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Biomedical subjects

K J Munro

Publications and source records attributed to K J Munro.

23 records · Page 2Linked to original sources
PubMed1995

Measurement of variability in sound field audiometry due to subject movement.

Sound field audiometry is used primarily for hearing assessment in young children and for functional hearing aid evaluation. It is important that measurements are accurate and reliable as they affect the management of patients. Most clinics use a substitution method for calibration and, as a result, if the subject moves from the calibrated test point, the sound pressure level (SPL) at the ears will vary as the sound field is very rarely uniform. This variation can result in inaccurate threshold estimation and increased test-retest variability. A commonly used method for evaluating the potential errors due to subject movement involves measuring the variation in SPL, with respect to the test point, at six points around the test point. This method makes assumptions about the sound field which may not be valid and could lead to an underestimation of the variation present. The aim of this investigation was to assess the accuracy of this method. Measurements of variation were taken with a microphone and repeated with a head and torso simulator (HATS) which was used to represent a test subject. The total degree of variation indicated by these two methods was compared. The microphone measurements indicated less variation than the HATS measurements. The differences were statistically significant but small in clinical terms. Assuming that the HATS is properly representative of the normal population, then this result indicates that simple microphone measurements are acceptable for normal clinical practice but that higher quality measurements are desirable for critical work.

Audiometry↗
PubMed1995

Difficulties experienced in implementing the ABR travelling wave velocity (Delta V) technique with two commercially available systems.

The ABR Delta V technique involves measuring the difference in latency of the wave V click-evoked ABR in the presence of ipsilateral high-pass noise filtered at 1.42 kHz and at 5.68 kHz. It has been reported that a small latency difference between the two conditions is suggestive of Ménière's disease. The aim of this study was to establish normative data for two commercially available systems. The latency differences obtained in the present study are considerably smaller than those previously reported in the literature. Other problems, including difficulty in identifying wave V in the masked conditions, prevent us from currently using this test technique. There are a number of technical problems which may account for some of the problems experienced when implementing the Delta V technique with commercial equipment and there is at least the possibility that the problems may be overcome in the future.

Adult↗
PubMed1993

Resistance to synthetic pyrethroids in South Australian populations of sheep lice (Bovicola ovis).

Lice were collected from 71 flocks detected as infested at market inspection in 1990 and 1991, from 16 flocks where resistance was suspected and from 31 flocks from Kangaroo Island. Susceptibility to cypermethrin was measured by a treated surface technique and survival of lice at 5 ppm or greater was taken as an indication of resistance. The prevalence of resistance was 34% in louse populations from the market inspection sample, 50% in flocks in which resistance was suspected and 68% in flocks from Kangaroo Island. Most resistance factors were in the range 1 to 20 although one louse population with a resistance factor of 91 was found on Kangaroo Island.

Animals↗