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Audiology Resource Notebook This presentation is intended as a resource for professionals in Deaf Education, Audiology, and Speech Pathology. Presentation on theme: "Audiology Resource Notebook This presentation is intended as a resource for professionals in Deaf Education, Audiology, and Speech Pathology. Speech Audiometry Continued Word Recognition Score (WRS) The stimuli are a list of 25-50 phonetically balanced one syllable word. Barotrauma Discomfort in the ear caused by pressure differences between the outer and middle ear. Otosclerosis Otosclerosis is the growth of spongy bone-like tissue around the footplate of the stapes and blocks the oval window.
Otosclerosis Continued Maximum conductive loss is between 50-60dB, with a mixed loss it will increase to 60-70dB.
Audiogram: Otosclerosis One of the characteristic features of an audiogram that indicates otosclerosis is a smaller air bone gap at 2000Hz.
Audiogram: Presbycusis Audiograms that indicate presbycusis show a sharp drop off in the frequencies above 2000Hz. Malignant Otitis Externa Occurs in elderly diabetic patients, can occur in AIDS patients Characterized by persistent and severe earache, foul-smelling purulent otorrhea, and granulation tissue in the ear canal.
Otitis Media Continued Suppurative otitis media is characterized by fluid that contains puss. Otitis Media Continued Adhesive otitis media, or glue ear, is characterized by a thick, sticky effusion that causes the eardrum to become severely retracted.
A conductive hearing loss is caused by any condition or disease that impedes the conveyance of sound in its mechanical form through the middle ear cavity to the inner ear. The reason for sensorineural hearing loss sometimes cannot be determined, it does not typically respond favorably to medical treatment, and it is typically described as an irreversible, permanent condition.
A mixed hearing loss can be thought of as a sensorineural hearing loss with a conductive component overlaying all or part of the audiometric range tested. The conductive component may be amenable to medical treatment and reversal of the associated hearing loss, but the sensorineural component will most likely be permanent. Loss of hearing that gradually occurs because of changes in the inner or middle ear in individuals as they grow older. Presbycusis is the loss of hearing that gradually occurs in most individuals as they grow older.
Presbycusis may be caused by changes in the blood supply to the ear because of heart disease, high blood pressure, vascular (pertaining to blood vessels) conditions caused by diabetes, or other circulatory problems. Consultation with specially trained professionals who work as a team is important for evaluation of a hearing loss and selection of appropriate management. If you have a hearing loss caused by presbycusis or know someone who does, share these tips with family members, friends, and colleagues. The outer ear collects sound waves and works like a funnel to send them through a narrow tube (ear canal) that leads inside the ear.
The inner ear is filled with a thin fluid that transmits pressure changes throughout the cochlea.
NIDCD maintains a directory of organizations that can answer questions and provide printed or electronic information on presbycusis.
20.Murata K, Weihe P, Renzoni A, Debes F, Vasconcelos R, Zino F, Delayed evoked potentials in children exposed to methylmercury from seafood. This article focuses on hearing loss in infants. Causes About 2 - 3 infants out of every 1,000 live births will have some degree of hearing loss at birth. It includes information about the basic audiometric test battery, common causes of hearing loss, and example audiograms. Can be caused by over- productive cerumen glands, but is most often caused when attempts to clean the ear pushes wax deeper into the canal Causes conductive hearing loss. Causes conductive hearing loss, the larger the perforation the greater the loss Pain is usually not present.
It affects 30-35% of adults between 65 and 75 and increases to 40-50% of those over 75 Loss is sensorineural and in the high frequencies Tinnitus may occur There is a central auditory component that will result in lower WRS than expected Client reports that the speech of others sounds slurred or mumbled Conversations are harder to hear when there is background noise. A conductive hearing loss can be the result of a blockage in the external ear canal or can be caused by any disorder that unfavorably effects the middle ear’s ability to transmit the mechanical energy to the stapes footplate. Generally, the cause of conductive hearing loss can be identified and treated resulting in a complete or partial improvement in hearing.
The sensory component may be from damage to the organ of Corti, an inability of the hair cells to stimulate the nerves of hearing or a metabolic problem in the fluids of the inner ear. Like conductive hearing loss, sensorineural hearing loss reduces the intensity of sound, but it might also introduce an element of distortion into what is heard resulting in sounds being unclear even when they are loud enough.
