NASA_FRDOC_0001-0959 Comment Responses 1
Response to NASA_FRDOC_0001-DRAFT-04060 1
Response to Comment on Questions (1) and (3) 2
Response to Comment on Ambient Noise 2
Response to Comment on Use Cases 3
Response to Comment on Vehicle Design and Operational Behaviors 3
Response to Comment on Masking and Existing Soundscape 3
Response to Comment on Metrics to Characterize Community Noise Exposure 3
Response to Comment on Data Availability and Disclosure 4
Response to Comment on Calibration of Test Sounds to Actual Recordings 4
Response to NASA_FRDOC_0001-DRAFT-0472 4
Response to On Practical Utility and Research Scope 4
Response to On Burden Estimate and Accessibility 5
Response to On Data Privacy and Informed Consent 5
Response to On Quality and Clarify of Data 5
Response to On Automated and Efficient Collection 5
Response to On Results Dissemination 6
Response to On Community Engagement 6
Response to On Utility for Future Noise Policy 6
Response to On Reducing Burden 6
Responses to the comments in Attachment 1 were included in the responses to comments for NASA_FRDOC_0001-0545, which was the 60-day notice for this information collection.
Attachment 2 of NASA_FRDOC-0001-DRAFT-04060 also correspond to NASA_FRDOC_0001-DRAFT-0463, NASA_FRDOC_0001-DRAFT-0467, NASA_FRDOC_0001-DRAFT-0468, and NASA_FRDOC_0001-DRAFT-0471. Therefore, these comments are addressed with the responses below to Attachment 2 of NASA_FRDOC-0001-DRAFT-04060.
The following are responses to Attachment 2 of NASA_FRDOC-0001-DRAFT-04060:
The VANGARD test will gather the annoyance response to different configurations of Advanced Air Mobility (AAM) aircraft to the extent that it is able to acquire the sounds of these different configurations. NASA, itself, does not possess the sounds of many AAM aircraft configurations. Access to sounds of multiple different AAM aircraft were sought for the VANGARD test. The VANGARD test will use metrics, like sound quality metrics, to describe the different configurations in ways that do not reveal the origin of the AAM aircraft because the AAM aircraft sounds were given to NASA with the agreement that their origin will not be revealed. Collaborations and partnerships with industry and other organizations that were generated in pursuit of completing the VANGARD test have allowed access to sounds of some different AAM aircraft configurations. Sounds of some other AAM aircraft configurations proved more challenging to acquire. The VANGARD test is proceeding with the sounds it was able to acquire.
The VANGARD test will provide data that can inform subsequent testing. The annoyance ratings of various AAM configurations in the VANGARD test can inform which aircraft sounds to include in subsequent testing that focus on investigating the effects of aircraft operational cadence, potentially operations along airspace corridors, and at different times of the day. These tests may eventually inform community noise surveys that establish exposure-response relationships like the Schultz curve. Test subject fatigue, personal time constraints, and probability of internet disconnection limits the duration of the VANGARD test. A limited duration also limits the number of parameters and stimuli that can be tested. The VANGARD test focuses on research objectives that are foundational towards understanding AAM noise response and for which an online test could be developed with limited resources. Understanding how different operational volumes, ambient noise levels, use cases, vehicle designs, and payloads affect annoyance response and how AAM vehicles will add noise events to various communities are important questions to answer. The VANGARD test cannot test all these important parameters due to its limited duration and the durations of individual AAM sound stimuli. These parameters can be explored in subsequent tests, to the extent that resources allow. Testing the effects of these other parameters on AAM noise response can be done in more controlled facilities than an online test application, but with likely fewer test subjects than the online test application. Response to noise at different distances from listener to AAM aircraft and differences between takeoff/landing will be gathered in the VANGARD test.
When the VANGARD test was being planned, an effort was made to acquire L90 values, but sources for the L90 values at different United States ZIP codes were unavailable to the test administrators. L50 values were available through National Park Service to initially designate “low” and “high” ambient noise areas. Categorizing areas based on L50 values generated by the National Park Service will be used for test subject recruitment. However, subsequent analyses of VANGARD test results do not have to use L50 values. After the VANGARD test is completed, an effort will be made to revisit sources of L90 values, which may potentially be available by the time the VANGARD test is completed, pending approval within NASA to use those sources. VANGARD test subject responses may be recategorized as coming from “low” and “high” ambient areas according to L90. VANGARD test responses and the corresponding test subject self-reported ZIP codes will be made publicly available so that others may analyze VANGARD test results with other ambient noise metrics, including L90.
The effect of use cases is an important aspect to understand regarding AAM noise annoyance. As stated earlier, limitations on the VANGARD test duration mean that this important research question will need to be answered in subsequent testing within the constraints of available testing resources.
