Operating Instructions MA 50
Contents
1. When measuring a pure tone audiogram you assume that the measured hearing threshold is correct But if you recognize that sound is also transmitted through bone conduction over the entire skull it is probable that the opposite ear has also received sound This is called crossover Crossover can also occur when measuring air conduction because a small amount of air conducted sound is received by the skull and transmitted by bone Whether the crossover signal can hear by the opposite ear depends on its Inner ear Tunction Geba _MA50 Fe_11a doc 11 851 406 2 11 11 M Operating Instructions MA 50 MAICO Relevant to crossover is the sound level which is received by the opposite ear The difference between the original test signal at the test ear and the received signal at the opposite ear is called interaural attenuation For bone conduction measurement the interaural attenuation is O to 15 GB Bone conduction crossover is therefore possible even with a slight difference in hearing loss between ears Important Please advise the patient to tell you in which ear he hears the test signal It is thereby easier to detect crossover 4 4 2 Masking theory To ensure that the patient will not experience crossover you must mask the opposite ear Masking increases the hearing threshold of the opposite ear The masking is done with a noise signal which is transmitted by the headphone For pure tone audiometry a narrowband noise is use2. channel by two detented knobs on the left and right of the instrument which can be operated from the side or the top The level steps are 5 dB The signal STIM bar and the frequency up down keys are just beside the level control knobs for easy one handed control of level frequency and signal presentation The bright LED display shows level and frequency for each channel As a result of modern microprocessor technology the MA 50 is easy to use and is extremely reliable The audiometer is designed to be extremely service friendly Automatic test programs make trouble shooting and the yearly calibration as easy as possible PC Interface A serial RS 232C interface for data transfer to a connected computer is built in The optional MAICO audiometry module for NOAH enables the automatic data transfer of all test results of the MA 50 likes tone audiogram For more information see chapter 7 Geba _MA50 Fe_11a doc 4 851 406 2 11 11 M Operating Instructions MA 50 MAICO 3 Getting started 3 1 Unpacking your instrument Your MA 50 was carefully inspected and packed for shipping However it is a good practice to thoroughly inspect the outside of the shipping box for signs of damage If any damage is noted please notify the carrier immediately Carefully remove the instrument from the shipping box Remove the plastic bag from the instrument and inspect the case for any damage Notify the carrier immediately if any mechanical damag
3. control The user of the instrument should perform a subjective instrument check once a week This check can be done following the list for subjective instrument check see next page For your own security you should copy the enclosed list fill it in once a week and store it in your files Geba _MA50 Fe_11a doc 25 851 406 2 11 11 M Operating Instructions MA 50 MAICO Checklist for Subjective Audiometer Testing Clean the ear and head cushion Instrument Untangle all lines when necessary Are the headphone cushion in good condition Ma n ufactu rer If not gt replace Are plugs and leads in good condition undamaged Serial NO Are all controls working properly Is the Patient Response Key working properly if available Exam Iner Check batteries and renew if necessary Test Signal Quality All the test frequencies in the below table indicate typical hearing level and can be changed when necessary Masking B for Buzz tone G for Noise V for signal distortion S for switching masking noise RightEar level Left Ear kHz 0 2505 1 2 B A 6 B 02505 1 2 B M ie iB khz odde t Boor S ft o pot ft ft ft ft fT f Bogh f S S S S S So o OS S ft S S f f poB S S S S S S So pot S ft f f f f BooBHE f f S ST S SSTT pot S f J Bosh S F I I When noise B G V or S is blocked inform the service center When the test tone is heard
