Generating Sequences of Acoustic Scintillations

Rietdijk, Frederik; Forssén, Jens; Heutschi, Kurt

doi:10.3813/aaa.919061

Cited by 18 publications

(13 citation statements)

References 12 publications

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“…Further research is needed to fully quantify the change in measured noise intensity caused by wind-gusts and develop a methodology to introduce them with the required intensity into the synthesis process. Some work in this regard is being carried out by other organizations such as in [25]. It would also be beneficial for future comparisons to limit the effect of wind-gusts by either choosing a calmer day (average wind speeds on the day of the measurement were around 3 m/s), adding wind-screens around the microphone or reducing the height of the microphone from its current position at 10 m altitude.…”

Section: 2mentioning

confidence: 99%

Objective quantification of perceived differences between measured and synthesized aircraft sounds

Sahai

Snellen

Simons

2018

Aerospace Science and Technology

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This paper presents an approach with which perceived audible differences in aircraft sounds can be quantified and presented in an objective manner. The objective quantification of the subjectively heard audible differences is intended to serve two primary goals. It can firstly enable developers of auralization technology to make the auralized sounds more realistic by identifying in which aspects the synthesized sounds differ from their real-life counterparts and to what extent. The quantification can secondly provide an improved and more detailed means of distinguishing between aircraft sounds in general, beyond the conventional metrics of A-weighted Sound Pressure level (dBA) or Effective Perceived Noise Level (EPNL) used currently to assess aircraft noise. In this study sound quality metrics are used to quantify the differences in aircraft sounds. These metrics are widely used in other industries such as the automotive sector. Audio files of a reference aircraft, made over identical flight paths at a noise monitoring station in the vicinity of Schiphol airport, are compared in terms of both conventional and sound quality metrics for four measured and four auralized audio files. It is observed from the comparison that differences that may appear small in the conventional metrics can be significant in terms of the sound quality metrics. Significant differences in measured and synthesized sounds are observed for the aircraft considered in this study with regards to the tonal content and fluctuations in amplitude that occur over time. The conventional metrics are seen to capture the overall loudness aspect of aircraft sounds, but give no clear information regarding which spectral or temporal characteristics cause the sounds to be perceived as audibly different.

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Section: 2mentioning

confidence: 99%

Objective quantification of perceived differences between measured and synthesized aircraft sounds

Sahai

Snellen

Simons

2018

Aerospace Science and Technology

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“…Hence, turbulence does not affect the resulting sound paths. It can be included during the auralization process using time-variant filters [15]. Furthermore, a common simplification for the atmosphere is the so-called stratified medium [7].…”

Section: Stratified Atmosphere Modelmentioning

confidence: 99%

“…The overall attenuation is acquired by integrating this parameter along the ray path using left Riemann sums. Another frequency-dependent effect to be considered is amplitude and phase fluctuations caused by turbulent scattering [15,27].…”

Section: Auralization Parametersmentioning

confidence: 99%

Atmospheric Ray Tracing: An efficient, open-source framework for finding eigenrays in a stratified, moving medium

Schäfer

Vorländer

2021

Acta Acust.

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In this paper, an open-source framework for ray tracing in a stratified moving medium is introduced. This framework provides an efficient method to find eigen-rays connecting a source with a receiver and is designed for the purpose of aircraft noise auralization. The method is tested with respect to accuracy and run-time in an aircraft flyover scenario and compared to a state of the art method. The investigation showed that this method provides eigenrays with preset accuracy for source positions most relevant for flyover scenarios and that it is significantly faster than the state of the art method. According to the performance analysis, the presented approach has great potential for integration into future real-time auralizations of aircraft noise.

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“…It was further found that the inclusion of the ground effect and amplitude fluctuations due to atmospheric turbulence 22 both serve to increase realism and plausibility of auralized flyovers. Ground effect, defined as the spectral pattern induced by interference of direct and ground reflected sound, is simulated here by an additional signal path that interferes with the direct sound signal.…”

Section: Ve Propagation Effectsmentioning

confidence: 99%

Simulation process for perception-based noise optimization of conventional and novel aircraft concepts

Pieren¹,

Bertsch

Blinstrub

et al. 2018

2018 AIAA Aerospace Sciences Meeting

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Noise from civil air traffic affects millions of people worldwide. Aircraft noise management should be addressed by different principal elements, such as noise reduction at the source and noise abatement operational procedures. To date, usually conventional noise metrics are applied towards the acoustical optimization while noise effects are usually only indirectly accounted for. The objective of this contribution is the optimization of conventional and novel aircraft concepts with respect to their evoked aircraft noise annoyance. The optimization will be based on the perceived sound and the associated annoyance. To do so, virtual aircraft flyovers are auralized based on noise level predictions, i.e. they are artificially made audible. The auralization is accomplished by parametric sound synthesis and a 3D spatial audio technique. Short-term noise annoyance is measured through controlled listening experiments in which participants rate the level of annoyance for each auralized flyover. The aircraft design and the flight path are evaluated according to the associated annoyance. The subsequent ranking can be compared to a "conventional" ranking based on standard noise metrics. The results of such a study will help to identify parameters describing aircraft and flight path parameters that have an impact on noise annoyance. Consequently, these parameters can then be selected for further optimization to reach even lower levels of noise annoyance and not simply reduce standard noise metrics. Ultimately, the main goal of the research is optimizing the noise annoyance of (novel) aircraft along tailored flight paths. This contribution documents the status quo of the joint DLR and Empa activities, i.e., the structure of a pilot study. First results that were obtained while developing the methodology and the test cases within the pilot study are presented.

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Generating Sequences of Acoustic Scintillations

Cited by 18 publications

References 12 publications

Objective quantification of perceived differences between measured and synthesized aircraft sounds

Objective quantification of perceived differences between measured and synthesized aircraft sounds

Atmospheric Ray Tracing: An efficient, open-source framework for finding eigenrays in a stratified, moving medium

Simulation process for perception-based noise optimization of conventional and novel aircraft concepts

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