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Highlights • Acoustical and visual characteristics are both associated with noise annoyance. • Wind turbine visibility increases noise annoyance. • Serial position effects modify audio-visual effects on annoyance. • Presentation order of audio-visual simulations should be considered carefully. Abstract Noise annoyance reactions in the population due to wind farms are related to visual as well as noise-related impacts of the farms. Improved understanding of these effects may support the planning of better accepted wind farms. Recently, tools for visualization and auralization of wind farms have been developed that allow mutually studying audio-visual effects on annoyance. The objective of this study was to investigate the audio-visual effects of different wind turbine noise situations on short-term noise annoyance in a psychophysical laboratory experiment, considering serial position effects (simple order and differential carryover effects). A set of 24 audio-visual situations covering a range of acoustical characteristics (sound pressure level, periodic amplitude modulation) and visual settings (landscape with visible wind turbine, landscape only, grey background) was created. The factorial design of the experiment allowed separating audio-visual effects from serial position effects on noise annoyance. Both visual and acoustical characteristics were found to affect noise annoyance, besides the participants' attitude towards wind farms. Sound pressure level and amplitude modulation increased annoyance, the presence of a visualized landscape decreased annoyance, and the visibility of a wind turbine increased annoyance. While simple order effects could be eliminated by counterbalancing, the initial visual setting strongly affected the annoyance ratings of the subsequent settings. Due to this differential carryover effect, visual effects could be assessed reliably only as long as the participants saw the initial visual setting. Therefore, the presentation order of audio-visual stimuli should be carefully considered in experimental studies and in participatory landscape planning. [ABSTRACT FROM AUTHOR]

• A semantic differential was developed for environmental broadband sounds, including wind turbines. • The semantic differential uses affective-evaluative everyday language to describe sounds. • The underlying perceptual dimensions were used in an annoyance prediction model. • The results can be applied in a perception-influenced design approach for sound optimization. • The semantic differential may be used in field surveys for multi-facet perceptual assessments. Growing numbers of the population are exposed to wind turbine (WT) and other broadband sound sources from the environment. Acoustically optimizing emissions of environmental noise sources to minimize negative effects on the population therefore becomes increasingly important. The objective of this study was to develop and apply a semantic differential (SD) for multidimensional perception-based assessment of WT and other broadband sounds, to be potentially applied for acoustic optimization. An SD was developed specifically for broadband sounds and applied in a laboratory listening experiment, using outdoor WT and other broadband sounds covering a wide spectral range, at 40 dBA playback level. Fifty-two participants rated the sounds using the SD. Relevant perceptual dimensions were extracted, and a prediction model for noise annoyance was established on this basis. The experiment revealed that participants could well describe and discriminate the sound characteristics using the affective-evaluative everyday language of the SD. Four perceptual dimensions (or factors) were identified: Evaluation , Timbre , Activity and Randomness , with the latter three describing spectral shape, periodic amplitude modulation and random amplitude modulation, respectively. The factors were strongly linked with annoyance and well suited to establish an annoyance prediction model. The results can be applied in a perception-influenced design to identify how to optimize (perceived) acoustical characteristics and thus minimize annoyance effects on the population. Also, they might potentially be used in field surveys for a multidimensional assessment of broadband sounds to study the long-term annoyance potential of specific perceptual characteristics. This might eventually help to refine exposure–response relationships using predictors beyond basic noise metrics. [ABSTRACT FROM AUTHOR]

Residents of densely populated urban areas are often exposed to high road traffic noise. While noise control measures help mitigating road traffic noise exposure in residential areas (e.g., inner courtyards), their psychoacoustic impacts on residents have not been well explored. In this study, effects of façade surface material (sound reflecting, absorbing or diffusing) and building rotation (parallel vs. nonparallel walls) on perceived noise annoyance were investigated in laboratory experiments. To that aim, a virtual acoustic environment within a residential area was designed. Moving passenger cars were artificially generated by convolving synthesised car emission sound signals with position-specific impulse responses and simulating sound propagation for static receiver locations along different vehicle trajectories. A method to interpolate the impulse responses was developed to generate receiver audio signals of a continuously passing vehicle. The resulting stimuli were spatially reproduced using loudspeakers. The laboratory experiments revealed that absorbing façades were associated with lower noise annoyance than reflecting or diffusing façades due to reduced sound pressure level. However, at the same level, the absorbing façades were perceived as more annoying than the reflecting or diffusing façades, indicating somewhat unfavourable acoustical quality. Building rotation (resulting in nonparallel walls) was associated with lower noise annoyance compared to the original parallel-wall building orientation. While this was due to reduced sound level as well, the positive effect also tended to remain when the level was the same for rotated and parallel buildings. Our experiments show that façade characteristics and building orientation may be important architectural features to optimize the sound environment of inner courtyards. • Auralisation of a moving car in an urban area with a new method based on synthesized emission. • Listening tests on the effect of different façades materialisation. • Listening tests on the effect of slightly rotated buildings. • Sound-absorbing façades reduce noise annoyance compared to reflecting ones. • Slight rotation of initially parallel façades reduces noise annoyance. [ABSTRACT FROM AUTHOR]

