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Project Title:  Space Craft Internal Acoustic Environment Reduce
Fiscal Year: FY 2011 
Division: Human Research 
Research Discipline/Element:
HRP SHFH:Space Human Factors & Habitability (archival in 2017)
Start Date: 10/02/2006  
End Date: 09/30/2011  
Task Last Updated: 09/30/2011 
Download report in PDF pdf
Principal Investigator/Affiliation:   Allen, Christopher S M.S. / Lockheed-Martin/ NASA Johnson Space Center 
Address:  2101 Nasa Parkway 
Mail Code SF22 
Houston , TX 77058 
Email: christopher.s.allen@nasa.gov 
Phone: 281.483.9710  
Congressional District: 22 
Web:  
Organization Type: INDUSTRY 
Organization Name: Lockheed-Martin/ NASA Johnson Space Center 
Joint Agency:  
Comments:  
Co-Investigator(s)
Affiliation: 
Chu, S. Reynold  Lockheed/NASA Johnson Space Center 
Project Information: Grant/Contract No. Directed Research 
Responsible Center: NASA JSC 
Grant Monitor: Woolford, Barbara  
Center Contact: 218-483-3701 
barbara.j.woolford@nasa.gov 
Solicitation / Funding Source: Directed Research 
Grant/Contract No.: Directed Research 
Project Type: GROUND 
Flight Program:  
TechPort: No 
No. of Post Docs:
No. of PhD Candidates:
No. of Master's Candidates:
No. of Bachelor's Candidates:
No. of PhD Degrees:
No. of Master's Degrees:
No. of Bachelor's Degrees:
Human Research Program Elements: (1) SHFH:Space Human Factors & Habitability (archival in 2017)
Human Research Program Risks: (1) Hab:Risk of an Incompatible Vehicle/Habitat Design
Human Research Program Gaps: (1) SHFE-HAB-01:What validated acoustic model can predict the effects of structures, materials, crew and equipment on the acoustic environment of a spacecraft or habitat? (CLOSED, per IRP Rev F)
Flight Assignment/Project Notes: NOTE: End date is 9/30/2011, per A. Foerster/JSC (5/2010)

Task Description: Acoustic modeling can be used to identify key noise sources, determine/analyze sub-allocated requirements, keep track of the accumulation of minor noise sources, and to predict vehicle noise levels at various stages in the development, first with estimates of noise sources, later with experimental data. Bench testing of isolated systems alone is not sufficient as the installation effects are often not known. Acoustic modeling will be used to determine installation effects, reverberation (room geometry) effects, and will be used to identify propagation paths and possible noise controls, as well as develop an understanding of the resulting acoustic levels in the composite environment. Finally, acoustic modeling will be used to assist with the development and implementation of spaceflight acoustic materials and to predict their effectiveness including sound containment, absorption, and vibration isolation. Prior to this project, NASA did not have institutional acoustic modeling capability in regards to spaceflight vehicles. Through this project, acoustic modeling capability is being developed for application to Orion and other new spaceflight vehicles to ensure a sufficiently quiet environment in which the astronaut crews can work and live.

In general, modern acoustic modeling techniques such as Statistical Energy Analysis (SEA), Ray-tracing techniques, and Finite Element Methods have been used effectively to reduce interior noise in automotive, aircraft, and some spacecraft designs. Each method has its own strengths depending on the type of noise being modeled and the assumptions used, but it is clear that these methods have been effective; automotive and aircraft noise levels have been substantially reduced in recent years. Also, the continued development, current sophistication, and rising sales of off-the-shelf acoustic modeling software are indicative of their applicability and success; otherwise the companies that build automobiles and aircraft would not purchase these. See Reference 1 for a recent article describing the state of the art in acoustic modeling capabilities, including off-the-shelf acoustic modeling software tools.

The objective of this project will be to develop an acoustic modeling capability, based on off-the-shelf software, to be used as a tool for oversight of the future manned spaceflight vehicles to ensure compliance with acoustic requirements and thus provide a safe and habitable acoustic environment for the crews.

