Lab - Special Senses Practical: Taste, Smell & Hearing Flashcards
How can we test hearing?
Using an audiometer
Frequency - Start with 1000Hz
Intensity - Shouldn’t have to go higher than 50-60 decibels for this
When intensity is selected press Tone and subject should be able to hear sound
Reduce intensity until subject no longer hears sound
Select a different frequency and repeat process until you have covered the frequencies (125, 200, 500, 1000, 2000, 4000, 8000) on the audiogram
Repeat for other ear by flicking the ear switch to either right or left
How do we record Audiogram results?
On audiorram put a cross on 1000 Hz frequency line at the threshold intensity level identified for your subject
Select a different frequency and repeat process until you have covered the frequencies (125, 200, 500, 1000, 2000, 4000, 8000) on the audiogram
Use a circle to record thresholds for right ear on audiogram
Sketch what you would consider a “perfect” response to be?
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Between -10 - 20 DB
What would the response of a 50 year old man who has worked in a loud factors for 30 years look like ?
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40 - 70 DB
Frequency drops at background noise as hair cells at these positions in the cochlea would be damaged by the dB level
How do you detect someone fraudulently pretending to be deaf?
Hi Tech - fMRI
Lo Tech - reflex response to sudden frightening noise
If someone is deaf on Audiogram do an OAE test and if OAE is normal faking deafness
OAE or otoacoustic emission testing is the recording of sounds that the ear produces itself.
What are the causes of air conduction deafness?
Causes of air conduction deafness;
- External ear blockage (objects or infection)
- Middle ear infection
- Ossicles ossification
- Tympanic membrane rupture
- Congenital defects blocking the air pathway
What are the causes of sensorineural deafness?
Causes of sensorineural deafness;
- Damaged/malfunctioning hair cells
- Auditory nerve damage
- Primary Auditory cortex damage
- Congenital conditions of auditory neurones
In the dichotic listening test (info coming in both ears) what might be the reason that someone has a dominant ear?
Dominant left hemisphere of cerebral cortex leading to right ear advantage. Right sided dominance leading to left ear advantage is ‘atypical’
Language functions such as grammar, vocabulary and literal meaning are typically lateralized to the left hemisphere, especially in right-handed individuals. In contrast it is more bilateral, or even right lateralized in left-handers. Broca’s area and Wernicke’s area are associated with the production of speech and speech comprehension are both located in the left cerebral hemisphere for most right-handers but only about 70% of left-handers.
What is the cocktail party effect?
The cocktail-party effect refers to the ability to focus one’s attention a particular stimulus while filtering out a range of other stimuli (i.e., noise).
Might not be able to hear it if have Tinnitus
How does 3D sound work?
To put it simply, 3D sound takes normal sound effects produced by speakers and processes them in such a way that the sounds are virtually placed anywhere in the three-dimensional space around the listener.
In reality, the perceived difference with 3D sound comes from tricking the listener’s brain into thinking sounds are coming from different directions in 3D space around them.
If you had hearing loss on one side what aspects of life might you struggle against and how might you mitigate against them ?
- Reduced directional pinpointing
- Reduced speech intelligibility
Your brain will have trouble filtering out extra noises and selectively listening to the sounds that are important. This might make it difficult for you to focus on something one person is saying to you
Might struggle crossing road, telling what way traffic is coming, may tilt head to determine where sound is coming from.
What happens in the McGurk effect?
The same sound is playing but when you look at different mouth movements you hear different words
This illustrates how important vision is in interpreting sounds
Important patient communication with those with hearing impairments !
Why might tasting with a nose clip on alter the taste of something?
That’s because the upper part of your nose isn’t clear to receive the chemicals that trigger the olfactory receptors (that inform the brain and create the sensation of flavor). Nose plays important role !
What can lemon juice cause and what pathway does this stimulate?
Lemon juice stimulates salivation;
The facial (CN VII), glossopharyngeal (CN IX) nerves to terminate in the nucleus of the solitary tract (NST) in the brainstem - the superior (CN VII) and inferior (CN IX) salivatory
nuclei.
Inferior innervates parotid salivary gland and superior innervates submandibular and sublingual glands.
What can raw onions cause and what pathway does this stimulate?
Lacrimation !
Superior salvatory nucleus through greater petrosal nerve (branch of CN VII) to pterygopalatine ganglion through lacrimal nerve to lacrimal gland.
