Appendix 2: Childhood hearing screening after the neonatal period – procedure
Pure tone screening audiometry
Recommended screening level at preschool age (3-5 years) is 25 dB -35 dB HL, depending on the pre-established target condition. Hearing levels are in decibel, dB. The screening frequencies are 1000, 2000, 4000, 6000 and 500 Hz. The minimum requirements are for frequencies 1000 Hz, 2000 Hz and 4000 Hz. 6000 Hz is not always included at this age. 500 Hz may be screened at a level 5 dB higher than the other frequencies if the target condition does not include temporary hearing impairment (otitis media). 500 Hz may be excluded from the test sequence if necessary. For school age children (6-7 years), the recommended screening level is 20-30 dB up to 6000 Hz, also depending on the pre-established target condition. The available capacity for diagnostic assessment may play a role in determining the screening level, since a lower level means more referrals and therefore a need for more diagnostic assessments.
- Check the equipment: before testing for the day, the tester should test the equipment to make sure the sounds are at the right volume for each frequency. The tester should listen to each frequency that will be tested at 40 dB HL. If the tones are not at the correct level, then the equipment should be inspected to make sure all connections are in place and the settings are correct.
- Preparation: pure tone audiometry is a behavioural test that requires cooperation and participation from the child. It is important that the child is well rested and fully focused during the screening.
- Instruction: Prior to performing the hearing test, the child should learn the task and show that they understand the instructions.
- Sound stimuli: pure tone audiometry is performed with headphones. The sound is a pure tone sine wave. Warble tones may be used in younger children for better attention.
- Headphones: Put the headphones (TDH39) on the child’s head. It´s important that they are comfortable and well placed covering the opening of the ear canal.
- Test protocol: Start with the right ear or the best ear if there is a suspected HI in one ear. Start with frequency 1000 Hz at a well audible level, 40 dB. Give the child instructions and check that they are well understood.
- Response from child: in response to a sound the child should be instructed to perform some kind of action. Pushing a button does not work well with small children and instead they can build with blocks, put a ring on a peg, or raise their hand.
- If the child cannot hear 40 dB, increase with 10 dB stepwise until the child gives a response. Increase to maximum 60 dB (this is a screening situation). Check that the child understands the instruction. If there is no response to 60 dB, try other frequencies or the other ear.
- If the child responds to 40 dB, change to screening level 25 dB (30 dB). Present the stimulus twice with a duration of 1-2 seconds at an interval of 3-5 seconds. If the child responds to both stimuli there is a pass. Continue and test the next frequency in the same way: 2000 Hz at 25 dB, 25 dB HL 4000 Hz, 25 dB HL 6000 Hz, 25 dB HL 500 Hz.
- If the child can only hear one stimulus, present a third tone. If the child can hear it, the screening is passed for the first frequency.
- If the child cannot hear the third tone, the child has not passed.
- Continue with other frequencies and the other ear.
- Referral criteria: No pass at 2 frequencies 500 – 4000 Hz in the same ear or >40 dB at 1 frequency 1000- 6000 Hz.
- Retest: the screening result must be evaluated according to cooperation of the child or health status that may affect the ears. If the child fails the hearing screening, a retest should be performed frequently before referral.
Same procedure as above, but with a play activity in response to sound instead of pushing a button. Prior to the test, the tester should prepare a few activities for the child to use to indicate a response. If one activity is not interesting to the child, another activity can be suggested.
Inconclusive test results
Normal speech development indicates normal or near-normal hearing. However, a child with a refer result from hearing screening, despite normal speech and no obvious hearing problems, should always be referred for further evaluation.