Measuring and mapping soundscape speech intelligibility

More than one factor analysis of soundscape perception has concluded that speech communication is a significant contributor to the overall perceived quality of urban soundscapes. While not everything that is perceptually significant in real soundscapes can be quantified it seems likely that speech intelligibility can. There is a large literature on intelligibility focussed on indoor settings. This paper reports on an attempt to use extended speech intelligibility index (ESII) to characterise time-varying speech intelligibility in real outdoor soundscapes. The experiment arose out of the Positive Soundscape Project, a large interdisciplinary project. The relationships between SII, subjective speech intelligibility and subjective speech quality will be explored as functions of signal-to-noise ratio. Using the ESII technique to map soundscapes as one possible sound quality indicator will be demonstrated. Potential implications for the rational planning of soundscapes will be outlined.