Portable Audiometer Calibration System March 2012 BRK_4135 BRK 4135
User Manual: BRK_4135
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Portable Audiometer Calibration System Type 9729-W-011 … Easy, flexible and reliable PRODUCT DATA The Type 9729-W-011 Portable Audiometer Calibration System is an easy, flexible and reliable solution for automated calibration of audiometers to IEC and ANSI standards. The system performs the tasks ranging from basic standard audiometer testing with fully automated procedures to advanced customized tests. Audiometer certification is the primary focus, but the system is designed to accommodate the everyday needs of hospitals and clinics as well as those of calibration and metrology laboratories. Other fields of use are audiometer research & development and factory production testing. The system is build around the powerful sound level meter and analyzer Type 2250. It utilizes the precision of this Class 1 measuring instrument and experience in calibration to provide simplicity of use. The Type EN-2252 software with integrated database takes care of test procedure execution as well as all house-keeping data including client e-mail reminders for next calibration. USES AND The calibration system is not limited to any specific brand or type of audiometer, but can calibrate any audiometer that complies with relevant ISO standards. The interface with the variety of audiometers is secured by using Brüel & Kjær family of top-class couplers, such as 2cc Click-on Coupler Type 4946, the artificial ears Type 4152 or 4153 and the artificial mastoid Type 4930. The system can be configured for inhouse calibration services or production tests as well as for use in the field, without compromising neither accuracy nor stability. FEATURES Uses Calibrate any type of audiometer fulfilling IEC 60645 and ISO 389 series standards as well as ANSI/ASA S3.6 and S3.7. Calibrate Headphones, Inserts, HF phones, Bone Oscillators and Tympanometers Free field calibration (audiometry test room) Semi- or fully automated procedures execution. Automatic correction for microphone and artificial Features Calibration procedures based on international standards for air conductive and bone conductive transducers. Multiple test procedures. Tracking of calibration equipment inventory and mastoid sensitivity deviations. Data on operators, customers, audiometers, tests and test equipment is managed in one database. Data can be retrieved by a range of query parameters. calibration date. Audiometer adjustment instructions Customized calibration reports Calibration reminder via e-mail. Portable Audiometer Calibration System Type 9729-W-011 Calibration..? The basic aim of acoustic audiometer calibration is to define the audiometric zero for the chosen earphone. This can be performed using human volunteers or an artifical ear. There are different types of audiometer output transducers: 1. Ear phones 2. Bone vibrator 3. Loud speaker (free-field) Output transducers for audiometers cannot be replaced or changed without calibrating the whole equipment. Calibration of the audiometer involves calibration of the audiometer proper, of ear phones, and of bone vibrators. The calibration procedure and set-up for bone vibrators is the same as for earphones except for the basic measuring device. Figure 1. Main menu of the EN-2252 software —a simple and intuitive user interface with all functionalities For absolute acoustic calibration the audiometer should be calibrated using an artificial ear, a special measuring microphone designed for that purpose and a known sound pressure level. Accurate and reliable measurements are fundamental to characterise and quantify hearing loss, and consequently for selection of hearing aids and for general Audiometer Calibration health and safety monitoring. The purpose of any calibration measurement is to check that the Prober calibration ensures that the measurement equipment is meas- measurements are consistent, no matter where the they are carried uring correctly. Regular testing and calibration of an audiometer is out. The system calibrates audiorequired to maintain maximum meters using an ear simulator measurement accuracy. system. It includes an artificial ear for testing air-conduction hearing mechanisms. This device consist of a calibrated microphone with an associated coupling volume open on one side allowing application of headphones when testing. For testing bone-conduction hearing mechanisms, an artificial mastoid is utilised. This device uses a series of rubber layers to couple the bone-vibrator to a force transducer. The device mimics the way in which sound is transferred through the mastoid part of the human temporal bone to which the bone-vibrators are applied when testing. Figure 2. Set-up of 9729-W-011 Portable Audiometer Calibration System fO n / o f 2 Type 9729-W-011 Portable Audiometer Calibration System System Instrumentation The calibration system is based on Hand-held Acoustic Analyzer Type 2250 and the Audiometer Calibration Software Type EN-XXXX. Acoustic Analyzer The 9729-W-011 Portable Audiometer Calibration System is based on the Type 2250 Hand-held Acoustic Analyzer. Type 2250 is a compact and robust handheld instrument, which can host a number of