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Industrial Engineering Department Safety Engineering and Human Factors (Lab) (65589) Report Grading Sheet

Instructor Name:Eng.Alaa AlawnehExperiment # (3):Hearing Test

Academic Year: 2014/2015Performed on:15 /2/2015

Semester: SecondSubmitted on: 22 /2/2015

Students:

1-Yousef Dweikat2- Qasem Alqasem

3-Yazan Breik4-

Evaluation CriterionGradePoints

Objectives Illustrate the aim of doing the experiment.5

Abstract / Introduction Show over all experiment ideas in simple words.10

Apparatus / ProcedureApparatus sufficiently described to enable another experimenter to identify the equipment needed to conduct the experiment. Procedure sufficiently described.20

Experimental Results and DiscussionResults analyzed correctly. Experimental findings adequately and specifically summarized, in graphical, tabular, and/or written form, with explanation to those results.40

Conclusions and RecommendationsConclusions summarize the major findings from the experimental results with adequate specificity. Recommendations appropriate in light of conclusions. Correct grammar.15

ReferencesComplete consistent bibliographic information that would enable the reader to search for references of interest.5

AppearanceTitle page is complete, page numbers applied, content is well organized, correct spelling, fonts are consistent, good visual appeal.5

Total

100

Introduction:Hearing is one of five senses the physiological process of perceiving sound mammalian ears may be subdivided into three parts :- outer , middle , and inner The ear is the organ of hearing and balance it is composed of three divisions:-external. middle and internal the greater part of which is enclosed within the temporal bone.

Objective:The main objective to do this experiment:1- To know how to use the audiometer.2- To know how to draw audio graph.3- And to evaluate students hearing.

The structure of ear and how it work :Sound waves are collected by the outer ear as shown in figure(1) down and are funneled through the ear canal to the eardrum. Sound waves cause the eardrum to vibrate. The three bones of the middle ear transmit and amplify the vibrations to the oval window of the inner ear. Fluid in the inner ear stimulated nerve endings called hair cells. Electrical impulses are sent from the hair cells along the auditory nerve to the brain.The mechanism of hearing Hearing is a series of events in which the ear converts sound waves into electrical signals that are sent to the brain and interpreted as sound. The ear has three main parts: the outer, middle, and inner ear. Sound waves enter through the outer ear and reach the middle ear where they cause the eardrum to vibrate.The vibrations are transmitted through three tiny bones in the middle ear, called the ossicles. These three bones are named the malleus, incurs, and stapes (and are also known as the hammer, anvil, and stirrup). The eardrum and ossicles amplify the vibrations and carry them to the inner ear. The stirrup transmits the amplified vibrations through the oval window and into the fluid that fills the inner ear. The vibrations move through fluid in the snail-shaped hearing part of the inner ear (cochlea) that contains the hair cells. The fluid in the cochlea moves the top portion of the hair cells, called the hair bundle, which initiates the changes that lead to the production of nerve impulses. These nerve impulses are carried to the brain, where they are interpreted as sound. Different sounds move the hair bundles in different ways, thus allowing the brain to distinguish one sound from another, such as vowels from consonants.

Figure 1: Structure of our ear

Audiometer :DefinitionAudiometer is the testing of a person's ability to hear various sound frequencies. The test is performed with the use of electronic equipment called an audiometer. This testing is usually administered by a trained technician called an audiologist.

Figure 2 : The Audiometer

Audiometric is the testing of hearing ability. Typically, audiometric tests determine a subject's hearing levels with the help of an audiometer, but may also measure ability to discriminate between different sound intensities, recognize pitch, or distinguish speech from background noise. Acoustic reflex and otoacoustic emissions may also be measured. Results of audiometric tests are used to diagnose hearing loss or diseases of the ear, and often make use of an Audiogram.About its applicationThe basic hearing test or audiogram tests one's ability to hear pure tones in each ear. Best results are obtained by a trained audiologist in a special soundproof testing booth. Simple tests, such as ones done in many schools, may be useful for screening, but a careful audiogram is necessary for accurate diagnosis of most hearing problems.A complete audiogram will test both the bone conduction (the ability to hear a sound when it transmitted through bone) and the air conduction (the ability to hear a sound when it transmitted through air). A comparison between these two types of conduction can be very useful in localizing which part of the hearing mechanism is responsible for the loss. In particular, the test is useful in determining if the loss is due to a problems with the portion of the middle ear that conducts sound from the ear canal to the inner ear (in which case it would be called a "conductive" hearing loss) or if it is due to the inner ear or the nerve that conducts the sound signals to the brain (in which case it would be called a "sensorineural" hearing loss).

