Soundscape Assessment of Aircraft Height and Size

Abstract

It is accepted knowledge that, for a given equivalent sound pressure level, sounds produced by planes are worse received from local communities than other sources related to transportation. Very little is known on the reasons for this special status, including any interactions that non-acoustical factors may have in listener assessments. Here we focus on one of such factors, the multisensory aspect of aircraft events. We propose a method to assess the visual impact of perceived aircraft height and size, beyond the objective increase in sound pressure level for a plane flying lower than another. We utilize a soundscape approach, based on acoustical indicators (dBs, LA, max, background sound pressure level) and social surveys: a combination of postal questionnaires (related to long-term exposure) and field interviews (related to the contextual perception), complementing well-established questions with others designed to capture new multisensory relationships. For the first time, we report how the perceived visual height of airplanes can be established using a combination of visual size, airplane size, reading distance, and airplane distance. Visual and acoustic assessments are complemented and contextualized by additional questions probing the subjective, objective, and descriptive assessments made by observers as well as how changes in airplane height over time may have influenced these perceptions. The flexibility of the proposed method allows a comparison of how participant reporting can vary across live viewing and memory recall conditions, allowing an examination of listeners' acoustic memory and expectations. The compresence of different assessment methods allows a comparison between the “objective” and the “perceptual” sphere and helps underscore the multisensory nature of observers' perceptual and emotive evaluations. In this study, we discuss pro and cons of our method, as assessed during a community survey conducted in the summer 2017 around Gatwick airport, and compare the different assessments of the community perception.

Sound localization in web-based 3D environments

“…Further analysis of the data showed that almost 16% of the participants did not perceive the sound had an elevation: they placed it at the correct azimuth , but with . This difficulty in the vertical axis (elevation) was also observed in experiments correlating the perceived height of planes with their perceived noise 40 . In those experiments, observers tended to make a wrong assessment of the altitude of passing aircraft and thus alter their acoustic judgment.…”

“…In those experiments, observers tended to make a wrong assessment of the altitude of passing aircraft and thus alter their acoustic judgment. Further studies on this uncertainty in position sources in elevation may help to explain the large variability of annoyance statements due to aircraft noise in comparison to what is reported with other transportation sources for the same acoustic level 40 , 41 .…”

Spatial Soundscapes and Virtual Worlds: Challenges and Opportunities

“…Table 1 also highlights how the sound sources positioned along azimuth angles are easier to localize than sources at different elevations. This is crucial for 3D soundscape designers (Hruby, 2019 ) and for interpreting data in a cityscape (Memoli et al, 2018 ).…”

“…It is very challenging to estimate the distance of a source, such as the altitude of an overflying plane, and this results in large errors in real life (Memoli et al, 2018 ). Localization improves when a user is allowed to move towards the source, which is crucial for audio-only AR environments (e.g., a voice describing places).…”

“…There is often a correlation between the acoustic and visual judgments of a soundscape (Watts et al, 2011 ; Memoli et al, 2018 ; Ahrens et al, 2019 ). Since in VR the balance may be altered, e.g., by presenting visual and acoustic stimuli at different times, it is, therefore, important to quantify their relative weights.…”