4. damage in transit please use the original packing if possible when returning the instrument Within the European Union it is illegal to dispose electric and electronic waste as unsorted municipal waste According to this all MAICO products sold after August 13 2005 are marked with a crossed out wheeled bin Within the limits of Article 9 of DIRECTIVE 2002 96 EC on waste electrical and electronic equipment WEEE MAICO has changed their sales policy To avoid additional distribution costs we assign the responsibility for the proper collection and treatment according legal regulations to our customers Geba _MA50 Fe_11a doc 24 851 406 2 11 11 M Operating Instructions MA 50 MAICO 12 Safety Regulations 12 1 Electrical Safety The MA 50 audiometer is constructed to comply with protection class Il of the international standard IEC 601 1 EN 60601 1 AN Protection from an electric shock is ensured even without the system earth connection The instruments are not intended for operation in areas with an explosion hazard 12 2 Measuring security To guarantee that the audiometer works properly the instrument has to be checked and calibrated at least once a year The service and calibration must be performed by an authorized service center In accordance with the regulations of the EU medical directive we will drop our liability if these checks are not done The use of non calibrated audiometers is not allowed 12 3 Device
5. power cord plugged in correctly Check the power fuses Disconnect the power plug unscrew the fuses a aN alongside the power cord socket and check the B fuses If the wire in the glass vial is broken please insert new fuses 1 A slow blow Picture 21 power socket and fuses Diodes light up but test tone is absent Green STIM LED or does not light Press STIM bar or When the diode lights up and the tone is available the device works in presenter mode Green STIM LED or does light Is level control or set to an audible level position Are the acoustic receivers connected to the correct socket Is the required receiver with button or selected is the correct LED Is the lead connecting the headphones or the bone conductor loose or detective If your instrument still does not work properly after this short check please consult your dealer or service center Geba _MA50 Fe_11a doc 19 851 406 2 11 11 M Operating Instructions MA 50 MAICO 10 Technical Data The MA 50 audiometer is an active diagnostic medical product according to the class Ila of the EU medical directive 0123 93 42 EEC Standards IEC 645 1 EN 60 645 1 Type 3 ANSI S3 6 1996 Type 3 Test Frequencies 125 Hz 250 Hz 500 Hz 750 Hz 1 kHz 1 5 kHz 2 kHz 3 kHz 4 kHz 6 kHz 8 kHz Level step 5 dB level steps Sound Pressure Level AC with earphone Telephonics TDH 39 10 dBHL 1
6. 20 dBHL 500 Hz 4 kHz 6 kHz 10dBHL 115 dBHL 250 Hz 8 kHz 10 dBHL 100 dBHL 125 Hz 10 dBHL 80 dBHL BC with bone conduction receiver Radioear B 71 10 dBHL 70 dBHL 500 Hz 750 Hz 3 kHz 4 kHz 6 kHz 10 dBHL 60 dBHL 250 Hz 10 dBHL 40 dBHL 125 Hz 8 kHz no output speech 10 dBHL 85 dBHL Insert earphone with optional EAR 3A 10 dBHL 120 dBHL 750 Hz 1 5 kHz 10 dBHL 115 dBHL 500 Hz 4kHz 10 dBHL 110 dBHL 250 Hz 10 dBHL 105 dBHL 6 kHz 10 dBHL 95 dBHL 125 Hz 10 dBHL 90 dBHL 8 kHz 10 dBHL 85 dBHL Test Signal Pure tone pulse tone warble tone narrowband noise Modulation Pulse tone 0 5 s on off Warble tone triangular freq devitation 5 repetition rate 5 Hz Functions Tone presenter interrupter Tracking fixed level difference between both channels Warm up time less than 10 min after power on Environment conditions 15 35C 59 95 F operation 5 450C 41 122 F storage Maximum humidity 90 storage and operation Dimensions WxDxH 36x 46 x 15cm 14 2 x 18 1 x 5 9 Weight 4 6 kg 10 1 Ibs with accessories 5 8 kg 12 8 Ibs Power Supply 100 240 V 50 60 Hz 10 Power Consumption app 25 VA Device Fuses 2x 1A slow blow Geba_MAS5O_Fe_11a doc 20 851 406 2 11 11 Operating Instructions MA 50 MAICO Connection plugs Connection Specification power socket left right power 100 2
7. 40 V 50 60 Hz middle prot GND power Tuses 1 A slow blow serial PC interface 1 GND 2 RX 3 TX RS 232 C 5 GND 6 DTR patient response switch Sleeve GND tip in Ri 500 Q BC bone conduction receiver sleeve GND tip out Zpa 4Q Un 8 Veg AC headphone right channel sleeve GND tip out Za 100 Un 1 Vere AC headphone left channel Sleeve GND tio out Z 10 Q Ua 1 Vers FAN A EN FA AN NAN A iB F C D N Ty WV k Picture 22 rear of MA 50 with connection plugs Geba _MA50 Fe_11a doc 21 851 406 2 11 11 M Operating Instructions MA 50 MAICO Calibration values AC Receiver Telephonics TDH 39 Force 4 5 N Reference equivalent threshold Frequency Hz sound pressure level sound damping ISO 389 1 ANSI 3 6 1 with Coupler IEC 318 2 with Coupler NBS 9A dB re 20 uPa dB re 20 uPa _ 45 a E E E Calibration values BC Receiver Radioear B 71 Force 4 9 Reference equivalent threshold Frequency Hz force level air radiation ISO 389 3 ANSI S3 6 1996 mean maximum dB re 1uN dB re 1uN dB 2500007 p00 8 m0 485 485 M000 425A 150000865 E 20000 400085585 e000 4040 573 Geba _MA50 Fe_11a doc 2 851 406 2 11 11 M Operating Instructions MA 50 MAICO Calibration values Insert phone Eartone 3A optional ions enc Nena Frequency Hz sound pressure level sound damping ISO 389 2 ANSI S3 6 1 with paps IEC K with e pa Standard acces