While it is hypothesized that people will give low annoyance to cruise flight for AAM vehicles, it is less certain if similar ratings will be given for AAM takeoff/landing maneuvers. It is correct that takeoff/landing noise can vary depending on how the vehicle is flown. It is challenging to perform human noise response testing for all possible aircraft operational variations. Since little is currently known about how people will react to AAM takeoff/landing maneuvers, the VANGARD test will explore if general trends occur in the human response to takeoff/landing maneuvers with the sounds that are available for the test. It is understood that absolute annoyance ratings for a specific AAM aircraft may vary depending on how the vehicle is flown. For this reason, VANGARD test responses will be analyzed based on other metrics that define the sound characteristics, like sound quality metrics (e.g., roughness, tonality) and modulation envelopes. These metrics can be input to computational models that are based on responses from multiple psychoacoustic tests, like VANGARD, to predict the annoyance response to the noise from AAM aircraft with varied fight trajectories and operations without having to perform additional psychoacoustic testing. The VANGARD test will document distance between vehicle and listener, altitude, speed, and duration of exposure. Flight conditions will be described to the extent that the origin of the AAM vehicle sound stimuli are not revealed.
The effects of ambient noise masking on AAM noise annoyance is an important research question that is recognized by NASA. NASA has performed initial investigations into the effects of AAM noise response in the presence of masking sounds (Tracy, T., et al., “An annoyance model for urban air mobility vehicle noise in the presence of a masker,” INCE NOISE-CON 2024, 2024). As stated earlier, limitations on the VANGARD test duration mean that it is difficult to explore ambient noise effects in the VANGARD test. Subsequent test of ambient noise masking on AAM noise annoyance are being planned. Detectability indices of test subjects may need to be ascertained in tests on ambient noise masking. More confidence in detectability indices can be gained when the testing is performed in controlled test facilities rather than an online test application with varying and uncertain audio settings.
Test subject ZIP codes will be given and publicly released. These ZIP codes can be paired with ambient noise metrics like L90 and be used to determine proximity to airports and general aviation flight paths. Analyses of test results can account for participants’ existing noise environments to the resolution that ZIP codes allow.
Testing the effectiveness of metrics that measure long-term noise exposure, like DNL, N-Above, and N-Above-Ambient, will require community noise surveys that demand additional resources before they can be conducted. These additional resources are not available for the VANGARD test. VANGARD test results can inform the design of subsequent tests, including tests that investigate AAM noise with multiple flyovers and different aircraft types, which can then inform the design of community noise surveys that investigate the effectiveness of DNL, N-Above, N-Above-Ambient, and other long-term noise exposure metrics, including those with time-of-day penalties, on AAM noise community response.
NASA intends to publicly release VANGARD test results. NASA consulted with participants of the Urban Air Mobility Noise Working Group, which has participants from industry, academia, and other government agencies, to make the decision to release VANGARD test results. The publicly released test results will include annoyance responses from participants but no personally identifiable information will be associated with the responses. Test subject ZIP codes will be released and correspond with the responses. Test stimuli information will be released to the extent that the origin of the stimuli are not revealed and that the sound pressure time history of the stimuli cannot be reproduced. Stimuli descriptions or visual information will not be provided to test participants. Sound stimuli will not be stored on participant computers. Test participants are informed that their test responses and ZIP codes may be distributed for future analyses of the test results.
Test assumptions will be disclosed with test results to provide context.
NASA will publicly release a document describing how VANGARD test sounds were generated to the extent that the origin of sound stimuli are not revealed and that the sound pressure time histories of the stimuli are not revealed. While NASA can publicly share NASA AAM concept vehicles for efforts outside of the VANGARD test, it cannot reveal AAM aircraft used in the VANGARD test because sounds of different AAM vehicles were provided to NASA with the agreement that their origin will not be disclosed. In acquiring the AAM sounds, VANGARD test administrators worked to acquire real AAM acoustic data to the extent possible with the resources available. Using its aircraft noise auralization capabilities, NASA has reprocessed VANGARD AAM sounds so that the sounds correspond to comparable conditions of distance, altitude, duration of exposure, ground reflections, and atmospheric attenuation.
VANGARD test administrators at NASA thank the public for its support. The VANGARD test is designed to provide findings on AAM noise response that can be used to inform the design of subsequent tests that investigate additional parameters that reflect how impacted communities experience noise.
The VANGARD test administrators at NASA thank the commentor for their comments.
A limitation on resources have prevented VANGARD test administrators from using test participant selection methods that provide demographic representativeness of geographic regions beyond aggregate age range and “male” or “female” distributions. That is one reason why the VANGARD test objectives are not designed to affect existing or proposed aircraft operations or actions taken in reaction to those operations. There is little understanding of human noise response to AAM vehicles, and the VANGARD test seeks to provide data for this understanding. Knowledge gained from the VANGARD test on AAM noise response can inform the design of subsequent AAM noise human response tests that explore parameters like number of events and ambient noise masking effects that the VANGARD test could not investigate. Results from these tests and VANGARD can inform community noise surveys that are like the FAA’s Neighborhood Environmental Survey which, with the resources to conduct such surveys, can have demographically representative participants. VANGARD test results on how participants in “low” and “high” ambient regions react to AAM noise will be initial findings that can be investigated more carefully with subsequent testing where demographic representativeness is obtained.
