173 Neb. Admin. Code, ch. 7, Attachment 2A
HEARING SCREENING (PURETONE AUDIOMETRY) COMPETENCIES
Essential Steps for Accurate Measurement
COMPETENCY | KEY POINTS |
1. Assess environment for ambient background noise that will disrupt screening. | Conduct screening in an environment with minimal visual and auditory distractions. Ambient noise levels must be sufficiently low to allow for accurate screening. If a suitable environment cannot be located for screening, the screening results are not valid. The parameters of screening should NOT be changed in order to accomplish screening at sound levels other than 20dB. For screening environments, ambient noise levels should not exceed 49.5 dB at 1000 Hz, 54.5 dB at 2000 Hz, and 62 dB at 4000 Hz when measured using a sound level meter with octave-band filters centered on the screening frequencies. These levels are derived from consideration of ANSI (1991) standards for pure-tone threshold testing, and are adjusted for the 20 dB screening level. In practical terms, if the screener is unable to hear all screening frequencies at 20dB, the screening environment should be reassessed. Of the first 20 children screened, if 2 or more do not pass (i.e. no-pass rate of 10% or higher), the screening environment should be reassessed for excessive ambient noise. |
2. Assemble equipment in desired location. | The audiometer should be on for five minutes (minimum) prior to use. A table and two chairs are required. The student should be positioned to face away from the machine, within view of the screener. The student should not be able to see the examiner's hands or movements. |
3. Check the audiometer: [TICK] Check cords, cushions, and headbands for excessive wearing or cracking. [TICK] Check dials and switches for alignment and ease of movement. [TICK] Listen for the tone through each earphone. [TICK] With the audiometer set for continuous tone, slide the entire length of the cords between the thumb and index finger noting any change in output signal. [TICK] Gently shake the cords. There should be no static, hum, or interruption of the signal. [TICK] Make sure when tone is directed to one earphone, no sound is heard from the other earphone. [TICK] Make sure a steady tone is present at all frequencies. With the tone switch in "normal-off" position, press the interrupter switch several times to make sure the tone is present each time. [TICK] Listen to the frequencies at 20 dB to make sure the tones are audible to the screener with normal hearing. | The audiometer should always be stored with the cords loosely bundled into the box. Wrapping the cords around the head phones damages the wires and will affect the instrument. The audiometer should be professionally serviced and calibrated on an annual basis (minimum). |
4. Give simple but complete instructions to the student: "Listen very carefully. You will hear one tone at a time, sometimes very soft and sometimes louder. When you hear a sound, raise your hand so I can see you have heard that sound, then put your head down and wait for the next sound." | While many students are "trained" to do so, it is not necessary (or significant) for the validity of the screening that the student raises only the hand on the side he or she hears the sound. For the purposes of screening, the student and the screener agree on the reliable signal the student will make indicating he or she has heard a sound. |
5. Place earphones comfortably and securely on the student's head: red earphone on the right, blue on the left. The center of the ear pad should be centered over the opening of the ear. | Push hair behind ears. Make sure headbands or other hair decorations, eyeglasses, and/or earrings are not interfering with the correct placement of the earphones. Head Lice Precautions Use of the audiometer for one student after another may provide a mechanism for physical transport of head lice between students. In school settings where head lice are known to be a concern, the school nurse may consider conducting school wide head checks prior to the screening activity, conducting head checks concurrently with the screening, using a shower cap barrier for each child, and/or having supplies to physically clean (with damp cloth and disinfectant) head phones between children. |
6. Offer a test sound of 40 dB at 4000 Hz to confirm the student demonstrates understanding of the instructions. | Set the tone switch in the "normal-off" position so the tone will sound only when the screener presses the interrupter switch. |
7. Proceed with offering screening tones as follows each delivered separately to the right and left, all at 20 dB, for 2 seconds' duration (say, "hearing test" to yourself). Vary time intervals and sequence between tones. Each tone may be offered up to three times to determine response. Testing frequencies are: 1000 Hz, 2000Hz, 4000 Hz. Pass if the child's responses are judged to be clinically reliable at least 2 out of 3 times at the criterion decibel level at each frequency in each ear. | Work quickly, offer praise. Children with hearing problems may "Pass" due to anticipating patterning by the screener. It is not necessary to continue screening in order to determine the decibel level at which the student does indicate hearing the sound ("threshold screening".) It is sufficient for the purposes of screening to identify whether the student does or does not indicate hearing at desired frequencies at 20 dB. |
8. Record results. | The screening procedure identifies the child apparently not hearing the given frequencies at 20 decibels. Record results by identifying for the Right and Left sides the results for each frequency at 20dB: P (pass) or NP (not passed). For example: R: 1000/P L: 1000/P R: 2000/P L: 2000/NP R: 4000/NP L: 4000/P |
9. Identify the student who should be rescreened, if available, and/or parent notified. | The student who misses any of the frequency tones at 20dB should be rescreened and, if missed tone or tones persist, referred for further evaluation by physician or audiologist. Rescreening should be performed 2-4 weeks following the initial screen. The rescreening validates the initial finding and also allows resolution of transient congestion or inflammation which might temporarily affect hearing - while not allowing excessive delay before further evaluation if indicated. Referrals may be made either to a community medical provider or community audiologist of the parent/guardian's preference, or to the district audiologist. Post treatment screening is indicated to obtain the final outcome of the screening process. |
Additional information and resources are available from the DHHS School Health Program, 402-471- 1373.
173 Neb. Admin. Code, ch. 7, Attachment 2A