Bryan Lawton

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At frequencies greater than 2 kHz the acoustic impedance at the human eardrum is an unreliable indicator of the behavior of the middle ear system because of the complicated configuration of the ear canal and tympanic membrane. The energy reflectance at the eardrum, however, when obtained from measurement of the standing wave ratio (SWR) in the canal, is(More)
The geometry of 15 human ear canals has been studied. Silicone rubber molds were made of the ear canals of human cadavers, and a mechanical probe system was used to obtain approximately 1000 coordinate points over the surface of each mold. The data points were accurate to about 0.03 mm in each of the three space directions, allowing ample resolution of(More)
This paper questions the necessity for two calibration devices to measure the acoustic output from different types of audiometric earphones. International standards give the audiometric zero for TDH39 earphones on the IEC 60318-3 acoustic coupler; the IEC 60318-1 ear simulator is intended for other supra-aural earphone types. If hearing threshold samples(More)
Standing wave patterns were measured in the unoccluded ear canals of 13 human subjects, for applied pure tones of 3 to 13 kHz. Measurements were made, using a probe microphone technique, over a region which could be approximated as a duct of constant cross-sectional area. Analysis of the patterns allowed the reflective properties of the middle ear to be(More)
OBJECTIVES The objective of this study was to review critically a number of occupational investigations of the exposure and effect relation between inhaled styrene vapour and hearing loss. There is concern that workers' hearing may be impaired by exposure to styrene, as used in industries making plastics and fibreglass-reinforced products. METHODS Seven(More)
The HERschel Inventory of The Agents of Galaxy Evolution (HERITAGE) of the Magellanic Clouds will use dust emission to investigate the life cycle of matter in both the Large and Small Magellanic Clouds (LMC and SMC). Using the Herschel Space Observatory’s PACS and SPIRE photometry cameras, we imaged a 2◦ × 8◦ strip through the LMC, at a position angle of(More)
Medicolegal assessment in relation to a claim for hearing damage requires an equitable baseline against which to compare the state of hearing of the claimant. This baseline, or 'notional person', should match the claimant in every respect save for the cause of the hearing loss. The amount of compensation is determined from the difference between the(More)
Accurate computation of gun barrel temperature history is necessary to predict the barrel-wear and cook-off. Most of the previous researchers, in their computational models, neglected the variation of thermal conductivity and specific heat of gun metal, with temperature. It is expected to introduce an error in the results. In this work, this error was(More)