So, in addition to some irreversible hearing loss caused by an inner ear or auditory nerve disorder, there is also a dysfunction of the middle ear mechanism that makes the hearing worse than the sensorineural loss alone. Hearing aids can be beneficial for individuals with a mixed hearing loss, but caution must be exercised by the hearing care professional if the conductive component is due to an active ear infection. Sounds waves may travel through the ear but this nerve pathway is unable to send electrical impulses to the brain. For example, it may be difficult for someone to hear the nearby chirping of a bird or the ringing of a telephone.
Most commonly it arises from changes in the inner ear of a person as he or she ages, but presbycusis can also result from changes in the middle ear or from complex changes along the nerve pathways leading to the brain. Such abnormalities may include reduced function of the tympanic membrane (the eardrum) or reduced function of the three tiny bones in the middle ear that carry sound waves from the tympanic membraine to the inner ear.
Awareness of potential sources of damaging noises, such as firearms, snowmobiles, lawn mowers, leaf blowers, woodworking machinery and loud appliances is important. An otolaryngologist (ear, nose and throat specialist) should evaluate the individual with a hearing problem to make the diagnosis and exclude related systemic disorders that may contribute to the problem. This allows a person with a hearing impairment to observe facial expressions, gestures, and lip and body movements that provide communication clues.
The bones pass the vibrations of sound waves to a small organ in the hearing part of the inner ear called the cochlea, which is a coiled structure like a snail shell.
Inside the cochlea are tiny hair cells that pick up sound vibrations from the fluid and cause nerve impulses in the auditory nerve.
The specific gravity may be considered as a measure of density of a given amount of solid substance, when it is compared to an equal amount of water. Interpreting the literature on lead and child development: the neglected role of the "experimental system". Distortion product oto-acoustic emissions in Andean children and adults with chronic lead intoxication. Effects of developmental exposure to methyl mercury on spatial and temporal visual function in monkeys.


Delayed brainstem auditory evoked potential latencies in 14-year-old children exposed to methylmercury. Roth,Richard Salvi Neurotoxicity Research. Each topic has its own table of contents, and, where possible, each section of information has an accompanying graphic.
In most cases there is a bony plate the separates the external ear from the contents of the middle ear.
Symptoms include pain, slight conductive hearing loss, and ear fullness If severe or prolonged, can cause moderate to severe hearing loss, feeling of pressure in the ears, nosebleed and middle ear pain. Can also cause sensorineural loss in the high frequencies, this type is known as cochlear otosclerosis. Following the completion of medical treatment for causes of the conductive hearing loss, hearing aids are effective in correcting the remaining hearing loss. The neural or retrocochlear component can be the result of severe damage to the organ of Corti that causes the nerves of hearing to degenerate or it can be an inability of the hearing nerves themselves to convey neuro chemical information through the central auditory pathways.
Once any medically treatable conditions have been ruled out, individuals with a sensorineural hearing loss can be fit with hearing aids to give them access to speech and other important sounds. However, the same person may be able to hear clearly the low-pitched sound of a truck rumbling down the street. Ear plugs or special fluid-filled ear muffs can give protection and should be worn to help avoid the possibility of damage to hearing. Assistive listening devices can provide further improvement in hearing ability in certain situations. An audiologist is a professional who measures the hearing and identifies the type of hearing loss.
The information contained within the presentation is meant to be a quick look-up guide to the most essential information with regards to these topics. Because the process of loss is gradual, people who have presbycusis may not realize that their hearing is diminishing. The cumulative effects of repeated exposure to daily traffic sounds or construction work, noisy offices, equipment that produces noise, and loud music can cause sensorineural hearing loss.
Excessively loud everyday noises, both at home and at work, can pose a risk to a person’s hearing. The audiologist conducts a complete hearing evaluation and determines if a hearing aid may be useful. Profound hearing loss is what most people call deafness. Some cases of hearing loss are progressive (they get worse over time).
Sensorineural hearing loss is most often due to a loss of hair cells (sensory receptors in the inner ear).
Avoiding loud noises and reducing the amount of time one is exposed to everyday noises may be helpful.
Another example is FM systems that make sounds clearer, with or without a hearing aid, by delivering sound waves like a radio. Heavy metals may enter the human body through food, water, air, or absorption through the skin, when they come in contact with humans in residential and occupational settings as well as from the general environment. This can occur as a result of hereditary factors as well as aging, various health conditions, and side effects of some medicines (aspirin and certain antibiotics).
Training in speechreading (using visual cues to determine what is being spoken) can help those with presbycusis to understand better what is being said in conversations or presentations.
