Factors shaping our sound experience: sound, space and listener

Our sound experience is affected by various characteristics of sound sources. The overall sound level is certainly a critical factor. It is also important to consider the characteristics of the sound spectrum. For example, noise annoyance could be increased with more tonal components. Moreover, with a given energy summation, noise annoyance may increase with a larger amplitude fluctuation or emergence of occasional events. Other factors that affect noise annoyance include regularity of events, maximum sound level, rise time, duration of occasional events, spectral distribution of energy, and number and duration of quiet periods. The movements of a sound source, or listener, can change the relative positions of source and receiver, changing all the above factors correspondingly, which, in turn, will change our sound experience. Sounds that are far away, close up or moving in juxtaposition to a listener may provide different information and thus affect the experience. It has been shown that psycho-acoustic qualities differ between stable and passing sounds.

In addition to sound-source characteristics, the acoustic effects of a space are also vital for our sound experience. When sound impinges on a boundary, it may be absorbed partly or totally, or be reflected in one direction or another, and so various sound fields can be formed. Reverberation time, the time for a relatively loud sound to become inaudible in a space, is an important index for the acoustic environment in indoor as well as outdoor spaces, such as streets and squares. It has been demonstrated that, with a constant sound level, noise annoyance is greater with a longer reverberation. On the other hand, a suitable reverberation time, say 1–2 seconds, can make street music more enjoyable. Whereas, in a regularly shaped, fairly reflective enclosure, the sound field may be relatively even, both sound level and reverberation being consistent across the space, there are spaces offering significant changes in sound level and reverberation, so that, when the listener moves, he or she enjoys a varied sound experience. Compared with visual space, aural space is more spherical and all surrounding, with less feeling of boundaries, and it tends to emphasise the space itself, rather than the objects in the space. Sound provides dynamism, helping people to get a sense of the progression of time and the scale of space and encouraging involvement.

On the other hand, it has been demonstrated that correlations between sound evaluation and acoustic factors are often not high, whereas non-acoustic factors relating to listeners play a major role. According to Guski, the noise annoyance to inhabitants depends only on approximately 33 per cent of acoustic parameters such as acoustic energy, number of sound events and length of moments of calm between intermittent noises.1 It is important to consider the sound sensitivity of individuals, as well as the meaning of sounds for them. Moreira and Bryan suggested that those with high noise susceptibility might be persons who show interest in and have sympathy with others, have a great awareness of their environment and are intelligent and creative.² The perception of noise significantly depends on attitude, including fear, cause of noise, sensitivity to noise, activity, perception of the neighbourhood and the global perception of the environment. The effects of various social and demographic factors are also of great importance. For example, the assessment of the sound quality of an urban area depends on how long people have been living there, how they define the area and how much they have been involved in local social life. Expectation is another issue in sound evaluation. In fact, noise regulations are based on an assumption that people expect a different noise environment depending on the quality of the place. Behaviour and habits are important too, including, for example, the opening and closing of windows and the use of balconies or gardens. Season and the time of day may also influence sound evaluation. It has been reported that noise annoyance is greater in summer than in winter, and greater in the evening and at twilight. The idea and experience of an environment are historically conditioned refractions of cultural life. If there were no traffic noise, the soundscape in cities might be filled with church bells, from every direction, day and night. All those factors are related to movement, in terms of time, place and community, for example. On the other hand, people’s attitude could be affected by sounds. For example, it appears that loud noise reduces helping behaviour and induces a lack of sensitivity to others.³

Soundscape on the move: Sheffield Gold Route

For centuries, the development of Sheffield was shaped by waterways. In the recent citycentre regeneration, starting in the 1990s, great efforts were made to ensure that the reconnection with the rivers continued to be fostered, and their role in the history of the city celebrated. Waterscapes and squares were embedded into the city for their vibrancy with respect to the history of Sheffield. Along the Gold Route, as shown in Figure 2.4.1a, a diversity of waterscapes was developed. A series of field questionnaire surveys in selected locations

Figure 2.4.1A The Gold Route in Sheffield, showing the waterscape and the city: (1) Sheaf Square, (2) Howard Street and Hallam Garden, (3) Millennium Galleries and Winter Garden, (4) Millennium Square, (5) Peace Gardens, (6) Town Hall Square and Surrey Street, (7) Barkers Pool Gold Route are shown in Figure 2.4.1b.⁴

Source: Jian Kang