What are hearing tests?

Indications and Procedures

Hearing tests are done to establish the presence, type, and severity of hearing impairment in children and adults. Such tests are conducted by an audiologist, although screening tests can also be done by a technician under the supervision of an audiologist. The severity of hearing loss is classified as mild, moderate, moderately severe, severe, and profound. It is also classified according to the anatomic region affected: conductive, sensorineural, or mixed hearing loss.

The selection of tests to evaluate hearing will depend on the patient’s age and ability to follow directions and the ability of the audiologist to elicit responses from the patient. When a patient cannot follow instructions such as lifting a hand or pressing a button, a test that does not require the patient’s cooperation is used. Two tests that do not require the patient’s cooperation are the auditory brainstem potential (ABR) test and the evoked otoacoustic emissions (EOAE) test. Both tests require only that the patient be quiet. For this purpose, the patient may need sedation if normal sleep cannot be induced.

The ABR test requires the placement of four electrodes on the patient’s head: in both mastoid regions and in the mid forehead and upper center of the head. A stimulus is sent through a small microphone placed in the patient’s external ear canal or via headphones. The instrument records the average of the electrical discharges generated by the auditory nerve in response to sound stimuli and produces a tracing of waves that correspond to the different electrical potentials generated in response to the stimuli. Analysis of the waves can determine the presence of hearing loss and measure its severity. The ABR test may be used for screening, to determine whether the subject can hear, or for the clinical evaluation of hearing loss. It can be done at any age. An automated method of ABR testing is available for screening newborn infants for hearing loss; it automatically determines if the patient has passed or failed. The clinical ABR test requires specially trained personnel and takes from forty-five to fifty minutes to perform. The automated method can be applied by a technician.

The EOAE test involves recording the sound produced by hair
cells within the cochlea by way of a microphone placed in the outer ear canal. Normally, when sound enters the cochlea, the hair cells produce a sound that bounces backward and can be recorded. This sound correlates with the sound sent to the auditory nerve. If there is damage to the hair cells in the cochlea, then no sound is elicited. The EOAE test can be performed without sedation if the patient cooperates by staying quiet. It can be done by a technician and takes approximately ten minutes or less. The EOAE test is used for universal screening of newborn infants. It can be done at all ages to help determine the integrity of the cochlea and thus whether an observed hearing defect is within the cochlea.

Behavioral techniques are the most practical, cost-effective, and time-efficient methods for the accurate assessment of hearing. They give more complete information on the child’s hearing as well as functional information about how the child uses his or her hearing. The simplest test is behavioral observation audiometry, in which the audiologist records the behavioral response to an applied sound stimuli of a known frequency. This test can be done with infants up to six months of age, toddlers, and uncooperative patients, such as children or adults with developmental delays. Visual reinforcement audiometry (VRA) is done with infants and toddlers from six months to twenty-four months of age. It is also used with uncooperative patients. In this test, the patient is submitted to sounds of different intensity and trained to respond to the sound stimuli by means of an attractive stimulus. Every time that the sound appears, the stimulus illuminates. When the patient hears the sound, he or she will look for the reinforcement. Play audiometry is a test that can be used in children over two
years of age. The child is taught to move a block or place a puzzle piece every time he or she hears a sound.

In 2002, Ruth Litovsky, an University of Wisconsin–Madison communicative disorders professor, introduced a binaural hearing test to evaluate how people respond to sounds in a noisy environment resembling public areas and schools. Using computers showing images related to words being broadcasted on loudspeaker, her test assesses which sounds people ignore and which sounds secure their attention.

In 2003, the Ear, Nose, and Throat Journal provided information describing the Otogram from Tympany, a Sonic Innovation subsidiary. This device enables patients to test their hearing at sites using automated technology. During the twenty-minute testing period, patients undergo an audiogram that thoroughly evaluates their acoustic capabilities with tympanometry and other standard diagnostic tests, responding to the tests via touchscreens with results recorded by computer.

In 2005, Bio-Logic Systems Corporation and House Ear Institute researchers introduced the hearing in noise test (HINT), which assesses how hearing functions in police and emergency personnel whose hearing is vital to their work. The test involves subjects repeating sentences while exposed to a variation of noise and quiet. The source azimuth identification in noise test (SAINT) evaluates subjects’ ability to detect where sounds are located.