Reference

1. von Estorff, Otto, “NUMERICAL METHODS IN ACOUSTICS: FACTS, FEARS, FUTURE,” 19th INTERNATIONAL CONGRESS ON ACOUSTICS, Madrid, September 2007.

Research Impact/Earth Benefits: • Demonstrated the development of spacecraft cabin acoustic models and a model validation technique using acoustic mockups with incrementally increasing fidelity.

• Observed great utility and capability of the Statistical Energy Analysis (SEA) acoustic modeling method both in the accuracy of the results (in the applicable frequency range), and in the geometrical complexity that can be accommodated.

• Reversed the Orion team decision to push back (up) the Orion cabin noise limit.

• Prompted the formation of the Orion Acoustic Working Group for resolving Orion cabin acoustics related issues.

• Prompted Lockheed Martin to hire a vibro-acoustics engineer for crew module (CM) cabin acoustic environment modeling and analysis.

• Developed Level 2 requirements for the CM Snorkel Fan and the Waste Management System. The Snorkel Fan requirement is to limit pre-launch and post-landing Speech Interference Levels.

• Initiated a collaborated effort with Lockheed Martin staff for Orion CM cabin acoustic environment modeling and analysis. The findings described in this report were provided to Lockheed Martin staff, helping to promote and validate similar system-level noise treatments for the actual Orion vehicle. This resulted in the acceptance of a mass allocation for the system-level noise treatments, which were then assigned to various Orion system teams for implementation.

Task Progress & Bibliography Information FY2011 
Task Progress: The activity of this research implements acoustic modeling for design purposes by incrementally increasing model fidelity and validating the accuracy of the model which predicts the sound pressure levels (SPLs) produced by sources under various conditions. An International Space Station (ISS) US Lab mockup and an Orion Crew Module (CM) acoustic mockup were used for modeling validation.

For the ISS US Lab mockup, three mockup interior reverberant environments were modeled and validated successfully using single and dual airborne sound sources with known sound power levels. Two methods were developed to model the mockup interior absorption: one was based on the measurement of mockup interior reverberation time; the other was based on impedance tube measurement of sound absorptive material used to cover the interior surfaces of the mockup. The effect of source location on the accuracy of the model predictions under a highly absorptive mockup interior was observed. Furthermore, strategy was developed to model the SPL distribution in a large mockup with a highly absorptive interior.

The modeling of the Orion CM acoustic mockup involved more complex geometrical shape and ventilation fan with unknown sound power levels beforehand. Sound power levels of the ventilation fans were estimated from sound intensity measurements. The fidelity of the mockup and the model were increased from an empty interior in the beginning to include an ECLSS (Environmental Control and Life Support System) wall and ECLSS bay with open/sealed gaps between the ECLSS wall and the mockup wall. There were two configurations of sound absorptive Thinsulate attached to the surfaces of the ECLSS wall panels. An effective method of deploying sound absorptive material in reducing cabin SPL was discovered by modeling and validated by measurement. The effect of sealing the gaps to prevent noise from leaking into the cabin was also modeled and validated. Lastly, a bare Orion CM mockup with aluminum interior walls was also modeled and validated. The purpose of the study was to increase the mockup interior reverberation time to the level typical of a spacecraft pressure vessel interior.

Also, lessons were learned regarding the problem of absorption coupling between adjacent cavities, e.g., cabin and ECLSS bay in the CM mockup, and the problem of Damping Loss Factor sensitivity when modeling structure-borne noise.

Bibliography Type: Description: (Last Updated: 08/31/2018) 

Show Cumulative Bibliography Listing
 
Abstracts for Journals and Proceedings Dandaroy I, Chu SR. "Cabin Noise Studies for the Orion Spacecraft Crew Module." Presentation at the Spacecraft and Launch Vehicle Dynamic Environments Workshop, The Aerospace Corporation, El Segundo, Calif., June 7-9, 2011.