• Residential green reduces road traffic and railway noise annoyance. • The annoyance reduction is equivalent to 6 dB (road) and 3 dB (rail). • Residential green is associated with increased aircraft noise annoyance. • The annoyance increase is equivalent to 10 dB (air). • Quality attributes of residential green depend on the degree of urbanization. In recent years, residential green and availability of neighbourhood green spaces came into focus as a potential means to reduce transportation noise annoyance. Literature suggests that various characteristics of residential green may play a role, namely, greenness of the residential areas as quantified by the normalized difference vegetation index (NDVI), visible vegetation from home, and the presence of public green spaces as identified by land use classification data (LU-green), as well as their accessibility and noise pollution (i.e., transportation noise exposure within green areas, how loud/quiet they are). So far, studies mostly focused on road traffic noise in urban areas. We investigated the effects of residential green on noise annoyance, accounting for different transportation noise sources as well as for the degree of urbanisation. We complemented the data set of the recent Swiss SiRENE survey on road traffic, railway and aircraft noise annoyance with a wide range of "green" metrics, and investigated their association with annoyance by means of logistic regression analysis (generalized estimating equations). Increasing residential green was found to be associated with reduced road traffic and railway noise annoyance, but increased aircraft noise annoyance. The overall effect corresponded to equivalent level reductions of about 6 dB for road traffic and 3 dB for railway noise, but to an increase of about 10 dB for aircraft noise, when residential green increased from "not much green" (5th percentile of the study sample distribution) to "a lot of green" (95th percentile). Overall, NDVI and LU-green were particularly strongly linked to annoyance. The effects of visible vegetation from home and accessibility and/or quietness of green spaces were, overall, less strong, but depended on the degree of urbanisation. For road traffic noise, visible vegetation and accessibility of green spaces seem to particularly strongly reduce annoyance in cities, while quiet green spaces are more effective in rural areas. Our study emphasizes that residential green should be fostered by city planners, particularly in densely populated areas. [ABSTRACT FROM AUTHOR]

New aircraft concepts are currently being developed with the goal of less emissions of CO 2 and noise. Remarkable noise reductions in long-range aircraft can only be expected from disruptive vehicle designs, new propulsion systems and specific low-noise technologies. In this paper, one such future vehicle design, a blended wing body (BWB) long-range aircraft, is described and studied with respect to sound levels on the ground, sound characteristics and noise annoyance. Virtual flyovers of different vehicle variants were synthesized and auralized in an acoustic VR environment, and investigated through psychoacoustic laboratory experiments. The applied methodology was successfully hierarchically validated by comparison with measurements of existing jet aircraft, assessing acoustical indices, time-frequency features, perceived plausibility, and induced noise annoyance. The perception-based evaluation of the BWB revealed that, while the BWB aircraft may initially be perceived as somewhat more unfamiliar, they are substantially less annoying than current tube-and-wing long-range aircraft of similar range and mission for take-offs as well as for landings. For the best BWB variant, noise annoyance was reduced by 4.3 units for departures and by 3.5 units for approaches on the 11-point scale. The main reason for these findings seems to be the acoustic shielding by the body of the extended fuselage, which was found to be an important factor in reducing sound levels in the order of 10–20 dB, and accordingly also to strongly reduce loudness. Additional low noise technologies and geared turbofan engines with a high bypass ratio further contributed to the reduction of noise annoyance of the BWB. A large part of the BWBs benefit could be explained by its lower sound levels, but additional benefits were found. The observed reduction in noise annoyance was found to be larger than what can be explained with conventional noise metrics. This benefit is probably due to more favorable sound characteristics compared to today's reference aircraft, such as less variation in time and less audible tones. The current study thus suggests that the studied BWB vehicle concept may substantially reduce noise annoyance on humans. [ABSTRACT FROM AUTHOR]