8. 94 s Audiology Desk Reference Roeser Ross J New York Stuttgart Thieme 1996 Auditory Diagnosis Silam Shlomo and Carol A Silvermann San Diego London Singular Publishing Group 1997 Geba _MA50 Fe_11a doc 16 851 406 2 11 11 Operating Instructions MA 50 MAICO 7 Computer interface The MA 50 has a built in serial RS 232 PC interface for data transfer to a connected PC The serial cable to connect the MA 50 with the PC should be a normal non twisted 9 pin extension cable It has a male and a female connector and all wires are direct 1 1 connected It is also sold as monitor extension cable Caution The computer you are using must meet electrical satety requirements such as IEC 950 or UL This is to avoid electrical shock of either the patient or you All test results are online transferred to the PC and stored in the database In pure tone audiometry initially all measured data is transterred as 10 1 000 30 hearing threshold data This iS _ Picture 17 MA 50 display with indicated by the dot left from the pure tone threshold setting center of the LED display see picture 17 10 100 0 80 J To test the uncomfortable level Picture 19 MA 50 display with MCL settin UCL press the test channel selector d key longer than 2 seconds and the dot moves to the center of the LED display All measured data is now transferred as UCL data To test the most comfortable level MCL press the test chann
9. MA 50 MAICO 4 4 4 Automatic masking With the manual masking as described before you have to readjust the masking level every time you change the test signal level The MA 50 has a tracking feature for easy masking Adjust for the test signal using the level control knob then with the masking level control knob adjust for the corresponding masking level Now press the TRACK button The masking level is automatically changed if you adjust the test signal level e g if the test level was 30 dB and the masking level 50 dB and you change the test level to 45 dB the masking level is automatically adjusted to 65 GB Geba _MA50 Fe_11a doc 13 851 406 2 11 11 M Operating Instructions MA 50 MAICO 5 Quick reference guide 5 1 Startup settings Air conduction on both channels Pure tone with a level of 30dBHL on the right ear Narrow band noise with a level of 1O0dBHL on the left masking ear Presenter mode 5 2 Receiver selection Press the RECEIVER key to select the receiver AC BC INSERT The corresponding LED above the key lights Not available receivers will be skipped After a new selection the level will be reset to 30dBHL for the signal and 10dBHL for masking 5 3 Frequency selection Use the frequency keys and to select the frequency The maximum and minimum frequency depends on the receiver you have selected 5 4 Warble tone FM Press the FM key to activate the warble ton
10. MAICO Diagnostic GmbH Operating Instructions MAICO MA 50 MAICO Diagnostic GmbH Salzufer 13 14 D 10587 BERLIN Tel 49 30 70714650 Fax 49 30 70714699 Table of Contents Page 1 VEY CUD O Gs ccesaneeostear onctatetosneseaccas ince cecnetee ssanducueteteerntonuapedarneceusenatucedonnearenss 3 PAD SORE IOWA A EE T E E T E TES 4 F CEO aE pernan EE Ea E i E AEA E E EREE EA E 5 3 1 Unpacking your iNStrUumMent s snusinesiusiusrrerirsrrerrrrrsrrerrrrrerrerrrerrerre 5 3 3 Getting familiar with the MA 50 0 0 cccec ccc eecceceeeeeseeeeeeneseeanesenaneeenans 7 3 3 1 Using the keyboard of the MA 50 cccccccccecccceeeeee ee eeeeeeeeeeanesenaeeens 8 3 3 2 The display of the MA 50 0 0 ccc cccccccccccccccceeeeeeeeeeeeeeaneseeenesenaneeenanesens 8 4 Pure One audiom tiy esseeri nieee Ea a daara 9 4 1 Air Conduction AC Testing 20 cccccceccceccce cece ceeueseue seen eeeueseeaeetaseuneeeaess 9 4 2 Uncomfortable Hearing Level UCL Testing 10 4 3 Bone Conduction BC Testing ccc ccecccceccecceeeeeeeeeeeeseeeeeraestaneeeaeseaes 11 4 4 Masking of the opposite eaf cece cceeecceeeceeeeeseeeeeseeeeeseeueeeeeneeeeenes 11 Ay bes KOSS OV ONG jecteyo sec EE E EE aan aacee sens seaeeacnete 11 4 4 2 MASKING theory 0 cc cece ccc cece eceeeceee eee eeceeeeese este eeeeeeeeeeeseeeeaneeenees 12 4 4 3 Manual Masking ee eee 12 4 4 4 Automatic MASKING s ssnssiusinesiusirerresirsrrerisrrsrrrrrrrrrerr
