how much is a 10 fold increase in sound energy?
1 bel
What is the measurement of a decibel_
1/10 log (I* measure sound / I * standard sound)
What is energy proportional to?
energy is proportional to the square of pressure
what is the decibel of a whisper?\
20 dB
What is the decibel of normal conversation?
60dB
What is the decibel of a symphony?
100dB
what is the decibel of threshold of discomfort?
130dB
What is the decibel for threshold of pain
160dB
In a young adult what are the frequencies of audible sound?
20-20k Hz (decreases with age)
IN what frequency is the greatest acuity for audible sound?
1000-4000 Hz
In what range does impedance matching work?
300-3000 HZ perfect for sound (50-75%)
How much smaller is the oval window compared to the Tympnic membrance?
17 times
What does the ossicular system do?
reduces amplitude by 1/4
increases pressure against oval window by 22 times (gives increased force of 1.3 times)
By how many decibels can the ossicular system reduce loudness if not working?
15-20 dB
When the stepedius muscles pulls the stapes outward it does what to sound?
decreases sound
When the Tensor Tympani pulls the malleous inward what does it do to sound?
increases loudness
When a CNS reflex causes the contraction of sapedius and tensor tympani muscles, it is called?
creation of rigid ossicular sytem
what does a rigid ossicular sytem do?
reduces ossicular conductions
What are the chambers of the cochlea?
Scali vestibuli, Scali media, Scali tympni
What seperates the Scali Vestibuli and Scali media?
Reissner’s membrane
What seperates the Scali media from the Scali tympani?
basilar membrane
what two chambers of cochlea are filled with perilymph?
Scali vestibuli and Scali Tympani
What are the top of hair cells bathed by in the Scali media?
endolymph
What cation is the Scali media enriched with?
Enriched with K+ that is secreted by stria vacularis
What secretes the K+ that enriches the Scali media?
stria vacularis
what chamber is associated with the round window?
Scali tympani
What chamber is associated with the oval window?
Scali vestibuli
What is the scala media filled with?
endolymph (K+)
What is the cala tympani filled with?
perilymph (CSF)
what baths the bottoms of hair cells?
perilymph
what frequencies do the hair cells near the oval window respond to?
> 4500Hz
what are the characteristics of hair cells near oval window (base)?
short and thick
What are the characteristics of the hair cells near helicotrema?
long and slender.
to what frequencies do the hair cells near helicotrema respond to best?
best to lower frequencies (<200Hz)
What does the cochlea behave like?
Fourier analyser (kind of auditory prism)
What is Fourier analysis?
any complex wave ca be broken down into its component sine waves with differing phases frequencies, and amplitudes
What is the organ of corti?
cochlea
where is the primary auditory cortex located?
superior gyrus of temporal lobe
where are high frequency sounds located in the cortex?
posterior
where are low frequency sounds located in the cortex?
anterior
what pathway involves direct stimulation of cochlea through the vibration of the skull as the cochlea is imbedded in the petrous portion of the temporal bone?
bone conduction pathway
what pathway involves the external ear canal, middle ear, and inner ear?
air conduction pathway
IF a weber test sounds louder in bad ear, what is suspected?
air conduction loss in bad ear (external canal or ossicles involved)