Enquiry into the effects of loud sounds upon the hearing of boilermakers and others who work amid noisy surroundings / by Thomas Barr.

  • Barr, Thomas, 1846-1916.
Date:
[1886]
Catalogue details

Licence: Public Domain Mark

Credit: Enquiry into the effects of loud sounds upon the hearing of boilermakers and others who work amid noisy surroundings / by Thomas Barr. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    In order to draw a comparison between the hearing of these men and that of some other classes of the community, I have examined also 100 ironmoulders and 100 letter-carriers with reference to their powers of hearing. Through the kindness of Mr. Campbell of the Hyde Park Foundry, and of Mr. Dawson of the General Post Office, I have been enabled to carry out these examinations. The ironmoulders are not especially exposed to very loud sounds, but their ears are menaced from another direction—namely, through the nasal passages. The middle ear which is the seat of most of the diseases of the ear, is really an offshoot from the nasal passage, the lining of which, in ironmoulders must almost constantly be coated with irritating dust and dirt. Besides, their exposure to great extremes of temperature must, by exciting nasal catarrhs, still further contribute to an unhealthy state of their nasal mucous membrane. Such an unhealthy state is very ready to invade the middle ear. We would therefore expect a small sum total of hearing for iron- moulders. Letter-carriers, on >the other hand, from the com- paratively healthy nature of their employment, enjoying, as they do, so much of the fresh open air, may be looked upon as living under circumstances pretty favourable to a healthy state of the organ of hearing. The following numbers give the results of the application of the hearing test with the watch to these 300 letter- carriers, ironmoulders, and boilermakers, including 600 ears :— Total number of inches at which the tick of a watch should be heard by 100 Men having normal hearing, 7,200. 100 Letter-earners (average age 30yrs.) heard 5,094 or 79% of normal hearing. 100 Ironmoulders ( „ 374 „) heard 3,291 „ 45f% 100 Boilermakers ( „ 35 ,, ) heard 704,, 9J°/o » >> 2. The power of hearing speech:— In addition to the watch I also tested the hearing of these 100 boilermakers, with the voice. It is important, in order to form an accurate notion of the state of the hearing, not to limit oneself to such a test as the tick of a watch, or other such simple mechanical sound. There is not unfrequently in deafness a strange disparity between the power of hearing a watch and the power of hearing the voice. We meet with persons who hear the watch very badly, perhaps no farther off than an inch from either ear, and yet they hear quiet conversation so well, that their friends do not observe any defect of the hearing. We meet with others, on the contrary, who hear the watch as far as 20 inches