11. al should make it as easy as possible for you to become familiar with the functions of the MA 50 Please open out the flap of illustrations on the last page The description of the position e g of controls displays and connections found again in the text will make it easier for you to learn how to operate the MA 50 If you have problems or have ideas for further improvements please get in touch with us Simply call Your MAICO team Geba _MA50 Fe_11a doc 3 851 406 2 11 11 M Operating Instructions MA 50 MAICO 2 Description The MA 50 is an audiometer for pure tone audiometric tests It can be used for ENT diagnostics in the office and for mobile audiometry in clinics homes and abroad Tests can be performed using the TDH 39 headphones AC B 71 bone conduction receiver BC or optional insert phones Built in test signals are pure tone pulse tone warble tone and narrow band noise The MA 50 audiometer delivers 11 air conduction AC test frequencies from 125 Hz to 8 kHz with levels from 10 dBy to 120 dBp Bone conduction BC can be tested with 11 test frequencies from 125 Hz to 8 kHz with levels from 10 dBy to 70 dB HL with the standard bone conductor B 71 the frequency range is limited from 250 Hz to 6 KHz The optional insert phones EAR 3A submit levels trom 10 dB to 120 dB with 11 test frequencies trom 125 Hz to 8 kHz The hearing level is controlled independently for the signal and the masking
12. at the masking ear contact the service center Air Conduction Rota r khz 025051 k B ee S p E E E E e Faw Left Left Earpiec fow Earpiec Right Right Earpiec an Earpiec ox x ao x Should is the last measurement of the patient For inverted measurement please reattach the headphone If the frequency difference between Should and Is for one ear averages more than 10 dB contact the SERVICE CENTER Bone Conduction Audiogram RightEar level Left Ear eed EO O E a khz 02505 R B ee ES p p p E ERE TTA ef ff tye dBHV et tt dtd Be FE EE EE EL dBHV If the frequency difference between Should and Is for one ear averages more than 10 dB contact the SERVICE CENTER Geba _MA50 Fe_11a doc 26 851 406 2 11 11 M Operating Instructions MA 50 MAICO Specifications are subject to change MAICO Diagnostic GmbH Salzufer 13 14 1058 Berlin Telefon 49 3070 71 46 50 Telefax 49 30 70 71 46 99 e mail export maico biz MAICO Internet www maico biz Geba _MA50 Fe_11a doc 27 851 406 2 11 11
13. d This noise changes its center frequency according to the frequency of the test signal 4 4 3 Manual masking If you have to mask use the common masking rules See chapter 7 for recommend literature Masking is an important part of practical audiometry It is necessary to be familiar with this topic to avoid errors which would lead to a wrong diagnosis Select the ear you like to test with the channel selector key For the opposite ear narrow band masking noise is automatically set Adjust the required masking level with the levelcontrol knob Notice that the masking sound is continuously presented for effective masking You can interrupt the masking signal by pressing the corresponding interrupter key To mask when performing bone conduction testing place the headphone on the opposite ear so that the receiver is at the correct height the sound output grid exactly faces the Picture 16 correct seating of the ear canal Adjust the headband of the bone conductor headphones The receiver on the side where the bone conductor is placed should sit directly on the cheek bone The marking for air conduction with masking should be done with the symbols A the right side and W the left side on the audiogram form The marking for bone conduction with masking should be done with the symbols the right side and the left side on the audiogram form Geba _MA50 Fe_11a doc 12 851 406 2 11 11 M Operating Instructions