Then the audiologist conducts tests to find an appropriate aid, selecting one that maximizes a person’s hearing and understanding of speech. Most older adults with hearing loss can benefit from using a hearing aid, although the degree of benefit may vary according to the type and amount of hearing loss.
Other uses include paint pigments, PVC plastics, x-ray shielding, crystal glass manufacture, pencils, glazing ceramics, canned foods with lead-solder joints, ethnic foods, herbal remedies, dietary supplements, lead emissions from fossil fuels, metal smelting, and pesticides. In this case, a repeated syllable is used and the client is asked to indicate when they can perceive the sound. Box 1- [Additional file 1] lists the health effects of lead.According to the World Health Organization's (WHO) World Health Report, following control measures, lead levels have been steadily declining in industrialized countries, but yet, at least 5% of the children still have elevated blood lead levels, with even higher rates in children of poorer households.
Causes of mixed hearing loss can include any combination of the above SNHL and CHL causes. Central hearing loss results from damage to the auditory nerve itself, or the brain pathways that lead to the nerve.
In many developing countries, where leaded gasoline is still used, lead can present a threat to more than half the population of children. If they do not reach these milestones, hearing loss since infancy may be the cause. Some children may not be diagnosed until they are in school.
Inattention and falling behind in class work may be the result of an undiagnosed hearing loss problem. Exams and Tests Hearing loss results in a baby's inability to hear sounds below a certain level. A baby with normal hearing will hear sounds below that level. The health care provider will examine your child. The exam may show problems such as bone problems or signs of genetic changes that may cause hearing loss. The doctor will use an instrument called an otoscope to see inside the baby's ears. In their study, a low standard of living correlated with a 32% increase in blood lead levels.
This test uses patches, called electrodes, to determine how the auditory nerve reacts to sound. Otoacoustic emissions (OAE) test. The most toxic exposures occur at chronic low levels and can result in reduction in intelligence quotient (IQ), increased blood pressure, and a range of behavioral and developmental effects. Furthermore, lead is now understood to be toxic, especially to children, at levels previously thought to be safe. If there is no echo, it is a sign of hearing loss. Older babies and young children can be taught to respond to sounds through play.
In more severe cases of poisoning, adverse health effects include gastrointestinal symptoms, anemia, neurological damage, and renal impairment.
These tests, known as visual response audiometry and play audiometry, can better determine the child's range of hearing. Treatment Over 30 states in the United States now have mandatory hearing screenings of newborns. Other adverse effects, such as reduction in IQ levels, behavioral disorders, or renal dysfunction, can be discerned only through special examinations. Early treatment of hearing loss can allow many infants to develop normal language skills without delay.
In infants born with hearing loss, treatments should start as early as possible, preferably by 6 months of age. Treatment depends on the baby's overall health and cause of hearing loss. Advances in hearing aid technology and speech therapy allow many children to develop normal language skills at the same age as their peers with normal hearing. Vaccinations against several types of bacteria that cause meningitis are available, and may reduce the risk of the disease in a child with a cochlear implant.


Some studies have shown a relationship between blood lead levels and hearing loss, [11],[12],[13] but Counter et al.
It has also been suggested [12],[14] that lead exposure results in hearing loss, which in turn may be responsible for developmental learning disabilities. Osman et al , [13] reported delayed wave I of the auditory brainstem response in children exposed to lead. It is clear that there are substantial differences in the current literature on the effect of lead exposure on the auditory sensitivity indicated by pure tone audiometry. Lead and noise: Effect on hearing There are very few studies exploring the effects of combined lead and noise exposure. Multivariate analysis showed a significant correlation between high long-term lead exposure (duration of employment and ambient lead concentration), with the hearing threshold at 4 kHz, but no correlation was observed with short-term exposure.
The raised thresholds between 2 and 8 kHz may be due to the combined exposure to lead and noise. Absolute brainstem response latencies were prolonged, but the inter-wave intervals were normal, indicating a conductive element to the hearing loss.
Counter and Buchanan [8] suggested that environmental exposure must be considered an important factor in adults who were occupationally exposed to lead.
Lead and noise: Human growth Lead exposure has an impact on Human growth and development, [17] and noise stress is also considered to be implicated in the reduced prenatal growth. The health effects also cover many neurological and psychological symptoms as shown in Box 3 - [Additional file 3]. In 1953, a severe neurological disorder was recognized among persons living in the vicinity of Minimata, Japan, where mercury-containing effluent flowing from a chemical plant into the local bay contaminated shell fish.