Spacecraft and Launch Vehicle Dynamic Environments Workshop, The Aerospace Corporation, El Segundo, Calif., June 7-9, 2011. , Jun-2011

Abstracts for Journals and Proceedings Chu SR, Allen CS. "Spacecraft Internal Acoustic Environment Modeling." Space Human Factors and Habitability Poster Session. Poster Presentation at the NASA Human Research Program Investigators' Workshop, Houston, TX, February 3-5, 2010.

NASA Human Research Program Investigators' Workshop, Houston, TX, February 3-5, 2010. , Feb-2010

Abstracts for Journals and Proceedings Chu SR, Allen CS. "Spacecraft Internal Acoustic Environment Modeling." Poster Presentation at Inadequate Design Risk Session, NASA Human Research Program Investigators’ Workshop, League City, TX, February 2-4, 2009.

NASA Human Research Program Investigators’ Workshop, League City, TX, February 2-4, 2009. , Feb-2009

Abstracts for Journals and Proceedings Chu SR, Allen CS. "Spacecraft Internal Acoustic Environment Modeling." Poster Presentation at the Space Human Factors and Habitability Poster Session, NASA Human Research Program Investigators’ Workshop, League City, TX, February 4-6, 2008.

NASA Human Research Program Investigators’ Workshop, League City, TX, February 4-6, 2008. , Feb-2008

Papers from Meeting Proceedings Chu SR, Allen CS. "Spacecraft Cabin Acoustic Modeling and Validation with Mockups." 41st International Conference on Environmental Systems, Portland, Oregon, July 17-21, 2011. (Presentation on July 19).

41st International Conference on Environmental Systems, Portland, Oregon, July 17-21, 2011. Paper AIAA-2011-5112. http://arc.aiaa.org/doi/abs/10.2514/6.2011-5112 ; accessed 7/7/15. , Jul-2011

Project Title:  Space Craft Internal Acoustic Environment Reduce
Fiscal Year: FY 2010 
Division: Human Research 
Research Discipline/Element:
HRP SHFH:Space Human Factors & Habitability (archival in 2017)
Start Date: 10/02/2006  
End Date: 09/30/2011  
Task Last Updated: 12/03/2010 
Download report in PDF pdf
Principal Investigator/Affiliation:   Allen, Christopher S M.S. / Lockheed-Martin/ NASA Johnson Space Center 
Address:  2101 Nasa Parkway 
Mail Code SF22 
Houston , TX 77058 
Email: christopher.s.allen@nasa.gov 
Phone: 281.483.9710  
Congressional District: 22 
Web:  
Organization Type: INDUSTRY 
Organization Name: Lockheed-Martin/ NASA Johnson Space Center 
Joint Agency:  
Comments:  
Co-Investigator(s)
Affiliation: 
Chu, S. Reynold  Lockheed/NASA Johnson Space Center 
Project Information: 
Responsible Center: NASA JSC 
Grant Monitor: Woolford, Barbara  
Center Contact: 218-483-3701 
barbara.j.woolford@nasa.gov 
Solicitation / Funding Source: Directed Research 
Project Type: GROUND 
Flight Program:  
TechPort: No 
No. of Post Docs:
No. of PhD Candidates:
No. of Master's Candidates:
No. of Bachelor's Candidates:
No. of PhD Degrees:
No. of Master's Degrees:
No. of Bachelor's Degrees:
Human Research Program Elements: (1) SHFH:Space Human Factors & Habitability (archival in 2017)
Human Research Program Risks: (1) Hab:Risk of an Incompatible Vehicle/Habitat Design
Human Research Program Gaps: (1) SHFE-HAB-01:What validated acoustic model can predict the effects of structures, materials, crew and equipment on the acoustic environment of a spacecraft or habitat? (CLOSED, per IRP Rev F)
Flight Assignment/Project Notes: NOTE: End date supposed to be 9/30/2011, per A. Foerster/JSC (5/2010)