14. e Press the FM key again to switch back to pure tone 5 5 Pulse tone Press the PULSE key to activate the pulse tone Press the PULSE key again to deactivate pulsing 5 6 Test channel selection Press the test channel selector key to select the left or right ear for testing 5 7 Tracking function Press the TRACK key to activate tracking The selected test channel tracks now the masking level at the opposite ear Press the TRACK key again to deactivate tracking Geba _MA50 Fe_11a doc 14 851 406 2 11 11 M Operating Instructions MA 50 MAICO 5 8 STIM Mode selection Press STIM MODE key to switch between continuous presentation and presentation by pressing the STIM bar When in continuous presentation mode the STIM bars and 8 function as interrupters The light above the STIM MODE key is on if continuous presentation is selected Masking noise is always in continuous presentation Press the STIM MODE key again to deactivate continuous presentation Geba _MA50 Fe_11a doc 15 851 406 2 11 11 M Operating Instructions MA 50 MAICO 6 Recommended literature Audiometric Interpretation A Manual of Basic Audiometry Lloyd Lyle L and Harriet Kaplan Baltimore University Park Press 1980 Auditory Disorders A Manual for Clinical Evaluation Jerger Susan and James Jerger Boston College Hill Press 1981 Handbook of Clinical Audiology Katz Jack Baltimore William amp Wilkins 19
15. e is noted This will assure that a proper claim is made Save all packing material so the claim adjuster can inspect it as well Notify your dealer or MAICO when the adjuster has completed the inspection SAVE ALL THE ORIGINAL PACKING MATERIAL AND THE SHIPPING CONTAINER SO THE INSTRUMENT CAN BE PROPERLY PACKED IF IT NEEDS TO BE RETURNED FOR SERVICE OR CALIBRATION All accessories are already packaged in the compartment connected with the MA 50 Please check that all accessories listed below are received in good condition If any accessories are missing or damaged immediately notify your dealer or MAICO Standard accessories 1 Headphone TDH 39 1 Bone conduction receiver B 71 with headband 1 Patient resoonse switch 1 Power cable 1 Audiogram form 50 sheets Calibration of the device The instrument headphones bone conduction receiver as well as the optional insert phone match one another and have the same serial number e g 6631520 Because they have been calibrated with this particular instrument use of other transducers is not allowed If one of the acoustic transducers is replaced the instrument must be recalibrated The use of non calibrated audiometers leads to incorrect measurements Geba _MA50 Fe_11a doc 5 851 406 2 11 11 M Operating Instructions MA 50 MAICO 3 2 Preparing the MA 50 for use The MA 50 with its integrated compartment for the accessories is perfect for portable use The rugged hou
16. el 10 10 00 80 selector button longer than 2 Picture 18 MA 50 display with UCL setting seconds and the dot moves to a position right of the center of the LED display All measured data is now transterred as MCL data Geba _MA50 Fe_11a doc 17 851 406 2 11 11 M Operating Instructions MA 50 MAICO 8 Care and maintenance of the instrument Disconnect the power plug before cleaning To clean the instrument headphones bone conduction receiver loudspeaker and other accessories use a soft cloth dampened with a little warm soapy water or washing up liquid no alcohol or spirits should be used The ear cushions Z of the headphone can be detached for cleaning To remove the ear cushion Z pull it gently from the earphone To assemble the cleaned or changed ear cushion press it on the earphone and make sure that it sits properly The sound outlet hole must be exactly in the middle of the earphone During cleaning please ensure that no liquid runs into the switches level control headphone capsules or loudspeaker openings Picture 20 changing of the ear cushions N Z gt Geba _MA50 Fe_11a doc 18 851 406 2 11 11 M Operating Instructions MA 50 MAICO 9 Trouble shooting If you should find that your instrument is no longer working properly during a test run please check the following points INT A Diodes in the buttons do not light up and there is nothing to see on the LED display a Is the
17. ence the function of the audiometer Therefore the use of these instruments is not allowed in close proximity to the audiometer The test room must be at normal temperature usually 15 C 59 F to 35 C 95 F and the instrument should be switched on about 10 minutes before the first measurement to guarantee precise measuring results If the device has been cooled down e g during transport please wait until It has warmed up to room temperature Picture 1 Transport of MA 50 fp Seen on oe C88 bE g Picture 3 MA 50 in operation Geba _MA50 Fe_11a doc 6 851 406 2 11 11 M Operating Instructions MA 50 MAICO 3 3 Getting familiar with the MA 50 Turn on the instrument with the