Acoustic warning signals are necessary to promptly alert workers of events which can compromise safety. Failure to react to warning signals can increase the risk of accidents in the workplace. Unfortunately, the use of warning signals in industry is poorly regulated and submitted to intuitive installation practices, often with little regard to the many factors contributing to an efficient use. This research presents the development of a new software tool called "AlarmLocator" to automate the process of installing auditory warning devices in a given setting, in terms of the characteristics of the devices to use and their optimal location in the plant. The software tool, when use in combination with psychoacoustic model "Detectsound" (Zheng et al., 2006), produces a solution to two practical installation problems: (1) selecting a suitable number of warning devices and acoustic power for a given work area, and (2) specifying the location of the devices in the plant in such a way that the signals emitted are clearly audible by all workers at all workstations. Thus, a solution to the problem of installing warning devices is provided in a format that can be easily understood and used in the workplace. A simple hybrid method, combining the mirror image technique and the classical room acoustics theory was used in this research to compute the sound pressure level generated by acoustic alarm devices. The former technique accounts for wall-placement directivity effects by using a relatively low order of virtual sources to simulate early reverberation. The classical theory of room acoustics is used for late reverberation. The method only requires specification of the overall room dimensions and the estimated or measured reverberation time; however it is currently limited to rectangular-shaped rooms. It was validated in a classroom at the University of Ottawa to verify that sound pressure level predictions by "AlarmLocator" would provide realistic solutions of optimal installation of acoustic warning devices in the workplace. The validation was carried out over 125 arrangements (source, receiver, frequency) and average errors of 0.15 and 2.2 dB were noted for estimated and measured reverberation time conditions. This is well within the design range (13 dB) for the warning sound level window under "Detectsound".
[Work funded by a research grant provided by the Workplace Safety and Insurance Board (Ontario)].
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/27439 |
| Date | January 2007 |
| Creators | Al Osman, Rida |
| Publisher | University of Ottawa (Canada) |
| Source Sets | Université d’Ottawa |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 113 p. |
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