software modules. Sound Calibrator Sound Calibrator Type 4231 is a pocket-sized, battery operated class 1 sound source. The calibration frequency is 1000Hz (the reference frequency for the standardised international weighting networks) with a calibration pressure of 94 ±0.2 dB re 20 μPa is equal to 1 Pa or 1N/m2. Artificial Mastoid Artificial Mastoid Type 4930 is designed for the calibration of bone conduction hearing aids and bone vibrators used in audiometry. It mechanically simulates the human head, incorporating a built-in force transducer to monitor the output of the device to be calibrated. The artificial mastoid ensures longterm stability and accurate correspon-dence with the mechanical characteristics of the human mastoid. Coupler Type 4946 2 cc Click-on Coupler is intended for measurements on all types of headphones and hearing aids. The design is optimised for quick and easy use in the laboratory and the field. It fulfils the requirements of the ANSI S3.7 (1995) and IEC 60318-5 (2006) standards. A wide range of ear-mould simulators click on to the coupler body, making changing to different headphone or hearing-aid designs easy. Artificial Ear Artificial Ear Type 4153 fulfils the requirements of IEC 318 and has an acoustical impedance basically similar to that of the human ear and allows circum-aural earphones calibration. The acoustic coupler contains three volumes (V1 = 2.5cm3, V2 = 1.8cm3 and V3 = 7.5cm3) acoustically connected in parallel by means of a narrow annular slit and four parallel holes. The Artificial Ear Type 4153 consist of an acoustic coupler, a main housing containing the sockets for the connection of a condenser microphone and a base plate with a mechanism for clamping the object being tested. The Artificial Ear is isolated from shock and vibration by means of three soft rubber feet. Artificial Ear Type 4152 has been designed for measurements in the audiometric and related fields. The primary function is the calibration of supraaural earphones used in audio-metry in complaince with IEC 60318-2. 1” Microphone Type 4144 is a 1″ pressure-field microphone and the pressure frequency response is flat over a wide frequency range. Hence no correction is needed to the pressure response below 8 kHz. The use of pressure-field microphones is recommended where measurement of the local pressure is of interest, for instance for coupler measurements. The stability of Type 4144 combined with its low inherent noise and high sensitivity makes it the perfect choice for coupler measurements. 1/2” Microphone Type 4192 is a ½″ pressurefield microphone designed for high-precision coupler measurements. Being externally polarized, Type 4192 must be used with a classical preamplifier. Externally polarized microphones may be used at higher temperatures without severe changes in sensitivity. 3 Portable Audiometer Calibration System Type 9729-W-011 complete with both 6cc and 2cc coupler, preamplifier, micro-phone, and adaptor to 1 inch and ½ inch microphones. The unique ½ inch microphone adaptor design enables very easy and safe calibration of the coupler. Simply unlock the adaptor and pull out the ½ inch microphone, with grid and preamplifier, and Calibration set-up for Air Conduction Headset mount it in Sound Calibrator Type 4231 or it is important to calibrate down to any other Brüel & Kjær acoustic Coupling the earphone low hearing thresholds, Octave or calibrator. When using a 1” Acoustic calibration consists of One-Third Octave Band Filters are microphone, the microphone measuring the output of the protection grid must be mounted used to reject ambient noise earphones using a standardized before calibration. microphone inside a standardized picked up in the coupler. The It is important to ensure that coupler called an Artificial Ear. As Artificial Ear Type 4152 comes fO n/ of 4 Type 9729-W-011 the earphone is well coupled to the sound level meter and that there are no leaks that would cause inaccurate sound pressure level readings. The earphone and weight should be placed on the coupler. The audiometer should be set to produce a continuous signal at 70 dB HTL at the lowest test frequency (125 Hz on clinical audiometers, 250 or 500 Hz on type 3 or 4 pure-tone airconduction audiometers). The earphone is then adjusted on the coupler to produce the highest sound pressure level reading on the sound level meter. Then the earphone and weight are removed and the process is repeated. The same reading should be obtained. If so, the earphone should remain on the coupler for the rest of its calibration. If not, Portable Audiometer Calibration System Calibration set-up for Bone Conduction Headset the earphone and weight should be removed and the process should be repeated until a sound pressure level reading is duplicated on successive placements and adjustments. fO n /o f 5 Portable Audiometer Calibration System Easy, flexible, & reliable The 9729-W-011 Portable Audiometer Calibration System: reduces typing errors by avoiding manual data entering reduces the time needed for audiometer calibration prevents errors caused by incorrect or ignored corrections for microphone or mastoid The system includes a professional database for: Customers Audiometers Procedures Reports House keeping data Instrumentation Corrections and reference values Start Audiometer Calibration in 9 simple Steps... 