power switch which is located at the right side of the MA 50 The device performs its initial test and auto calibration If an error is detected the test is stopped and the code of the error is shown on the LED display In this case please contact your local dealer or service If the test is passed the instrument is setup to air conduction and pure tone for the right ear and narrow band masking noise for the left Baco MA 50 s above the receiver and the test channel selector are lighted The 10 is 48 26 frequency is set to 1 kHz and the Picture 4 MA 50 power switch display and selection level to 30 dBy for the right test Buttons for receiver and test channel channel and to 10 dB for the left masking channe
18. ess the FM button and the pure tone will frequency modulate The warble tone can also be pulsed as described before For hygienic reasons it is important to clean the ear cushions of the headphone see chapter 8 4 2 Uncomfortable Hearing Level UCL Testing Testing of UCL can be measured using pure tone stimuli The purpose is to determine the dB level at which the stimuli becomes uncomfortable to the patient This information is valuable tor determining the patient s upper dynamic range limit tor proper hearing aid fittings and for determining symptoms of recruitment Warning Because the UCL test uses high sound pressure levels it is extremely important to perform this test using the utmost caution to avoid damaging the ear To prevent the possibility of extreme discomfort by the patient it is important to start the test with levels near the patients MCL Most Comfortable Level The UCL level is described as the level between very loud and loud perception of the test signal Press the test channel selector 10 10 00 60 oe he eee 4 ae Picture 12 MA 50 display for UCL test left display moves to the center of the display see picture 12 Start as described in chapter 4 1 with a test level of 60 dBy Present the tone brietly max 1s Geba_MA50_Fe_11a doc 10 Picture 13 Bone conductor M Operating Instructions MA 50 MAICO If the signal was recognized by the patient as not uncomfortable increase
19. est signal as described before If the patient doesn t hear the test tone increase the level with the level control knob Proceed with presenting the test signal as described before When you find a stable threshold value note the level and frequency If the MA 50 Is connected to a PC the value was stored with your last STIM presentation Geba_MAS5O_Fe_11a doc 9 851 406 2 11 11 Operating Instructions MA 50 Test through the frequencies Starting at 1 kHz set the higher frequencies first then the lower frequencies Use the frequency up key to select the higher frequencies and use the frequency down key to select the lower frequencies Select the next frequency increase the level again and proceed with presenting the test signal as described before Once all frequencies are tested choose the poorer ear and repeat the hearing threshold test You can do this just by pressing the test ear button The corresponding LED L lights and you test the left ear using the controls on the right side The masking is controlled with the level knob on the left side of the instrument For masking see chapter 4 4 The correct marks in an audiogram are O red right and X blue lett Pulse tone If required the test can also be performed with a pulsed tone Press A button and the pure tone will be switched 0 25 s on and 0 25 s off Warble tone If required the test can also be performed with a warble tone Pr
20. l All these settings 10 1 000 are also shown on the display see picture 5 Picture 5 MA 50 display with initial settings The hearing level can be easily adjusted with the right knob and the masking level with the knob on the left side of the Instrument For optimal convenience these level control knobs are usable from the 10 1000 top or the side of the instrument They are detented in 5 dB steps The STIM bars and are located beside the level control knobs The STIM LED light up when you press the STIM bar to present the test signal The STIM LED lights continuous because the the masking noise is continuous presented The are 14 frequency is changed with up Picture6 MA 50 level and frequency control and down buttons The design of the MA 50 makes it easy to control level signal presentation and frequency with one hand Geba_MAS5O_Fe_11a doc 7 851 406 2 11 11 Operating Instructions MA 50 MAICO 3 3 1 Using the keyboard of the MA 50 All main functions of the MA 50 are directly accessable by pressing fo a single button Following is the description of the functions of each button 1000 frequency up change to next higher frequency frequency down change to next lower frequency FM modulation warble tone changes test signal trom pure tone Byiaico MAS to warble tone receiver selector dy a i changes the receiver from AC to a BC