After the incident, deterioration in hearing and deafness were reported among other neurological symptoms, in the local people. Findings consistent with Minimata disease have been reported in other instances of accidental mercury poisoning in Japan and Iraq. Early stages of intoxication may result in cochlear lesions, whereas, hearing loss in the late stages of intoxication may result from neurological damage.Methyl mercury is considered more toxic than mercuric chloride.
Hearing loss due to Methyl mercury has been reported, [18] while wave III of the auditory brainstem response has been shown to be delayed and used as a biomarker for prenatal MeHg toxicity from contaminated seafood.
Dimethyl mercury, Methyl mercury, and Mercuric Sulfide have all been shown to affect auditory brainstem potentials.
It can be found in soils because insecticides, fungicides, sludge, and commercial fertilizers that use cadmium are used in agriculture.
Lesser-known sources of exposure are dental alloys, electroplating, motor oil, and exhaust. Inhalation accounts for 15-50% of absorption,and 2-7% of ingested cadmium is absorbed in the gastrointestinal system.The health effects range from occupational lung cancer, kidney damage from tubular dysfunction to chronic renal failure, skeletal damage, and hearing dysfunction.
Cadmium: Hearing Dose-dependent effect on hearing has been shown in rats by Agirdir and Ozcagalar, in 2002. Increased blood and renal cortical cadmium levels were associated with high cadmium accumulation in ear ossicles and labyrinth in rats exposed to cadmium. The changes in auditory brainstem responses and otoacoustic emissions in two-month old male rats exposed to drinking water containing 5 and 15 ppm, for 30 days, showed that cadmium-induced nephrotoxicity was associated with signs of defective hearing at a concentration of 15 ppm, but at 5 ppm it caused hearing loss without affecting the kidney function.
Nonsignificant changes in wave III and V latencies were accepted as evidence of an unaltered function of the other parts of the auditory system. These results suggest that hair cells are more sensitive to cadmium than kidney tubule cells and that the cochlear component of hearing is more vulnerable to cadmium toxicity than other parts of the auditory system. Preventive effect of a zinc-enriched diet on cadmium-induced hearing loss in rats was investigated by Agirdir and Ozcaglar.
A third group received 15 ppm CdCl 2 and food enriched with 200 ppm zinc as ZnSO 4 for 30 days.
Hearing function was measured by using the auditory brainstem response and distortion product otoacoustic emission. A zinc-enriched diet obviously reduced cadmium accumulation in the kidney and prevented nephrotoxicity. Cadmium-induced ototoxicity seemed to be partially zinc preventable and addition of zinc to the diet without altering the cadmium content in the ear ossicles might help to prevent cadmium- induced hearing loss. In the groups exposed to continuous noise for six hours, the total percentage of malformed fetuses was significantly higher than that in the control group.
Although combined treatment with cadmium and noise resulted in an increase in the total percentage of malformed fetuses compared to the same dose of cadmium alone, the interactions between cadmium and noise showed no synergistic effect on the teratogenicity. The magnitude of teratogenicity due to noise was much weaker than that of cadmium, and was therefore easily masked by that of cadmium in the statistical tests of the significance of differences.
Arsine gas is a common by-product produced by the manufacturing of pesticides that contains arsenic. Arsenic may also be found in water supplies worldwide, leading to exposure in shellfish, cod, and haddock. Arsenic: Hearing Considerable variability among individual arsenic values in the hair makes group examination a necessity.
Hair, urine, and blood samples taken from groups of 10-year-old boys, each having 20 to 25 individuals, residing in a region polluted by arsenic and hearing changes were analyzed in a group of 56 10-year old children residing near a power plant burning local coal of high arsenic content. In the case of air conduction, significant hearing losses were found at frequencies of 125, 250, and 8000 Hz.
The high statistical significance of hearing impairments found, pointed to a very low probability of there being only an "accidental" finding.
The possibility of toxic damage to the ear could yet not be excluded according to Bencko and Symon. It is also not clear whether lead and noise combined exacerbate hearing loss, but they do affect human fetal growth. Mercury affects hearing, with central conduction time delay (ABR I-V, III-V), but cochlear function may be unaffected. Cadmium causes dose-dependent loss of hearing in rats, and a delay in only Wave I of the auditory brainstem response implies cochlear dysfunction.
Cadmium and noise show a synergistic effect at 4 kHz and 6 kHz, and on human fetal malformations.




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