Evaluation of Hearing In Neonates and Infants H. C. TANEJA, Senior Resident Deptt. of Neurosurgery, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow. M. SINGH, Asstt. Prof. K. K. LAL, Asstt. Prof. (Audiology & Speech Pathology), A. P. SINGH, Prof. & Head S. KUMAR, Audiometerician, RAMA MISRA, Professor, Deptt. of Otorhinolaryngology, Head & Neck Surgery, M.L.N. Medical College, Allahabad Hearing evaluation of sixtyfour neonates andinfants selectedrandomly from the outpatient departments of E. N. T., Paediatrics and Obstetrics wards was done by behavioral observation audiometry (BOA), tympanometry, acoustic reflex andauditory brainstem evoked response audiometry(ABR) in selected cases. A good correlation was found between BOA and ABR. Tympanometry and acoustic reflex measurements were not found to be useful for evaluating hearing status in infants and neonates. It was finally recommended that BOA should be used for screening hearing in infants and neonates. Cases who fail in BOA should be subjected to ABR for establishing true threshold of hearing. INTRODUCTION T he human infant acquires speech through the process of learning by listening to others. Impaired hearing, therefore, leads to mutism. For preventing mutism, identification and proper rehabilitation at an early age is mandatory. A number of methods for evaluation of hearing in newborn and infants have been developed namely behavioral observation audiometry', respiratory responses", cardiac responses", crib movement systemt', non-nutritive sucking response audiometry', impedance audiometry 1 °, auditory brainstem evoked response audiometry' and more recently evoked otoacoustic emissionss. In the present study behavioral observation audiometry, impedance audiometr y and auditory brainstem evoked response audiometry were used for evaluation of hearing in newborn and infants. MATERIAL & METHODS Sixtyfour neonates and infants were selected randomly from the Department of Paediatrics, Obstetrics wards and from the ENT OPD who came for suspected hearing loss. A detailed prenatal,natal and postnatal history including developmental milestones were taken. A thorough general and ENT examination was done. Hearing evaluation was done in each case by BOA, Tympanometry and acoustic reflex. ABR was done in selected cases. For BOA we used hand held type Paediatric pure tone audiometer model Arphi AP-II. This apparatus delivers puretones of 500 Hz, 1000 Hz, 2000 Hz and 4000 Hz. At 50 cms. distance from the test ear this audiometer can deliver tones at 30 dB, 50 dB, 70 dB and 90 dB intensities. Reduction of distance to 16 cms. gives increment of 10 dB. Test was usually carried out 45 minutes to one hour prior to next feed in a sound treated room. Infant was placed comfortably on couch or in attendants lap. Preferably test was performed when infant was asleep. When infant was awake the examiner stood behind the head of the infant. Before starting the test infant's state was observed for a few moments. Test tone was delivered for a few seconds at 90 dB intensity by placing the paediatric audiometer at a distance of 50 cms. From the test ear and response was observed in the form of auropalpebral reflex. If infant failed to respond at 90 dB then intensity was increased to 100 dB by reducing the distance of audiometer to 16 cms. from infant's test ear. Tests were conducted at an interval of 15 seconds. Before declaring no response at 100 dB (maximum output of the audiometer) infant was tested 3-6 times. Responses were noted for 500 Hz, 1000 Hz, 2000 Hz and 4000 Hz frequencies. The other ear was tested similarly. For tympanometry and acoustic reflex, we used American Electromedics Tympanometer (Automatic) model 86 AR. For carrying out tympanometry 220 Hz probe tone was used, ipsilateral acoustic reflex was also recorded automatically by presenting a tone of 1000 Hz at 105 dB. This test was performed when infantwas asleep. Infant was kept in attendant's lap. Pinna was pulled outwards to straighten the canal. Appropriate size probe tip was fitted in No! 46, ; No 4, Oct -Dpc 1994 lJO & HNS • ?R'