Perspective and Prospects

Early detection of hearing loss has become a priority among intervention services because it has devastating effects on language development and consequently on social adaptation. It has been found that the mean age at which deafness is diagnosed is around three, which is after speech development should have occurred. Thus, children with hearing loss are placed at a disadvantage with their peers.

In 1993, the National Institutes of Health (NIH) developed a consensus statement by which all newborn infants in the United States were to be screened for hearing loss. The aim was that by the year 2000, all newborns would have been screened before being discharged from the hospital. By 1999, many US states had passed legislation requiring hearing screening of newborns, but a study described in the July, 1999, issue of American Journal of Otology recommended screening only babies with a risk for impaired hearing, stating that pediatricians and child care providers would detect deafness in infants and toddlers.

The October, 2001, the Journal of the American Medical Association
evaluated nineteen studies, emphasizing that screening newborns was not superior to tests by pediatricians when infants were several months old and stressing that determining the value of newborn screening required additional study. In October, 2005, the Archives of Pediatrics & Adolescent Medicine estimated that more than half of children whose hearing test results revealed that they needed additional tests never underwent such testing.

The role of otitis media (middle-ear infections
) in producing hearing impairment is an area of great concern and controversy. Special attention to the hearing evaluation of children with recurrent and chronic otitis media is indicated.

Bibliography

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Dobie, Robert A. and Susan B. Van Hemel, eds. Hearing Loss: Determining Eligibility for Social Security Benefits. Washington, D.C.: National Academies Press, 2005

de la Rocha, Kelly. "Audiometry." Health Library, November 11, 2012.

Elder, Nina. “Now Hear This—Check Your Baby’s Hearing.” Better Homes and Gardens 78, no. 5 (May, 2000): 264.

Glaser, Gabrielle. “Pediatricians Urge Hearing Tests at Birth.” The New York Times, April 6, 1999, p. 7.

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Hearing Exchange. http://www.hearingexchange.com.

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Roush, Jackson, ed. Screening for Hearing Loss and Otitis Media in Children. San Diego, Calif.: Singular, 2001.

Sataloff, Robert T., and Joseph Sataloff. Hearing Loss. 4th ed. New York: Taylor & Francis, 2005.

What theme is illustrated by Désirée's acceptance of blame for the baby's skin color?

Kate Chopin leaves many ambiguities in her short story "Desiree's Baby." Whether Desiree does or does not accept that she is the reason her baby has African features is unclear. In fact, initially she protests vehemently when Armand says, "It means that the child is not white. It means that you are not white." She shows Armand her hand and declares that it is whiter than his. She writes to her mother urging her to "tell them it's not true." Madame Valmonde writes back, telling her to come back home to her with the baby. There is no indication that Desiree ever believes she herself is of mixed race. On the contrary, Chopin's word choice seems to reinforce that Desiree continues to believe in her whiteness. When she lays the letter before Armand, she stands there "silent, white, motionless." When she leaves the house with the baby, "Desiree had not changed the thin white garment" that she wore, and presumably had not changed her conviction about her racial heritage. 

The only indication that suggests Desiree accepts Armand's explanation of their child's looks is that Desiree leaves the plantation when Armand says he wants her to go. However, Desiree no doubt has enough pride to not stay with a husband who expressly wants her to leave. In addition, she realizes that if she is not of mixed race, that Armand must be, and that he will never tolerate such a fact to be made known. She will need to be sacrificed for his secret.

Whether Desiree accepts Armand's explanation or whether she merely acquiesces to it, the theme her actions support is the same. The theme Chopin presents is that in a patriarchal society, a woman is powerless even if she is in the right, and she is at the complete mercy of her husband's whims, beliefs, and desires. 

What major themes and comments on life are evident in the poem "Song of Myself"?

This long poem, a piece of Leaves of Grass, is a spontaneous self-portrait in prose form, celebrating Whitman’s individuality while acknowledging how all humanity is alike (like “leaves of grass”). 

