The potential effects of noise disturbance

Noise may be defined as a sound which is undesired by the recipient and therefore the perception of a sound is of crucial importance in assessing potential 'noise nuisance'. The subjective nature of noise makes it one of the most difficult of all environmental impacts to quantify. The problem of noise nuisance assessment is compounded by the difference in perception of noise between participants and non-participants and also between participants in the same activity.

Certain types of water-based recreation, such as personal watercraft activities, are considered to cause noise nuisance whether recorded sound levels of the activity are high or low relative to other sound sources. This is often because the 'quality', or tonal note, of a sound is more important to the listener’s perception of that sound than its magnitude. However, this is an entirely subjective concept and is therefore unmeasurable. This creates problems with the assessment of whether a particular sound constitutes a noise nuisance.

Sound generated by recreational craft originate from a number of different sources including:

• craft hull striking or ploughing through waves (hull slap)
• boat generated waves striking the shore
• mechanical noise (from engines)
• deck and cabin fittings, people noise (human propulsion or interaction on board)

Noise disturbance relates largely to impacts upon other people rather than impacts upon the natural environment. Such issues lie outside the scope of this study. However, the potential impacts of noise disturbance on sublittoral and other marine communities are not known. In addition, disturbance to seals and dolphins and other wildlife is attributable to sound as well as to physical proximity and this is discussed below in more detail. Many representative and industry bodies produce codes of practice which address the issue of noise disturbance.

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