Sample-based engine noise synthesis using an enhanced pitch-synchronous overlap-and-add method

Research on the characteristics of EV interior sound quality and its dynamic active control system design and development un-der accelerated driving conditions

In order to improve the interior sound quality of Electric Vehicles (EV), solve the problem of low sense of power and comfort of the interior sound as well as the large electromagnetic excitation order noise of motor and the sharp interior sound, this article designs a dynamic active sound control system for EV under accelerated driving conditions. Firstly, by comparing and analyzing the sound spectrum characteristics of fuel vehicle (FV) and EV during acceleration, a short-time Fourier transform (STFT) is adopted to extract and synthesize the engine sound. Secondly, the influence of the engine order composition and the energy distribution in the frequency domain on the sound quality of the vehicle is analyzed, and an active control system for sound quality is proposed. And the software and hardware development of the active control sound system is completed. Finally, through real-vehicle testing and verification, the sense of comfort and power of the EV interior sound has been greatly improved during acceleration, and the total value of interior sound can meet the requirement. The sound pressure level and loudness of interior sound have been increased, and the sharpness of the sound inside the vehicle has been improved, with a maximum reduction of 1.0acum.

Synthesis of wind turbine trailing edge noise in free field

The proposed sound synthesis tool converts a physics-based frequency-domain model of wind turbine trailing edge noise to a time-domain signal while accounting for the appropriate time shift due to the propagation between the moving blades and the fixed observer. A window function that implements cross-fading between consecutive signal grains is proposed and a method to objectively estimate the influence of the synthesis parameters is described. As the synthesis tool is independent of the aerodynamic noise model, it can be readily adapted to auralize other noise sources such as turbulent inflow noise or stall noise.

Urban Sound Auralization and Visualization Framework—Case Study at IHTApark

In the context of acoustic urban planning, the use of noise mappings is a worldwide well-established practice. Therefore, the noise levels in an urban environment are calculated based on models of the sound sources, models of the physical sound propagation effects and the position of the receivers in the area of interest. However, the noise mapping method is limited to sound levels in frequency bands due to missing temporal and spectral information of the sound signals. This, in turn, leads to missing information about the qualitative sound properties, as they can be evaluated in psychoacoustic parameters. Beyond the scope of the classical noise mapping, auralization and physically-based simulation of sound fields can be applied to urban scenarios in the context of urban soundscape analysis. By supporting the auralization technology with a visual counterpart of the urban space, a plausible virtual representation of a real environment can be achieved. The presented framework combines the possibilities of the open-source auralization tool Virtual Acoustics with 3D visualization. In order to enable studies with natural human response or for public communication of urban design projects, those virtual scenes can be either reproduced with immersive technologies—such head-mounted displays (HMD)—or using online video platforms and traditional playback devices. The paper presents an overview of what physical principles can already be simulated, which technological considerations need to be taken into account, and how to set up such environment for auralization and visualization of urban scenes. We present the framework by the case study of IHTApark.

Improving future low-noise aircraft technologies using experimental perception-based evaluation of synthetic flyovers

Residents living in the vicinity of airports are exposed to noise from departing and approaching aircraft. Noise may be reduced by introducing novel aircraft technologies into vehicle retrofit, aircraft design and flight procedures. Nowadays, noise assessment and communication of noise are accomplished using conventional noise indicators that consider neither the perception of sound, nor its health effects. To overcome these limitations, this article presents a more comprehensive approach that supports the movement for perception-influenced design in order to reduce the negative environmental impacts and adverse health effects caused by increased air traffic noise. By means of auralization (the acoustical counterpart of visualization), possible future changes can be evaluated by considering the human perception of sound. In this study, in a virtual acoustic environment flyovers of different aircraft types and flight procedures are auralized for ground-based receiver locations, and subsequently evaluated in a psychoacoustic laboratory experiment with respect to short-term noise annoyance. Flight approaches of an existing reference aircraft, a possible low-noise retrofitted vehicle and a future low-noise vehicle design were simulated along standard and tailored flight procedures. To create realistic listening experiences of synthetic flyovers, auralization technologies were further developed regarding source synthesis, transitions between aircraft conditions, sound propagation effects and immersive sound reproduction. Listening experiments revealed significant annoyance reductions for low-noise aircraft types and tailored flight procedures, and that maximum benefit is achieved by the combined optimization of aircraft design and flight procedure. Further, it is shown that spatially distributed receivers need to be considered for a reliable low-noise aircraft technology evaluation. The reduction potential in terms of perceived noise by retrofitting current vehicles and designing new vehicle architectures is thus demonstrated. These findings suggest applying the proposed comprehensive approach to effectively reduce the impact of perceived air traffic noise in the future.