DAILY BIOLOGIC CHECK OF AUDIOMETERS

Transcription

1 DAILY BIOLOGIC CHECK OF AUDIOMETERS An audiometer must be checked before each day of use or if a problem is suspected with the equipment during use. After the audiometer is turned on, the operator should listen to the signal at different dial settings through each transducer that may be used in testing. In order to do a daily biologic check, the operator should: Check the cords for signs of wearing or cracking. Check all connection points for secure insertion. Check the audiometer for loose dials or dials that are out of alignment. Check that the earphones are securely attached to the headset. After putting on the headsets, present a tone and make sure it comes through the appropriate earphone. Turn the attenuator dial from minimum to maximum levels and listen for increases and decreases in loudness. Be sure to increase the attenuator to high intensity levels. In addition to presenting the tone at these high intensity levels, allow the tone to be absent to listen for hum. For screening purposes, check the screening levels to be used at each frequency. Make sure that the sounds, which the client is expected to hear, can be heard in the environment. If the equipment is to be used for threshold testing, then the threshold of the clinician (or a person with known thresholds) should be checked. Turn the frequency dial with the attenuator set at a comfortable loudness and listen to each frequency. Jiggle the earphone cords and listen for continuous tone presentation. A defective cord will produce static or cause the tone to be intermittent. All transducers that will be used in testing must be checked. In all of the above situations listen for audible clicks, discontinuous presentation of the tone, crosstalk between the earphones, static, hum, background noise, a dead earphone, or any undesired interference with the presentation of the tone. If problems exist that cannot be solved, then testing cannot be done. Document the quality control data on the Audiometer - Daily Listening Check form. Students and clinical educators are responsible for the biologic check of the screening audiometers. Students will be assigned to do the daily biologic check of the equipment in the Audiologic Suite. Completed forms are filed in the Calibration Book in the Audiologic Suite.

2 WAIT, DON T TOUCH THAT DIAL UNTIL YOU HAVE 1. Checked the earphones and bone oscillator cords for signs of wear. 2. Jiggled the cords while listening to a tone to see if the signal is intermittent. Check each earphone. 3. Listened for audible clicks through each earphone when the dial switches are manipulated. 4. Listened for static hum when the tone is present or absent (at 20 and 50 db HL). Run your fingers along the cord while listening especially checking where it enters the earphone. 5. Listened for "cross-talk" between earphones. These are sounds that are heard in the opposite earphone from the test ear. 6. Listened to the signal as the attenuator dial is turned from maximum to minimum to insure linearity and loudness perception appropriate to dial changes through each earphone. 7. Checked for loose or out-of-alignment dials. 8. Checked all connection points for secure insertion. 9. Cleaned the earphone cushions and headband. Check for any signs of wear or cracking. 10. Checked an adult with normal hearing to ensure the screening levels are audible. Listen for room noise while wearing the headsets. 11. Documented the results on the Daily Listening Check form. 12. Reported any equipment problems to the audiologist to arrange for repairs.

3 CARE AND HANDLING OF THE AUDIOMETER Avoid exposing the audiometer to extreme temperature. Store in a cool, dry place. Do not drop the audiometer. Handle the audiometer with care. Secure the audiometer within the case. Fasten the case securely. Place the audiometer in the car with a seat belt or place it securely on the floor. Keep the audiometer covered when not in use to avoid dust. Wipe the audiometer clean with a soft cloth. If the audiometer has a bone oscillator, secure it in foam rubber for traveling. Never force the dials or the tone interrupter switch. They should turn freely and quietly. If there is a problem, repair is needed. The earphones and headband must be cleaned carefully. Keep cleaning solutions out of the diaphragm or center of the earphone. Check the earphone cushions for cracks. Do not twist the electrical cords or the cords to the headphones. Keep the cords untangled. Never bend or twist the headphone cords where they enter the earphone. Make certain cords and wires are stored in the appropriate compartment and are not hanging outside the case. Refer to "The Handling of Earphones." Audiometers must be electroacoustically calibrated to meet the current ANSI standards at least annually and when the examiner suspects a problem. The last date of electroacoustic calibration should be noted on the audiometer.

4 TROUBLESHOOTING THE AUDIOMETER PROBLEM Audible Click/Static/Hum? Press interrupter bar and elicit tone Cross Talk? Present a 70 db HL continuous tone through one earphone Low Intensity Function of the Attenuator? Present 1000 Hz tone at 30, 25 and 20 db HL Cords, Connections to Phones? Present a 50 db HL continuous tone through each earphone Frequencies? Present a 60 db HL continuous tone changing the frequency dial through the octaves Linearity of the attenuator? Present a 2000 Hz tone at 90 db HL, decrease intensity in 5 db steps Matched earphones? Switch signal from one phone to the other REPAIR IS NEEDED IF......sounds other than pure tones are heard...the tone can be heard in the opposite earphone...the tone is not heard at the intensity levels expected...static, crackling, hum, or intermittent sound is heard...the frequencies do not sound as expected...the tones do not get steadily softer...the signals are not equal in intensity At least annual electroacoustic calibration to meet current ANSI standards of every audiometer is required. If a problem is noted, repair and additional electroacoustic calibration is needed.

5 THE HANDLING OF EARPHONES Care must be taken in handling audiometer earphones. They are delicate devices designed to perform a task requiring great sensitivity. 1. The internal construction of earphones makes use of very fine wires. If the earphones are mistreated or handled roughly, these wires may break. 2. Damage can occur if the earphones are placed face down on a table and pressed downward until the cushion is flattened. In this case a quantity of air will be trapped and pressed against the earphone diaphragm resulting in damage. 3. Damage can be caused by slapping an earphone against an open hand or against the other earphone. 4. Earphones can be damage by sharp objects, which may pick holes in the diaphragm. 5. Dropping an earphone severely jars the internal mechanism. Dropping the earphones can cause permanent damage or change the response of the earphone. 6. The earphones are an integral part of the audiometer. They must produce a particular sound at the appropriate level. In order to accomplish this, the audiometer must be calibrated with a particular set of earphones. Another set of earphones cannot be substituted without compromising the accuracy of testing. Whenever the earphones are replaced, the audiometer must be recalibrated.