21. or INSERT if option Picture7 MA 50 keyboard assembled The lighted LED above shows the current selection pulse tone enables pulsing of pure tone or warble tone stim mode changes the signal presentation from presenter to interrupter mode tracking function enables the automatic tracking see chapter 4 4 masking channel selector key selects the right or left test ear 3 3 2 The display of the MA 50 The bright LED Display of the MA 50 shows levels and frequency The display shows the individual levels for the left channel on the left and the right channel on the right The frequency is displayed in the 10 1 000 3 0 middle Also the position of the picture 8 MA 50 display for pure tone HL test dot in the middle indicates the kind of measurement If the dot position is left trom the center HL test is indicated The dot in the center stands for UCL measurement and a dot right from the middle is MCL measurement The example picture 8 shows the initial setting for AC threshold test The right test channel is set to 30 dBy the left masking channel is set to 10 dBu narrow band noise for masking The test frequency is 1000 Hz and the test is a HL measurement dot left from the middle Geba _MA50 Fe_11a doc g 851 406 2 11 11 M Operating Instructions MA 50 MAICO 4 Pure tone audiometry 4 1 Air Conduction AC Testing In the hearing threshold test the hearing threshold of the patient is meas
22. rrrrerrerrrrrren 13 5 Quick reference CS asec areas saeesnee ante vated tecadinasaharcesadendentonslecanieenenaensts 14 Dill ot Al MUL SHUI S E E cn ied apie avec S TEE 14 5 2 Receiver selection 2 0 cece cecceeccc cece ce eeeeeeeeeeee ee eeeeeeee essen eeegeeesneeeaeetaneeenees 14 5 3 Frequency selection 0 2 0 ccce ccc eccc cece cece cece eect ee eeen sees eeeeeeeeneeesneeeeeetaneeenees 14 5 4 Warble tone FM cccccccecececcccececececcesecececeeeesecesaceueesecataveceeeneuteneeterass 14 5 5 Pulse CONC cece cece cece cece cence ee ee eee ce eee ce eeeneee de eeen seed essen eeegeeeaneeeaeeeaeeeenees 14 5 6 Test Channel selection 20 2 0 cccccccc cece cc cceeeeeeeeceeeeeeeeeeeeeeeeeeeneseeneeeeeeeaeeenees 14 Geba_MAS5O_Fe_11a doc 1 851 406 2 11 11 M Operating Instructions MA 50 MAICO 1 Introduction Thank you very much for purchasing a quality product from the MAICO family This MA 50 audiometer is manufactured to meet all quality and safety requirements and has been certified with the CE symbol according to Medical Directive 93 42 EEC In designing the MA 50 we placed particular importance in making it a user friendly device meaning its operation is simple and easy to understand And because MA 50 functions are software controlled upgrading later to new extended measurement functions will be simple and inexpensive That means that you have invested in a device that will adjust to your future needs This user manu
23. sing light weight and the comfortable handle make it easy and convenient to transport the instrument Carry it as shown with the bottom away from the leg That helps protect the front cover from damage and due to the asymmetrical handle position it provides more space for your leg To get started first move the handle under the housing Unlatch the cover by pressing in the two black locks located on the left and right sides near the front of the instrument Open the front cover and rest it on the back cover of the accessory compartment To open the compartment press the two black locks in the upper middle of the instrument Open the compartment cover as seen in picture 2 Take the headphone the bone conduction receiver the patient response switch and the microphone out of the compartment and connect the power cable to power The MA 50 operates with voltages from 96 to 240 V AC 44 Hz to 440 Hz To avoid pinching the cables when closing the cover lay the cables in the slots provided Close the back cover and latch it with slight Picture 2 Portable with open cover pressure The MA 50 should be operated in a quiet room so that the audiometric examinations are not influenced by outside noises For use in noisier environments headphones with optional sound insulation muffs are available Picture 3 MA 50 in operation Electro medical instruments which emit strong electromagnetic fields e g microwaves radiotherapy devices can influ
