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Stephen Rizzi

Publications and source records attributed to Stephen Rizzi.

17 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2024

An Annoyance Model for Urban Air Mobility Vehicle Noise in the Presence of a Masker

Proposed Urban Air Mobility (UAM) operations offer an alternative to road and rail traffic for local and regional movement of people and goods. To allow for large-scale adoption of UAM vertical takeoff and landing (VTOL) aircraft, it is critical to predict human annoyance response to the acoustic noise generated by these vehicles. We propose a model that predicts an individual’s perceived level of annoyance when presented with UAM VTOL aircraft noise in the context of a representative masking noise. The annoyance model is based on the psychoacoustic annoyance model of Fastl and Zwicker (Zwicker and Fastl, 1999), with an additional tonality term based on subjective testing of UAM sound quality (Boucher, et al., 2023). The model also predicts changes in annoyance when UAM noise is masked by a background sound, based on subjective evaluation of detection, noticeability, and annoyance of noise in the presence of a masker.

Noise↗
NASA NTRS2023

Acoustics Technical Working Group and UAM Noise Working Group Proceedings

The NASA Acoustics Technical Working Group Meeting originally started as a program planning meeting in 1992 and has grown through the years. The purpose of these biannual meetings is to foster communication and collaboration among NASA researchers and their university, industry, and government colleagues on activities and work of current and future mutual interest. The NASA-led Urban Air Mobility (UAM) Noise Working Group (UNWG) Meeting began in 2018 as a one-day meeting immediately following the Acoustics Technical Working Group Meeting. The UNWG utilizes four subgroups that conduct regular meetings throughout the year to focus on challenges facing UAM vehicles for community noise and acceptance. The four subgroups coordinate research for development of noise prediction tools/noise reduction technologies, ground and flight test methods, human response and metrics, and regulations and policy (led by the FAA). This work is a compilation of the presentations given at ATWG/UNWG Fall 2022 held in person and via Teams at NASA Glenn Research Center. All NASA content was previously submitted through STRIVES for public presentation. This is merely a compilation. Non-NASA content has permission to distribute. Slide 208 video is included in the Available Downloads as Medial.MOV.

Advanced Air Mobility↗
NASA NTRS2014

TPSAS-NF1676L-17844-DND

Distributed propulsion is being proposed as an approach to achieve greater aircraft efficiency. An added benefit which might be realized with a distributed propulsion configuration is a reduction in radiated sound power. A reduction in radiated sound power could relieve concerns related to an increase in community noise that would accompany the adaptation of a fleet of many small aircraft fielded to meet increased travel demand. However, a reduction in radiated sound power does not necessarily translate into community acceptance of the new noise signature. Some characteristics of distributed propulsion configurations can create aural effects that people would find more annoying even though the sound is at a lower power level. To understand the community response to the new class of noise that a distributed propulsion system would present requires the prediction, synthesis and auralization of the noise in a controlled environment. Representative members of the community can then be exposed to the noise and queried for their reaction. These are the types of tests performed in NASA Langley’s Exterior Effects Room. This report summarizes preliminary results obtained using isolated propeller predictions. The sound pressure level of a single ‘large’ propeller is compared to that of two ‘smaller’ propellers of equivalent total thrust. The aural effects of different implementations of the two propellers are also considered. The different implementations include rotation direction and blade passage frequency separation.

Dan Palumbo↗
NASA NTRSDate not supplied

Recalibration of the NASA Exterior Effects Room

The Exterior Effects Room (EER) is a psychoacoustic testing facility at NASA Langley Research Center which primarily focuses on testing human response to aircraft noise. The 39-seat auditorium houses a real-time spatial audio system and flyover simulation environment. The audio server utilizes an implementation of three-dimensional vector base amplitude panning (VBAP), a perceptual spatial audio technique exploiting loudspeaker triplets to place a virtual sound source at an arbitrary spatial position. Due to the irregular room geometry and non-uniform loudspeaker setup, the audio server applies equalization filtering to compensate for spectral coloration attributed to loudspeaker installation, crossover filtering, and delay/gain offsets. These filters can incorporate measurements taken at multiple listening points, allowing a more extensive listening area than filters derived from measurements taken at a single listening point. This work endeavors to update the existing equalization filter generation process by producing a new set of filters for various human subject testing scenarios.

calibration↗
NASA NTRSDate not supplied

Recalibration of the NASA Exterior Effects Room

The Exterior Effects Room (EER) is a psychoacoustic testing facility at NASA Langley Research Center which primarily focuses on testing human response to aircraft noise. The 39-seat auditorium houses a real-time spatial audio system and flyover simulation environment. The audio server utilizes an implementation of three-dimensional vector base amplitude panning (VBAP), a perceptual spatial audio technique exploiting loudspeaker triplets to place a virtual sound source at an arbitrary spatial position. Due to the irregular room geometry and nonuniform loudspeaker setup, the audio server applies equalization filtering to compensate for spectral coloration attributed to loudspeaker installation, crossover filtering, and delay/gain offsets. These filters can incorporate measurements taken at multiple listening points, allowing a more extensive listening area than filters derived from measurements taken at a single listening point. This work endeavors to update the existing equalization filter generation process by producing a new set of filters for various human subject testing scenarios.

