Noise Flashcards
_____ is the vibration of air molecules
sound
____ is sound pressure perceived as loudness
amplitude
_____ = cycles per second (hertz) perceived as pitch
frequency
What range of amplitude and frequency can you hear?
Amp = 0.00002-20N/m^2 Freq = 16-20,000 Hz
How do air particles vibrate?
about a fixed point - go from condensation –> rarefaction - a wave of vibration spreads outward
Sound waves enter the outer ear and travel through the ___ ____ to the ____ (aka?)
ear canal; eardrum (tympanic membrane)
the eardrum vibrates and sends vibrations to three tiny bones called? What do these bones do?
malleus, incus, and stapes
convert sound vibrations from the air to fluid vibrations in the cochlea
What is the elastic partition that runs from the beginning to the end of the cochlea, separating it into upper and lower parts?
the basilar membrane
How do we hear - once fluid inside the cochlea ripples, a traveling wave forms along the _____ ____
basilar membrane
Sensory cells in the basilar membrane move up and down, and _______ on the top bump against the overlying structure and bend - what does this bend cause?
stereocilia - bending causes channels to open up, allowing chemicals to rush into the cells creating an electrical signal that the auditory nerve carries to the brain.
What determines the vibrations?
the shape of the cochlea
Sounds com in different frequencies related to _____
pitch
Where do you find high and low frequencies in the cochlear structure?
High = at base Low = aat apex
Sound intensity (aka?) is defined as what?
the sound per unit area
what is the SI unit of sound intensity?
watt per square meter (W/m^2)
Approx. how many decibels is a normal conversation?
60 dB
How do we commonly express sound intensity?
using the decibel scale
The decibel scale can help to determine how loud something is relative to the ___ ___ ___
Threshold of Hearing (TOH)
Sounds with equal intensities may be perceived as unequal loudnesses due to what?
frequency differences!
____ is used to indicate an individuals perception of loudness - what is the dB/Hz units for this?
Phon
1 Phon = 1 dB at 1000 Hz
____ and ____ are used to indicate an individuals perception of loudness - which tells us HOW MUCH louder one sound is than another?
Phons and Sones
Sones
Going up every ___ phons is doubling the sound when looking at the sone scale
10
We are most sensitive to sounds between __ - __ Hz
1000-4000 Hz
During temporary hearing loss, we lose our ability to hear between 1000-4000 Hz which is considered what zone?
talking zone
Hearing threshold elevation at high frequencies = ____
presbycusis
As we get older, where do we see impairment?
In the higher ranges
Lose Sensitivity (neural/cochlear) - threshold shift - audible spectrum decreases to __-__ Hz
50-8000
What is NIHL?
noise-induced hearing loss
T/F: NIHL can be immediate or it can take a long time to be noticeable, it can be temporary or permanent and it can affect one or both ears
TRUE :)
Good job Ash and Em, keep up the hard work.
Approx. __% of Americans between 20-69 have hearing loss caused by exposure to noise where?
15% (26 million)
Work or Leisure Activities
__% of teens (12-19 yrs.) have reported some hearing loss caused by loud noise.
16%
What causes NIHL?
one-time exposure to “impulse” sound or continuous exposure to loud sounds
Long or repeated exposure to sounds at or above __ dB can cause hearing loss
85
Most NIHL is caused by what kind of damage?
damage and eventual death of hair cells - human hair cells dont grow back
It is recommended a 3 dBA exchange rate - what does this mean?
every increase by 3 dB doubles the amount of noise and halves the recommended exposure time
What can you use sound level meters to create?
a sound contour map
highest prevalence for NIHL from construction trades?
welder
What job has been isolated as one of the highest problematic areas for NIHL in Canada?
carpentry
The average __ year old carpenter has the ears of a __ year old person who has not been exposed to noise
25
50
Effects and signs of NIHL?
- slowly start to lose hearing due to gradual damage
- sounds become distorted or muffled, difficult to understand speech
- might be severe enough to need hearing aids
____ is a ringing, buzzing or roaring in the head when no external noise is present - this can be caused by NIHL
tinnitus
Where is the damage in individuals with tinnitus?
damage or improper transmission through sensing organs or pathway to brain
“sometimes exposure to impulse or continuous loud noise causes a temporary hearing loss that disappears 16-48 hours later”
temporary threshold shift (TTS) aka auditory fatigue
How does intense noise cause damage?
displaces the basilar membrane to a greater extent, therefore the vibration is large = hair cell bending is more intense with considerable force
How do hair cells recover?
will shift and recover with time away from noise
How are Temporary threshold shifts (TTS) measured and when are they usually experienced?
2 minutes following exposure to avoid recovery
usually experienced at frequencies higher than the exposure frequency, usually 4000 Hz
What can chronic noise exposure cause?
Raised levels of cortisol and other stress hormones
A weak correlation between long-term noise exposure above 67-70 dB and ______
hypertension
Noise levels of 50 dB at night may increase the risk of?
myocardial infarction
Roadway noise levels are sufficient to constrict arterial blood flow, leading to elevated?
BP
What else has noise been associated with?
headaches, ulcers, fatigue and vertigo
The vestibular system encodes ____ and ___ acceleration of the head
linear and rotary
How does the vestibular system signal the brain to move the head?
with respect to a constant gravitational acceleration of the earth
What three things does the vestibular system do?
- detects acceleration forces
- maintains upright posture/balance
- controls eye position relative to head
Semicircular canals code for ____ acceleration
angular acceleration in 3 axes
a ___ embedded in a jelly-like material (cupola) us supported by hair cells that bend and fire in response to head rotation
crista
Vestibular sacs (utricle and saccule) code for ____ acceleration
linear
How do the vestibular sacs code acceleration?
Linear acceleration is coded for when hair cells in jelly-like substance lag behind when head moves
____ are involuntary movements of the eyes - these are mixtures of slow and fast movements and they can occur normally when tracking a visual pattern
nystagmus
Nystagmus can also be abnormal and accompanied with _____
vertigo
What are the two types of Nystagmus?
Spontaneous (presented spontaneously) and Positional (presented with a change in body position, specifically the neck)
