Measurement Challenges in Assessing the Annoying Characteristics of Noise. Is Low Frequency Noise a Special Case?

INTRODUCTION The practice of noise measurement and assessment of its impact upon the individual has, in large part, evolved in parallel with the dominant work technologies and practices of the day. Work practice guidelines emerged in a bid to regulate, relative to health and safety objectives, the impact of exposure to interactions occurring between work technology and work practices, a type of environment. In order to maintain effective assessment criteria and standards it is necessary to take into account the impact of emergent noise forms and environments. An indication that new noise forms and environments have developed will be seen in the diminished capacity of existing noise criteria and practices to account for an increasing instances of apparently anomalous noise annoyance complaints. Measures of noise annoyance will encounter a growing number of cases where the impact of a noise exceeds that predicted. This paper considers how such a gap between noise criteria and emergent noise forms/environments may occur and how noise assessment practices have attempted to reduce this 'gap' through a process of continual adjustment. Moreover, it will consider what it is about the properties of Low Frequency Noise (LFN) that may exacerbate the difficulties associated with making such adjustments. In order to address this general issue it is necessary to examine the type of performance demands that current technologies have contributed towards defining the work place and how assessment criteria have responded. Itwill be argued that effective noise criteria are the product of continued re-examination of what constitutes the key aspects of a given noise/environment interaction. For example, as will be shown, in the areas of hearing impairment, speech intelligibility and transportation noise, new environments have raised new questions regarding the applicability of existing noise criteria. The question here is whether the selected parameters, traditionally measured in order to direct adjustments made to criteria, are equally applicable across spectra and for the type of interaction difficulties associated with LFN. Consequently, it will be argued that a fundamental characteristic of LFN is that of 'intrusiveness' and it is this quality that will provide the basis from which annoyance responses will be experienced within and across a range of work and home environments. Quantifying the range of, and interaction between, variables active within such noise environments has proven to be a continual challenge, but may well represent the most effective method of addressing the interactive and psychophysical basis of noise annoyance.