1 Connect equipment Set-up the calibration system by connecting the relevant components and the instrument to be calibrated into a measurement chain. 2 Enter client data Select client and associated audiometer from database. If customer does not exist in database enter information including audiometer and accessery data (type and serialno. etc). 3 Select procedure Select calibration test or combination of calibration tests. 4 Enter atmospheric data 5 Calibrate system 6 Calibrate audiometer 7 Adjust audiometer 8 Recalibrate audiometer 9 Create report Enter temperature, humidity and air pressure - data obtained from public sources. Calibrate the measurement chain. Use the reference sound source and include corrections for microphone and mastoid obtained from an independent calibration laboratory. Microphone chain sensitivity correction value is defined and saved for each calibration. Calibrate the audiometer. The calibration consists of 3 steps: 1. Calibration - deviations are calculated: the difference between expected values and measured values. 2. Adjustment - the audiometer is adjusted to meet expected values. 3. Recalibration, to ensure the correctness of the adjustment. Use a query to retrieve calibration results from the database and generate a report using a predefined template. Finish Step 1: System Set-up The 9729-W-011 Portable Audiometer Calibration System comes in a robust and handy carrying case containing all instruments, cables and adaptors needed for testing and calibrating audiometers—all needed in addition is a PC and a USB or LAN connection. The calibration system is setup by connecting the relevant components and the instrument to be calibrated into a measurement chain. The audiometer under test is connected via LAN or USB interface. The set-up is configured according to the options of the system (and optional accessories at hand) and to the tests to be performed (see figure 2 and 3). 6 Type 9729-W-011 vibrators, microphones, mastoids and operators are handled by a SQL database. It is of major benefit to have all data stored in a well-defined and organised form, which facilitates retrieval, editing and updating. An additional safety feature is the regular software notification to produce a database back-up—in case of computer failure all data are preserved. Prior to starting the actual calibration, the operator must enter Step 2: Client Data Data management is a critical part customer information, select calibration procedure and specify the of the calibration process and a instruments used. Client and assostrong feature of the calibration ciated audiometer is selected from software. Measurement data, rethe database. If the customer ports, customer data, inventory does not already exist in the datadata, audiometer data, procedures, corrections for headphones, base, information is entered, inFrom unpacking to reporting a basic calibration—including system calibration—only takes 10 minutes. Step by step the calibration software guides the operator through the preparation procedure—all in an intuitive and logical order. During calibration only the audiometer is operated by the calibration technician—the 2250 is controlled from the software. Type 9729-W-011 cluding audiometer and accessories data such as type, serialnumber etc. The acoustic analyzer is recognized by its serial number and even more importantly by installed software (Active Template). The most frequently used standardised headphones and vibrators are available in the database as default. Additional equipment can be added by the user and correction values entered as required. Microphone and mastoid calibration corrections can be imported from a USB key or entered manually. An example of a correction graph is seen in figure 5. Step 3: Procedure An audiometer calibration task incorporates several tests to be selected depending on the type of audiometer. All acoustic admittance instruments use a probe tone that must be calibrated for at least frequency, SPL and distortion. The operator can select from a range of tests: Pure tone (Air and Bone conduction level) Masking level (Narrow band) Masking level (Broad band) Attenuator linearity Frequency Total Harmonic Distortion (THD) Narrow band cut-of frequencies and bandwidth Portable Audiometer Calibration System Figure 3. The EN-2252 calibration software guides you through all steps of the calibration procedure Apply calibration level 94.0 dB @ 1000 Hz to the measurement microphone inside 4152/4153, using BK 4231 acoustic calibrator. by the user (in reference to standards in question). Corrections for used transducer (microphone and/or mastoid) are One, more or all supported tests automatically read from the datacan be included in the calibration base and taken into account for task. Several tests can be merged into one procedure (e.g. Pure tone calculation of the expected result. All calculations are performed first, Insert second and Mastoid by the calibration software and third). presented in a table as well as Each set of tests is usergraphically to provide overview. defined—the operator can select During pure tone level calibrathe frequencies at which the tests tion, THD and