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AUDIOLOGY UNIT |
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Last updated 19 February, 2002 |
|
AUDIOLOGY UNIT |
|
Last updated 19 February, 2002 |
PRODUCT NAME: DISTRACTION TEST (ACUTE)
DESCRIPTION: A paediatric behavioural test, routinely applied and nationally accepted as a means of assessing hearing thresholds for patients with developmental age between seven months and 18 months of age. The test is based upon head turn in response to voiced or non-voiced stimuli. Test results can give an indication of hearing thresholds at low, medium and high frequencies on each side. Responses are interpreted and reports completed by an Audiological Scientist.
LOCATION: The test will take place in a large sound-proof room (at least 4m x 4m) with no reflective surfaces and a lighting differential.
PATIENT CATEGORY: Patients with developmental age between seven and 18 months, referred via E.N.T. Medical Staff, Paediatricians and G.P.'s following screen failure or clinical indications/parental concern.
PROTOCOLS: HUMAN RESOURCES: Audiological Scientist (Grade B or above) or well trained Audiologist (Grade 4 or above) plus Audiological Scientist or trained Audiologist (Grade 2 or above).
APPOINTMENT TIME: 80% of patients should be given a first appointment for a date within three weeks of receipt of referral or as indicated by clinical need.
WAITING TIME: 80% of patients attending for this procedure should be seen within 20 minutes of appointment time.
TEST DURATION: 30 minutes.
SET-UP EQUIPMENT: Ready access to sound level meter (S.L.M.), set for free field measurements and calibrated sound-field presentation equipment (e.g. hand-held warblers) and distraction toys.
SET-UP ENVIRONMENT: Upright chair placed in front of low uncluttered table. The view forward and side will be free from excessive distraction.
PATIENT MANAGEMENT:
(1) BRIEFING: Parents/guardians will be informed that the test purpose is to measure the child's ability to hear low, mid and high frequency sounds by presenting sounds to each side and looking for a head or eye turn to a sound.
(2) INVOLVEMENT OF OTHERS: There is a need for one parent/guardian or carer required in the test procedure. If possible, additional relatives, etc., of subjects should not be present, particularly young children.
(3) PATIENT INSTRUCTIONS: The following or equivalent will be given as instructions:
"Please sit on the chair, holding your child on your knees and supported at his/her side, only by your hands. Do not respond yourself, by movement or otherwise, to any sounds that you hear. Please remain silent throughout the test".
(4) PATIENT DEBRIEFING: Brief relevant description of test results obtained in terms of giving an indication of degree of hearing loss consistent with results obtained, with qualification for where reliability may be uncertain and consideration given to results from other tests (e.g. tympanometry).
PRODUCT METHOD:
(1) The tester (distractor) at the front will normally attract the patient's attention with a suitable object (e.g. a spinning toy/man) on the low table. Once this is achieved, the object should be covered by the hands gradually. At the moment, this visual distraction is completely removed from the patient's view, the auditory stimulus will be presented by the rear test worker. The rear tester will present the stimulus in the same horizontal plane as the subject's head, at a distance of approximately one metre. Stimuli will normally be present no further forward than the back of the chair on which the parent is seated. Stimuli will be presented for 10 seconds or until the subject responds by turning, at which time he/she is rewarded with a smile or warbler lights, by the rear tester. The subject's attention is drawn back to the front and the procedure repeated.
(2) Order of Testing: Stimuli will be presented to each side at random, with sufficient blind trials to exclude the possibility of false positive responses.
(3) Criterion of Threshold: Threshold is the lowest sound level at which at least two correct responses (full head turn) out of three stimulus presentations are obtained for each test stimulus/frequency band.
(4) Test Stimuli: Warble tone stimuli, presented from hand held warblers, at 500Hz, 1kHz or 2kHz and 4kHz will normally be used initially. Voiced stimuli (i.e. 'hum' and 'ss') will normally be used if responses, if appropriate, are raised. A high frequency rattle can also be used. The intensity of the stimuli at threshold will be measured during or immediately after the test sequence using a sound level meter.
RESULTS: Thresholds will be entered on a test sheet provided there is clear indication that responses were obtained by the distraction method, threshold levels being measured in 'dB(A)'. An indication of the degree of reliability of results obtained (i.e. due to the behavioural state of the child) will be given.
Interpretation of Results: Individuals interpreting results should be aware that the voiced hum stimulus 'hum' has a frequency spectrum generally centred below 500Hz while the 'ss' stimulus has its frequency spectrum centred around 4kHz. The minimum practical level at which voiced stimuli can be produced is 30dB(A). Due to the free-field presentation of stimuli, hearing thresholds in the worst ear (in cases of marked asymmetry of hearing) may not be readily measured.
REPORTS: Should be produced by an Audiological Scientist (Grade B with CAC qualification or above). Results should be presented, summarised and conclusions drawn with consideration given to results from other tests (e.g. tympanometry).
STANDARDS
LOCAL:
All staff and procedures must conform to the Trusts General Policies and Procedures. These can be found from the Trust Information Server on the local IntrAnet at http://www.cd-tr.wales.nhs.uk/polproc/2000_launch/welcome.htm
Equipment (warblers and S.L.M.'s) calibrated to local specifications of North Wales Medical Physics Department.
STANDARDS
NATIONAL: None.
AUDIT OF QUALITY
INTERNAL: Once, in a six months' period, the length of time patients wait for attention will be monitored and the results recorded and made available for external audit.
An Audiological Scientist (Grade B14 or above) will monitor annually (a) staff performing distraction tests and (b) those analysing results/producing reports. Monitoring will take place while the test is being performed and following report production, to ensure that correct test practices and protocols are being observed by test workers. Monitoring of procedures will be according to local protocols and the results logged and made available for external audit.
AUDIT OF QUALITY
EXTERNAL: