A literature review was conducted as part of this study to gain relevant knowledge from prior experiences. The volume of research and knowledge in the field of acoustics is quite staggering. However, the links between sound, noise and their effect on pe ople and communities are still far from being concretely resolved. There is even less literature available on the connection between helicopter noise and human response. Thus, this research sheds some light on the complex problem of noise and human perc eption and reaction, by focusing on the interaction between helicopter operations and rural residents in the Hawaiian islands.
Day-night average noise level equivalents such as Ldn tend to 'railroad' isolated and infrequent noise events of considerable intensity and duration. Ldn fails to represent community reaction adequately when noise events are infrequent. Helicopters gene rate a distinct noise which is a mixture of noise from many sources: Engine, aerodynamics, main rotor, tail rotor and interaction of the vortices created by the two rotors. Blade slap is typically annoying, but it is not present in several maneuve rs, speeds and rotor configurations.
Annoyance is the major attribute of noise which generates negative response from communities. The level of annoyance can be assessed through laboratory or field experiments, and through attitudinal surveys (as in this project) or interviews. There is li ttle scientific evidence with respect to the connections between actual noise measurements and perceived (i.e., revealed through survey or interview) annoyance. Much more research is needed in this area.
The backbone of the analysis consists of three distinct sequential steps: (1) analysis of variance which permits a thorough investigation of the association of independent variables on a given dependent variable; (2) factor analysis which he
lps to combine several related variables into one composite variable. Factor analysis was used to estimate the overall attitude of respondents towards helicopters and the combined attitude towards development, growth and tourism. (3) Model estimation. The answer to most of the questions that we needed to answer were binary in nature (e.g., helicopter flights are or are not annoying). For this reason, logistic regression models were estimated. The following answers are the result of our analyses
The degree of exposure and the residential location are two of the most important factors related to the issue of helicopter noise. An annoyance problem does exist but it is geographically narrow (e.g., along broad corridors connecting airports with sigh
tseeing destinations). Most respondents agree on the positive impacts of tour helicopters on the local economy and in emergency situations. It is also clear that DEA flights cause major disturbance and feeling of invasion of privacy. Reduction of expos
ure to helicopter noise, clear distinction between DEA and tour operations and some form of government regulation are the likely ingredients of the solution to the problem.
Results from this study are in Transportation Research Record 1444, 1475 and 1559.