frequency are siare to be executed. All tests are multaneously measured and calcompared to limit values defined culated. Rise Time / Fall Time Free-field calibration Tympanometer calibration Figure 4. A new client is added to the database—client data can be reused for other audiometers or when next calibration is due 7 Portable Audiometer Calibration System Type 9729-W-011 Figure 5. Microphone calibration corrections example —Brüel & Kjær Type 4144 Step 4: Atmospheric Data The environmental conditions of the calibration have to be documented. The levels of temperature, air humidity and air pressure are entered and will be included in the final calibration report. These data can be obtained from public sources. Figure 6. Audiometer calibration in progress - coloured dots indicate measurement status 8 Step 5: System Calibration Traceability of measurement results is an integral part of the calibration procedure. Traceability is obtained by measurement chain calibration at the beginning of each audiometer calibration. Type 4231 is used as the reference sound source producing 94dB at 1kHz—the software automatically includes corrections for microphone and mastoid obtained from an independent calibration laboratory. The microphone chain sensitivity correction value is defined and saved for each completed calibration. The EN-2252 Software constantly monitors the validity of calibration equipment in use. Calibration can start as soon as these conditions for correct calibration documentation are fulfilled. Type 9729-W-011 Steps 6, 7 & 8: Calibration When all relevant data are in the database, it is only a matter of selecting the calibration equipment and the audiometer to be tested, and calibration is started. The calibration of an audiometer is performed in three steps: 1. Calibration deviations are calculated: the difference between expected values and measured values. 2. Adjustment - the audiometer is adjusted to meet expected values. 3. Recalibration - the audiometer is calibrated once more to ensure the correctness of the adjustment. Online guidance eases the calibration and prevents the operator from missing important steps or taking incorrect actions. Each time the operator needs to intervene while calibration is in progress, a window with clear and instructive information will appear. Any deviation exceeding limit value displays an information window with the options to repeat or accept the result. Results which are out of tolerance limits get red light in front of the step in question. During semiautomatic calibration, only the audiometer is operated by calibration technician. Intervention with Type 2250 is not needed at all—it is controlled from the software. The calibration software constantly monitors the calibration validity of client audiometers and automatically sends out a notice on expired calibrations at start-up or on request. Portable Audiometer Calibration System Figure 7. Audiometer adjustment instructions creating report or just to be viewed on the screen. A query function provides capability to retrieve only the calibrations fulfilling specific criteria. Selected calibrations can be examined on the screen or sent to Excel or Word using either a predefined or customer defined reporting template. Figure 8. Reporting example —part of calibration certificate Step 9: Reporting Calibration results are saved in the database and available for 9 Portable Audiometer Calibration System Type 9729-W-011 fO n /o f dB fOn /Of 10 +20 Free Field calibration Pure tone audiometry deliver and important information related to the loss of human ear sensitivity. It is a good indicator for the candidates for hearing aid. However, practice has proven that just increasing the hearing sensitivity is far from satisfactory as the reasons for hearing impairment can lie in different sections of the hearing chain. Therefore it is necessary to conduct another test which reveal not only what sound a person can detect, but more important how much this person can actually understand—a speech audiometric test. When speech audiometry is conducted in a test room or booth using loudspeakers exact conditions for the test must be provided. It is important to check and calibrate the sound level at the reference point (the point where the head of the test person is), check and calibrate the homogeneity of the sound field around reference point, measure THD, linearity and frequency response of the audio system. The loudspeaker should be head-height of the seated listener, and directed towards the reference point. In absence of the test subject the sound pressure levels 0.15 m above, below and to the left and right of the reference point should not vary by more than 1 dB from those predicted by the inverse square law. Mesurements for free or quasi-free sound fields are specified by ISO 8253-2. The standard describes the characteristics of free-field and diffuse field characteristics and the procedures and conditions of use for sound field audiometry. Figure 9. System set-up for free-field audiometer calibration or audiometric test room / booth verification. Tympanometers - Impedance audiometers Impedance is measured by using a probe to present a sound of 226 Hz. into a cavity like the human ear. This produces different