The NASA Remote Psychoacoustic Test Platform from which the VANGARD test application is accessed complies with Section 508 of the Rehabilitation Act of 1973 to allow people with disabilities to use the test application. While the test application may potentially be accessed on general mobile devices, test participants will be asked to use computers running Windows 10+ or Mac OS 11 or later. The test application has not been verified to run properly on devices that do not use these two operating systems. VANGARD test subject recruitment will occur in English. Therefore, VANGARD test participants will likely be able to read and understand English, and the VANGARD test will occur in English. While these requirements limit certain people from participating, the VANGARD test objectives do not require a demographically representative test subject pool. Additional resources beyond what was available to VANGARD test administrators would be needed for future testing with the NASA Remote Psychoacoustic Test Platform where demographic representativeness is required. Test administrators would need the additional resources to verify that the test application operates well on mobile devices and that the test can be accessed in multiple languages.
Informed Consent and Privacy Act Notice documents will be provided to VANGARD participants that detail test procedures, potential benefits, compensation, potential risks, how confidentiality will be maintained, and that participants may withdraw from the test at any time. Participants are informed that personal information used to access the test application will only be retained until the test is completed, and that personally identifiable information will be disassociated from test responses and ZIP codes after the test is completed.
A post-test questionnaire on noise sensitivity is provided at the end of the main VANGARD test. The noise sensitivity questions ask respondents to select along a numerical rating scale. The noise sensitivity questions are designed to offer some insight into the lived experience of respondents but do not collect personally identifiable information. The VANGARD test application is not currently set up to accept open-ended questions. Configuring the VANGARD test application to accept open-ended questions will require additional review and planning on how personally identifiable information that is inadvertently entered into the open-ended questions will be handled.
As soon as
responses are entered, test responses are stored on the NASA Amazon
Web Services account from which the test is deployed. Responses are
returned to the NASA Amazon Web Services in the form of numerical
ratings. Testing of the NASA Remote Psychoacoustic Testing Platform
has not revealed that returned numerical ratings may be different
than what respondents have entered. VANGARD test participants are
given test support contact information and can contact the test
administrators if they are having problems completing the VANGARD
test.
Response
to On Demographic and Environmental Data Granularity
The ZIP codes that are reported by VANGARD test participants can correspond to ambient noise levels and demographic variables that are given by various sources, including the National Park Service. No other personally identifiable information is connected to the ZIP codes. Analyses of VANGARD responses will relate ambient noise levels of ZIP codes to test responses. While understanding how demographic variables in ZIP codes relate to test responses is not a VANGARD test objective, analyses of these variables may be performed by others after public release of the VANGARD test responses and the corresponding ZIP codes.
NASA will publish anonymized, disaggregated test results, including subgroup analyses, in open-access formats to support public understanding and enable third-party research.
In working with organizers of the 2025 Aviation Noise and Emissions Symposium, which included those from community organizations, NASA presented on its human noise response research, including the VANGARD test, to make the public aware of the VANGARD test. NASA has also presented on its Remote Psychoacoustic Testing Platform and VANGARD test at multiple technical conferences, working groups, and workshops (NASA Acoustics Technical Working Group Meetings, 2020-2025; SAE Noise and Vibration Conference and Exhibition 2023; INCE NOISE-CON 2022; Advances in Noise Control Engineering, A NAE-Hosted Workshop, 2021; Environmental Issues in Aviation Committee, Transportation Research Board, 2021).
With a limitation on resources that prevented VANGARD test administrators from using test participant selection methods that provide demographic representativeness of geographic regions, the VANGARD test seeks to gather initial findings on AAM noise response, of which insufficient information currently exists, to inform the design of subsequent tests on AAM noise response. To conduct these subsequent tests, NASA may potentially be partnered with other organizations that, together, provide sufficient resources to use respondent selection methods that achieve demographic representativeness.
NASA is currently planning a roadmap for how AAM human noise response testing, of which VANGARD is one of many tests, can inform the design of community noise surveys that generate exposure-response relationships to inform AAM noise regulations and mitigation.
The NASA Remote Psychoacoustic Test Platform from which the VANGARD test will be accessed allows respondents to pause the test and return to the test from the point that they left. While a post-test questionnaire is not provided to gather information on noise-sensitivity, the VANGARD test application is not currently set up to accept open-ended questions on barriers encountered during testing. Configuring the VANGARD test application to accept open-ended questions will require additional review and planning on how personally identifiable information that is inadvertently entered into the open-ended questions will be handled. Respondents may contact test administrators if they have problems during testing, to make comments, or ask questions at any point in the test or after they complete the test. To improve future collections, general trends in problems/barriers encountered during testing will be noted and subsequently documented by test administrators without involving test respondent details.
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| File Type | application/vnd.openxmlformats-officedocument.wordprocessingml.document |
| Author | Tracy, Tyler D. (LARC-D321) |
| File Modified | 0000-00-00 |
| File Created | 2025-06-11 |