear better.
How do people who suffer from severe hearing loss improve their hearing? Describe it.
With a cochlea implant. It is implanted inside the patient’s ear by surgery. It converts sound into electrical signals which are sent to the brain.
There are ___________________ to our sense of hearing. Humans can hear only sounds of frequency from about _____________ Hz to about _______________ Hz. What is this range of frequency called?
limitations, 20, 20 000, the audible frequency range.
The audible frequency range ___________________ among different people. Eg: in general, the upper limit of hearing ____________________________________________________________________________.
varies, in a young person is higher than that in a older person
What does ultrasound refer to?
It refers to sounds of frequency above the audible frequency range of humans ( > 20 000 Hz)
Name two applications of ultrasound.
—Detecting cracks in welded metal objects such as steel pipelines
—Checking the condition of a foetus
Why can’t humans hear special whistles used for training some animals such as dolphins? Why can dolphins hear the whistle?
This is because it can produce sounds of frequency above 23 000 Hz, which is beyond the audible hearing range of humans. Dolphins can hear the whistle because they can detect sounds of frequency up to 100 000 Hz.
State the hearing ranges of bats, dolphins, dogs, birds, humans and elephants.
bats: 10-100 000
dolphins: 1000-100 000
dogs: 18-50 000
birds: 200-20 000
humans: 20-20 000
elephants: 5-12 000
What is noise?
Noise is any sound that is unwanted and disturbing.
In a busy city like Hong Kong, noise may come from ___________________, ___________________ ______________, ________________ _______________ or ________________ ________________, which can cause ___________________ ___________________.
traffic, construction work, human voices, loud music, noise pollution
What is the loudness of sound indicated by? What is the unit? What is used to measure sound levels?
Sound level, decibel (dB), decibel meter
-
85, the sound level, the duration of exposure
______________________________________ or ______________________ to ________________ ________________ may result in ___________________ (which is the __________________________________ in ears) or even hearing loss. Noise also causes other problems in daily life, such as _________________________________________________________ and _______________________________________.
Extremely high sound levels, prolonged exposures, loud sound, tinnitus, constant ringing in the ears, disturbing our study, work and sleep, causing mental stress
At 60dB, the harmful effects of sound are:
work and sleep disturbance and mental stress.
At 85dB, the harmful effects of sound are:
hearing damage begins (exposed for eight hours per day)
At 110dB, the harmful effects of sound are:
hearing loss (exposed for 15 minutes)
At 130dB, the harmful effects of sound are:
ears start to feel painful.
Name three sources of sound below 60dB.
normal conversation, whisper, leaf falling
Name a source of sound between 60-85dB.
Noisy street
Name two sources of sound between 85-110dB.
Heavy traffic, pneumatic drill
Name two sources of sound between 110-130dB.
Jet plane, disco music
Our sense of hearing allows us to _______________________________________________________________. We need to protect our sense of hearing because ________________________________________________________.
detect sound in the environment and communicate with one another, once it is damaged, it may not recover
Name four ways to protect our sense of hearing:
- Keep
- Shorten
- If
- Do
- Keep the volume low when listening to music using earphones
- Shorten the time you stay in a noisy environment
- If noise exposure is unavoidable, wear earplugs or ear protectors
- Do not pick your ears with hard objects