24. sories 1 air conduction receiver Telephonics TDH 39 1 bone conduction receiver Radio Ear B 71 1 patient response switch 1 power cord 1 pad of audiogram paper 50 sheets Optional accessories Insert phone Part No 4790 audiogram paper 50 sheets Part No 1162 417 Geba _MA50 Fe_11a doc 23 851 406 2 11 11 M Operating Instructions MA 50 MAICO 11 Warranty Maintenance and After Sales Service The MAICO MA 50 is guaranteed for 1 year This warranty is extended to the original purchaser of the instrument by MAICO through the distributor from whom it was purchased and covers defects in material and workmanship for a period of one year from date of delivery oft the instrument to the original purchaser The MA 50 may be repaired and serviced only by your dealer or by a service center recommended by your dealer We urgently advise you against attempting to rectify any faults yourself or commissioning non experts to do SO In the event of repair during the guarantee period please enclose evidence of purchase with the instrument In order to ensure that your instrument works properly the MA 50 should be checked and calibrated at least once a year This check has to be carried out by your dealer When returning the instrument for repairs it is essential to send the headphones as well Send the device to your dealer or to a service center authorized by your dealer Please include a detailed description of faults In order to prevent
25. the level and proceed as described before If the signal was uncomfortable for the patient note the values Proceed accordingly with other test frequencies For hygienic reasons it is important to clean the ear cushions of the headphone see chapter 8 4 3 Bone Conduction BC Testing Bone conduction i e the transmission of sound waves through the skull directly to the inner ear conways information about the Picture 14 correct seating function of the inner ear For a neural hearing of the bone conductor loss the values of air conduction chapter 4 1 and bone conduction are the same In this case a hearing loss of the middle ear can be eliminated Place the bone conduction receiver so that the flat circular side of the transducer Y is placed on the mastoid at the noticeable ledge of the cranial bone behind the auricle see picture 14 The other side of the headband is placed in front of the opposite ear Set the receiver selector to BC Perform the test the same way as for air conduction see 4 1 Enter the measurements for all frequencies on the form connect all points with dotted lines marked on the audiogram form as follows gt right and lt left For hygienic reasons it is important to clean the bone conductor see chapter 8 4 4 Masking of the opposite ear The basics of masking are explained below To begin testing immediately please go directly to 4 4 3 Manual masking 4 4 1 Crossover
26. ured in comparison with the normal hearing threshold for air conduction The test is started on the ear with better hearing The patient should sit at a distance of at least 1 m from the device Eliminate any obstructions which will interfere with the placement of the earphone SA cushions on the ear i e hair eyeglasses Picture 10 Headphone Ensure the headphones are put on correctly Red side on the right blue side on the left Adjust the headband of the headphones so that the receivers are at the correct height the sound output grid amp exactly facing the ear canal Start with the better indicated ear at 1 kHz After 1000 switching on the frequency is automatically set to 1 kHz In the following example we 2 JE assume that the right is the 5g CIE better ear f Set the receiver selector to AC Set the lett level control Baco MAS knob to a value just below expected hearing loss a 3 6 5 88 Explain to the patient 2 amp Ww i i 48 A that he should Dress the button Picture 11 MA 50 controls and display for of the patient response switch _ airconduction threshold test if he just hears the test tone Press the STIM bar for a certain time to present the test tone The STIM LED should light on If the patient hears the test tone the patient response display lights red In this case decrease the level with the level control knob Proceed with presenting the t
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