Signal Processing↗
NASA NTRSDate not supplied

Remotely Administered Psychoacoustic Test for sUAS Noise to Gauge Feasibility of Remote UAM Noise Study

The National Aeronautics and Space Administration (NASA) remotely administered a psychoacoustic test in fall of 2022 as the first of two phases of a cooperative Urban Air Mobility (UAM) vehicle noise human response study. The first phase, the Feasibility Test, described in this paper, determined the feasibility of the remote test method, in contrast to a previous in-person psychoacoustic test that found an annoyance response difference between small unmanned aerial system (sUAS) noise and ground vehicle noise. This paper discusses the Feasibility Test online layout, sound calibration method, remote test software development, stimuli selection, test subject recruitment, and test administration. Test performance is measured through comparison of annoyance response data with the previous in-person test results. The paper also investigates if providing a contextual cue to test subjects influenced their annoyance response. Response differences between test subjects in geographically distinct areas are analyzed. Administrative challenges that were encountered during the test are discussed. The second phase of this study, the implementation phase, will use a remote (web-based) test method and leverage the cooperation of multiple government agencies, academia, and industry to gain human response insights from a wide range of UAM vehicle sounds that would be challenging for a single organization to acquire. Improvements to administering a remote test for the implementation phase of the UAM vehicle noise human response study are recommended.

Remote Psychoacoustic Test↗
NASA NTRSDate not supplied

A Psychoacoustic Test for Urban Air Mobility Vehicle Sound Quality

This paper describes a psychoacoustic test in the Exterior Effects Room (EER) at the NASA Langley Research Center. The test investigated the degree to which sound quality metrics (sharpness, tonality, etc.) are predictive of annoyance to notional sounds of Urban Air Mobility (UAM) vehicles (i.e., air taxis). A suite of 136 unique (4.6 second duration) UAM rotor noise stimuli was generated. These stimuli were based on aeroacoustic predictions of a NASA reference UAM quadrotor aircraft under two flight conditions. The synthesizer changed rotor noise parameters such as the blade passage frequency, the relative level of broadband self-noise, and the relative level of tonal motor noise. With loudness constant, the synthesis parameters impacted sound quality in a way that created a spread of predictors both in synthesizer parameters and in sound quality metrics. Forty subjects listened to the suite of UAM noise stimuli in the EER and judged each sound individually on a standard scale of annoyance. Additionally, a subset of the UAM noise stimuli were compared to a reference sound that varied in loudness. From these responses, the relative effect of changes in loudness or changes in other sound quality metrics on annoyance was evaluated. This paper covers background and motivation for the test, details of how the sound stimuli were generated, and details of the test design and execution. Test results investigate how sound quality may affect perceived annoyance to UAM vehicle noise, indicating the importance of sharpness, tonality, impulsiveness, and roughness on annoyance to UAM noise.

UAM↗
NASA NTRSDate not supplied

A Psychoacoustic Test on the Effect of Masking on Annoyance to Urban Air Mobility Vehicle Noise

Urban Air Mobility (UAM) vehicles have a large range of designs and configurations that lead to new noise characteristics and potentially different perceptual responses when compared to traditional aircraft. In addition, UAM vehicles are expected to operate around and within densely populated regions where the presence of ambient background noise is often present. Strategically, this can be leveraged to inform vehicle design and operations to partially or completely mask UAM noise, allowing for mitigation of negative responses and an increased number of allowed operations. A psychoacoustic test was conducted to investigate how masking effects can influence the annoyance response to a low frequency harmonic tone complex (80-320 Hz). To do this, five test subjects compared their annoyance response to the low frequency tonal noise with a higher frequency broadband noise (10dB down bandwidth between 300-2000 Hz), with and without a masking noise present. Detection thresholds were also measured for both sounds to help fit a model to the data. Although the effect of masking on annoyance is complex, results indicate that for some individuals, masking leads to a lower annoyance than the sound level alone would predict.

Matthew Boucher↗