SPLs depending on the volume of the cavity of the ear. By measuring the SPL, the equivalent volume can be established, and by tracking the changes in SPL, the equivalent changes in the cavity can be identified The tympanometer should be tested regularly as the probe is very fragile and possible impact on the transducer will affect measurements. The complete system has to be calibrated at least once a year. The calibration is divided into two parts: 1. The instrument itself, which includes the air system 2. The software, which involves adjustments of different parameters via soft keys. The EN-2252 software guides the operator through the specific tympanometer calibration process: probe calibration, compliance and reflex, manometer and Ipsilateral Pure Tone level. The calibration also includes the parameters that apply for Pure Tone Audiometers (linearity, frequency, THD etc). The technical requirements for tympanometers are specified in IEC 60645-5 and for the acoustic part in IEC 60645-1. Calibration and test procedures are specified in IEC 1027 and ANSI S3.39 - 1987. Type 9729-W-011 Standards: EN-2252 Audiometer Calibration Software and Sound Analyzer Type 2250 conforms with the relevant parts of the following standards: IEC 60645-1:2001 Electroacoustics - Audiological equipment - Part 1: Pure-tone audiometers ANSI/ASA S3.6-2010 Specification for Audiometers ISO 389 Acoustics - Reference zero for the calibration of audiometric equipment IEC 60318-3 1998 Electroacoustics - Audiological equipment - Acoustic coupler for the calibration of supra-aural earphones used in audiometry ANSI S3.39-1987 (R 2007) Specifications for Instruments to Measure Aural Acoustic Impedance and Admittance (Aural Acoustic Immittance) Calibration and test procedures are specified in: ISO 8253-1:2010 Acoustics - Audiometric test methods - Part 1: Pure-tone air and bone conduction audiometry ISO 8253-2:2009 Acoustics - Audiometric test methods - Part 2: Sound field audiometry with pure-tone and narrow-band test signals ISO 8253-3:1996 Acoustics - Audiometric test methods - Part 3: Speech audiometry Portable Audiometer Calibration System IEC 60645-5:2004 Audiometric equipment - Part 5: Instruments for the measurement of aural acoustic impedance/admittance. ANSI/ASA S3.7-1995 (R 2008) Method for Coupler Calibration of Earphones Calibration options: The calibration options available with this Portable Audiomter Calibration System based on Brüel & Kjær Types 2250 or 2270 can cover: Pure tone (Air and Bone conduction level) Masking level - Narrow band (BZ-7230) Masking level - Broad band Attenuator linearity Frequency (BZ-7230) Total Harmonic Distortion (BZ-7230) Narrow band cut-of frequencies and bandwidth (BZ-7230) Rise Time / Fall Time Free-field calibration (BZ-7230) Tympanometer calibration (Manometer required) ORDERING INFORMATION 9729-W-011 Calibration System using Supra-aural Earphones 2250-B - Hand Held Analyzer with Sound Level Meter and Frequency Analysis Software 4153 - Artificial Ear / Ear Simulator (IEC 60 318 coupler without microphone & preamplifier) 4192 - 1/2" Pressure-field Microphone, 3Hz to 20KHz, 200V Polarization AO-0645-D-100 - Cable, Microphone, circular-1B 7-pin (F) to circular-1B 10-pin (M), 10m (33.3ft),max.+90°C (194°F) 4231 - Sound Calibrator Class 1 and LS, 94 and 114 dB, 1 kHz BK-XXXX - Suitcase/transportation case EN-2252 - Audiometer Calibration Software 4946-Q-002 - 2CC Click-on Coupler for QC w/o microphone and preamplifier DB-3869 Ear Plug Simulator with Tube Stud for BTEs 9729-W-012 (9729-W-011 Calibration System with add-ons for Bone Vibrators) 4930 - Artificial Mastoid JJ-2617 - Input adaptor,1/2" microphone to microdot BZ-7230 - FFT Analysis Software AO-0038-D-005 - Cable super low-noise,10-32 UNF (M) to 10-32 UNF (M),0,5m (1,7ft),max.+250°C (482°F) Optional 4152 - Artificial Ear / Ear Simulator (6cc coupler without microphone & preamplifier) 4144 - 1" Pressure- field Microphone, 3Hz to 10KH,200V Polarization Pressure meter Tube kit 4955 - ½” Low Noise Microphone system 5Hz to 20kHz, External Polarized ZE-0948 - USB Audio Interface 11 Portable Audiometer Calibration System Type 9729-W-011 Benefits: Truly portable—easy to carry Easy to use—no special skills required Automated calibration and reporting On-line calibration instructions Automated correction of all instruments SOUND AND VIBRATION - CONTACT BRÜEL & KJÆR Traceable measurements and validity monitoring Easy data-handling—storage and retrieval Compliance to standards IEC 60645, 389 and 8253 Full flexibility for professional use Please, contact your local Brüel & Kjær representative for more information: Brüel & Kjær Sound & Vibration Measurement A/S Export Sales Skodsborgvej 307 DK-2850 Nærum, Denmark Phone: +45 7741 2000 Fax: +45 7741 2015 E-mail: export@bksv.com www.bksv.com HEADQUARTERS: Brüel & Kjær Sound & Vibration Measurement A/S • DK-2850 Nærum • Denmark Telephone: +45 7741 2000 • Fax: +45 4580 1405 • www.bksv.com • info@bksv.com Local representatives and service organisations worldwide EXPORT SALES, MARCH 2012 This product is for sale in Eastern and Central Europe, the Middle East and Africa. For countries in other regions contact the local Brüel & Kjær office.
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