The results of audiograms are most often displayed in graph form. This graph shows the amount of hearing loss expressed in units called decibels at different sound frequencies (also called Hertz). High frequencies correspond to high tones, and low frequencies are low tones. Most audiograms go from around 250 hertz to 8000 hertz. A loss up to 20 decibels on this graph is considered "normal". Hearing losses over 20 decibels are considered abnormalHow Audiometer Work : Audiometer apparatus comprises an electrostatic transducer having insulated electrodes for application to the skin on the head of a patient and driven by an ultrasonic frequency carrier signal generated in a series resonant circuit including the impedance of the body tissues between the electrodes, the carrier frequency being determined by the series resonant circuit. The amplitude of the carrier is modulated at an audio frequency, and operating parameters such as the magnitude of the current fed to the electrodes and the modulation frequency are controlled automatically in response to preselected values preset therein. Current and modulation frequency values are preset stepwise into a manually adjustable preselectors having detents formed by cooperating magnetic elements establishing successive rest positions corresponding to steps to which the preselector may be set. The preselector is formed with spaced apart segments disposed to cooperate with a pair of optointerruptors to cause the latter to generate stepping pulses and pulses indicating the direction of adjustment of the preselector. Classification of for sound level:- As we mentioned before there are some evaluation for the reading and this must compare with the standard data in the next table the data was explained in ranges:

Table (1): Shows The Relationship between the sound level and degree of hearing loss.Sound levelDegreeof hearing loss

0-20Normal

20-40Mild

40-60Moderate loss

60-90 Severe loss

90 and aboveVery bad

Methodology: The reading was taken for every student who take the reading by using the audiometer in approximately good conditions and record the data which appeared in the audiometer The audiometer graph was established for every student according to his reading The student compare his reading to the standard level and evaluate his hearing

Conclusions and RecommendationsThe Results For Male from the Audiometer was as follow :Figure (3) Shows the reading for male

Table (2) : Shows The Readings for male Frequency (H)LeftRight

50050 m 50 m

100050 m40 m

200050 m50 m

300050 m-

400050 m50 m

600045 m50 m

800050 m50 m

The Results For female from the Audiometer was as follow :Figure (4) Shows the reading for femaleTable (3) : Shows The Readings for femaleFrequency (H)LeftRight

50040 m 40 m

100035 m35 m

2000-40 m

300045 m-

4000--

600040 m40 m

800030 m30 m

Differences between male and female hearing :The best frequency of the female antenna is around 230 Hz; that of the male is around 380 Hz, which corresponds approximately to the fundamental frequency of female flight sounds. The antennal hairs of males are resonantly tuned to frequencies between approximately 2600 and 3100 Hz and are therefore stiffly coupled to, and move together with, the flagellar shaft when stimulated at biologically relevant frequencies around 380 Hz. Because of this stiff coupling, forces acting on the hairs can be transmitted to the shaft and thus to the auditory sensory organ at the base of the flagellum, a process that is proposed to improve acoustic sensitivity.

References:[endnoteRef:2]1. http://www.google.com/search?sourceid=navclient&ie=UTF-8&rls=GGLR,GGLR:2005-41,G. [2: ]

2.http://depts.washington.edu/hearing/Hearing%20Loss.3. http://images.search.yahoo.com/search/images?4. http://depts.washington.edu/otoweb/patients/pts_specialties/pts_ .5. http://www.answers.com/topic/audiometry

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