“I harbor for good or bad, I permit to speak at every hazard,/
Nature without check with original energy.”

Whitman’s consistent and unequivocal comment on life is to live it, every day, every moment, to savor and enjoy and be ultra-conscious of your own facticity:

 “My respiration and inspiration, the beating of my heart, the
     passing of blood and air through my lungs,
The sniff of green leaves and dry leaves, and of the shore and
     dark-color'd sea-rocks, and of hay in the barn,”

A second, related theme is that the universe is infinite, that our immediate existence is but a fraction of all that is:

     “You shall possess the good of the earth and sun, (there are
     millions of suns left,)”

Whitman’s “song” is that there is no limit to our experience as living creatures, as spirits given the blessing of our existence.  While it is difficult for us as common men to see the grandeur, Whitman manages to point to it and invite our souls to celebrate the fact of being.

These themes are so large in concept, so vital to our understanding of Whitman's life-message, that paraphrasing or condensing them is "murdering to dissect,"  that is the "life" of the poem itself is diminished; reading the poem is all the "analysis" you need in order to understand his connection to the reader.

What process causes volcanoes to form along the mid-ocean ridge?

The mid-ocean ridge is a continuous underwater range of mountains which virtually encircle the globe. These mountains are formed along the boundaries of tectonic plates where new ocean floor is created when tectonic plates move apart.

Tectonic plates are moved apart by convection in the upper mantle. As the tectonic plates move apart, molten rock ascends, right through to the sea floor, producing huge volcanic eruptions of lava, called basalt. The enormous force of the lava eruption further aggravates the divergence of the tectonic plates.

Tectonic plates spread apart at varying rates. Plates with slow spreading rates of about 2 to 5 cm per year develop deep rift valleys along their crest but fast spreading ones with rates of about 6 to 16 cm per year develop a smooth volcanic summit with only a crack along their crests.

What are the differences between Banquo and Macbeth with relation to the witches' prophecies?

Macbeth is prophesied to be king, while Banquo will be the father of kings. At the beginning of the play, these two soldiers had been friends, fighting together in the battle. With the prophecy, however, things begin to change. Macbeth, believing wholeheartedly in the prophecy, immediately sees murder as the means by which he can get rid of Duncan, as well as Duncan’s sons, Malcolm and Donalbain. When he contemplates the witches’ prophecy of Banquo’s sons becoming kings, he puts two and two together: his own sons will not inherit the crown. Instead, it will go to the offspring of Banquo (a historical note: Banquo’s descendant was James I, the king of England when Shakespeare wrote the play). Therefore, Banquo must die (even though he is not prophesied to be king himself). His sons also must be killed.

Macbeth’s hubris (pride) easily twists his soul, seeing murder as a requirement to achieve his destiny. He had momentarily thought that he should do nothing, and that his fate would happen without his own effort. Then he decides that he cannot take that risk. Previously a loyal subject and friend, his relationship with Duncan as well as Banquo is twisted.

Banquo, understanding the prophecy as well, does not see it as “fate.” He believes it is the work of the devil, in order to get Macbeth and himself to commit evil. He rejects this, and begins to distance himself from Macbeth, at least emotionally.

The difference between the two men, therefore, is the nature of the souls. Macbeth is easily corrupted, while Banquo is strong in character. In the end, it is this difference that brings about the result of the prophecy. Macbeth does not live long enough to pass the crown onto his son, which the witches didn’t prophesy. Banquo, who chooses righteousness, does nothing to help the prophecy along; as a result, it comes true.

Why is the world we live in today interested in not only the quality of goods we buy but in how those goods and services are produced?

Have you ever seen references to the internet meme “first world problems?”  I believe that we care not only about the quality of the products we buy, but about how they are produced, because we are so rich that we have the ability to do so.

In the past, we were not nearly as rich as we are now.  Before WWII, the average American did not live the sort of affluent lifestyle that we now have.  Even in the boom years after the war, the typical American did not live as well (in material terms) as we do now.  Most people did not have two cars.  Houses were much smaller than they are now.  People did not go out to eat all the time or spend their money on fancy cups of coffee products.  It is only in the last few decades (no matter how much we complain about the weak economy or rising inequality) that the vast majority of Americans have come to have so much material wealth.

