Subjective Preferences for Birdsong and Insect Song in Equal Sound Pressure Level

Abstract

Birdsong is used as a sound signal for visually impaired people in train stations in Japan. However, such sound signals were reportedly difficult to be localized by over 40% of visually impaired people. More than 40% of visually impaired people reported that such sound signals were difficult to identify. The sound pressure level of birdsong is typically low because higher levels of birdsong can cause annoyance to users or residents. Therefore, preferences for birdsong should be investigated. Importantly, birdsong and insect song have been shown to have a positive effect on soundscapes. However, preferences for different types of birdsong and insect song have not been investigated. The current study sought to clarify which types of birdsong and insect song are preferred, and to determine the dominant physical parameters that relate to the preference. We evaluated subjective preferences for various types of birdsong and insect song using paired comparison tests. The relationships between subjective preference and physical parameters were examined. The results indicated that Horornis diphone and Teleogryllus emma were the most preferred types of birdsong and insect song, both of which are common in Japan. The maximum peak amplitude of the autocorrelation function, determinants of which are pitch salience, loudness, and spectral content, such as centroid, flux, and rolloff, are significant parameters influencing subjective preference.