Volume 8

The A, B, C Classification1

The A, B, C System can be traced back to the oldest CSA standard for hearing protectors published in 1965. Subsequent editions of the Standard have kept it with minor changes. However, the Standard is now under revision, expected to be re-issued in the year 2022. It is

unknown if the CSA Technical Committee on Occupational Hearing Conservation that is presently revising the Standard will keep the system or scrap it altogether.

Hearing Protectors

Hearing protectors are the most popular way to control hazardous noise. There are several issues related to the very essence of the protectors and the way they are chosen and used and we will examine some of the basic concepts involved and deal with their practical applications over the next few issues.

Acoustical Materials

It is not unusual for people to “Google” to satisfy their curiosity or learn about something in a “quick and dirty” way. There is nothing wrong there, provided the reader is aware of the limits of the search engines they are using. Such is the case when trying to decide what are acoustical materials?

Reverberation

Reverberation is one of the essential qualities of an auditorium, concert hall, and any other site intended for listening to speech and/or music and is a starting point for the designer of a room or venue.

Volume 7

Do We Really Need an Audiometric Booth?

The “golden rule” for performing an audiometric test requires the use of a booth; however, there are circumstances where booths are absent.

Loudness Perception and Sound Levels

This column points out the difference between the perception of occupational noise and its actual measurement. This is important clinically where we perform a case history. Asking if the client’s work environment is noisy, probably will provide little or no information, especially if they say no.

Annoyance and Low-Frequency Noise

Measurements and assessment of most noises are relatively easy and have commonly accepted standards There are, however, situations, where most of the energy is concentrated in the lower end of the audible spectra, where the assessment presents problems that are not yet solved.

Noise, Vibrations, and Hearing Loss in the Workplace

This is a review of papers accessed from the Google ScholarTM and MendeleyTM databases that deal with risk of hearing loss when mechanical vibrations are also applied to the bodies of noise-exposed workers.

The Ubiquitous (or Mysterious Decibel (dB)

Noise expert Alberto Behar explains why the dB is not a unit at all.

Those Annoying Low-Frequency Noises…

Alberto Behar explores the issue of low-frequency noise.