The psychologist Abraham Maslow said that human beings have to have their basic needs fulfilled before they can care about other things.  Speaking of individual people, he said that a person has to have food and shelter, for example, before they can worry about things like morality. I think that the same sort of thing applies to our society as a whole.  When we were worried about having enough material goods, we were not able to care about other things.  Now, we have enough material goods.  We have the luxury of worrying about how they are made.  We have the luxury of wondering if they were made in ways that harmed the environment or exploited workers in other countries.  When we were poorer, we did not care about these things because we just wanted to fulfill our more basic needs.  Now that our basic needs are amply provided for (and have been for at least a couple of decades), we have been able to move on to thinking about things like the morality of how our goods and services are made.

What is the proper chemical formula and model for water?

The chemical formula of water is H2O. One molecule of water contains 2 atoms of hydrogen and one atom of oxygen. It is a covalent molecule and has a definite geometry. The central atom is oxygen.   The electronic configuration of Oxygen in the ground state is

1s2 2s2 2p4. (atomic number of oxygen is 8).

The 2s orbital containing 2 electrons and the three 2p orbitals containing a total of 4 electrons of oxygen undergo  sp3 hybridization. Hybridization is the process of mixing up of orbitals of slightly different energies of an atom to give same number of equivalent orbitals. The hybrid orbitals will have the same energy and shape. In this case 4  sp3 hybrid orbitals are formed. According to VSEPR theory these hybrid orbitals will get themselves arranged around the central atom in such a way that repulsion between them is minimum. Here the orbitals are arranged tetrahedrally around the central oxygen atom. The angle between the orbitals in the tetrahedral arrangement is 109028’. As an orbital can accommodate only two electrons, the 6 electrons are distributed among the 4 hybrid orbitals such that two orbitals contain two electrons each (paired electrons) and the remaining two contain one electron each (unpaired electron). Only half filled orbitals containing one electron (unpaired electron) can form covalent bond. Hence the two half-filled sp3 hybrid orbitals of oxygen form covalent bonds with two hydrogen atoms.

The electronic c configuration of Hydrogen atom is   1s1. (atomic number of hydrogen is 1).

The 1s orbital of hydrogen is half-filled (contains only 1 electron).

According to Valence Bond theory, a covalent bond is formed by the overlap of two half-filled orbitals containing electrons of opposite spin of two atoms. Thus in water, the two half-filled sp3 hybrid orbitals of oxygen  overlap with the half-filled 1s orbitals of 2 hydrogen atoms to form covalent bonds. The overlap of the orbitals takes place along the inter-nuclear axis resulting in the formation of sigma type covalent bonds. (if the overlap takes place sideways, a pi bond is formed). In water the two O-H bonds are of sigma type.

In water, the central oxygen atom has two bond pair electrons (from two covalent bonds) and two lone-pair of electrons (from two completely filled orbitals not involved in bond formation) .According to VSEPR theory the repulsion between the orbitals are in the order

Lone pair-lone pair> lone pair- bond pair > bond pair-bond pair.

As there are 2 lone pair electrons, the bond pairs get repelled and the H-O-H bond angle decreases from the normal tetrahedral angle of 109028’ to 104.50. Water is thus a bent molecule. It is a V-shaped molecule.

The atomic radius of Oxygen is greater than that of hydrogen. Hence oxygen is bigger in size than hydrogen.

Oxygen is more electronegative than hydrogen.Electronegativity is a measure of the tendency of an atom to attract the shared pair of electron s (bonded pair of electrons) of a covalent bond towards itself in a molecule. Since oxygen is more electronegative than hydrogen the shared pair of electrons in the O-H bond is displaced towards oxygen atom. As a result a partial negative charge develops at the oxygen atom and a partial positive charge at each hydrogen atom. The O-H bond is thus polar. Each O-H bond has a dipole moment. Dipole moment is a vector quantity, having both magnitude and direction. Since H2O is a bent molecule, the bond moments do not cancel each other and the molecule has a net dipole moment. Water is thus a polar molecule.

The image at ‘b’ represents the water molecule.