Task Description: Acoustic modeling can be used to identify key noise sources, determine/analyze sub-allocated requirements, keep track of the accumulation of minor noise sources, and to predict vehicle noise levels at various stages in the development, first with estimates of noise sources, later with experimental data. Bench testing of isolated systems alone is not sufficient as the installation effects are often not known. Acoustic modeling will be used to determine installation effects, reverberation (room geometry) effects, and will be used to identify propagation paths and possible noise controls, as well as develop an understanding of the resulting acoustic levels in the composite environment. Finally, acoustic modeling will be used to assist with the development and implementation of spaceflight acoustic materials and to predict their effectiveness including sound containment, absorption and vibration isolation. Prior to this project, NASA did not have institutional acoustic modeling capability in regards to space flight vehicles. Through this project, acoustic modeling capability is being developed for application to Orion and other new spaceflight vehicles to ensure a sufficiently quiet environment in which the astronaut crews can work and live.

In general, modern acoustic modeling techniques such as Statistical Energy Analysis (SEA), Ray-tracing techniques, and Finite Element Methods have been used effectively to reduce interior noise in automotive, aircraft, and some spacecraft designs. Each method has its own strengths depending on the type of noise being modeled and the assumptions used, but it is clear that these methods have been effective; automotive and aircraft noise levels have been substantially reduced in recent years. Also, the continued development, current sophistication, and rising sales of off-the-shelf acoustic modeling software are indicative of their applicability and success, otherwise the companies that build automobiles and aircraft would not purchase these. See reference 1 for a recent article describing the state of the art in acoustic modeling capabilities, including off-the-shelf acoustic modeling software tools.

The objective of this project will be to develop an acoustic modeling capability, based on off-the-shelf software, to be used as a tool for oversight of the future manned spaceflight vehicles to ensure compliance with acoustic requirements and thus provide a safe and habitable acoustic environment for the crews.

Research Impact/Earth Benefits: Discoveries/advancements on how best to model certain geometrical/physical aspects of enclosed spaces (such as flight vehicles) will be shared with the acoustic modeling community.

Task Progress & Bibliography Information FY2010 
Task Progress: The Acoustics Modeling Project has had several accomplishments during FY’10. These accomplishments included 1) advancing the validation of acoustic modeling techniques, 2) participating in a collaborative acoustic modeling effort on Orion 606g and 606h versions of the Crew Module, and 3) identifying and validating specific noise controls for use in the Orion vehicle.

1) The acoustic modeling method was validated regarding important secondary structure, e.g. closeout panels. In particular, the acoustic transmission properties of the Orion secondary structure partition (that separates the crew habitable volume from the environmental control system’s fans and pumps) was modeled and mocked-up inside the Orion Acoustic Mockup with a realistic fan noise source located behind the partition. The predictions and measurements were in good agreement, thus validating the modeling approach. In addition to the panel validation, transmission loss modeling representation of acoustic blocking materials was validated against the model’s “mass law” representation.

2) In collaboration with the Orion Prime Contractor, a detailed acoustic model of the Orion Crew Module version 606h was developed. Later in the year this model was collaboratively updated to revision 606g, the latest version of the full-capability Orion Crew Module. This model was used to advocate the development of “system-level” noise treatments (see below) to aide in the global reduction of noise levels in the Crew Module. The benefit of this approach was to enable development of “component noise allocations” that the fan and pump developer could achieve in order to meet the acoustic requirements.

3) Finally, the Acoustic Modeling Project made recommendations of noise treatments, specifically the acoustical sealing of gaps around the closeout partition (mentioned above) and the addition of acoustically absorbent treatments to some surfaces inside the Crew Module. These noise controls were modeled and mocked-up in the Orion Acoustics Mockup and their acoustical advantages were validated. This information, along with further modeling of noise control trade studies, acoustic flight-materials investigations, and implementation studies (performed by Orion Prime) were presented to management in order to obtain mass-budget of 35 lbs, and hardware ownership of the noise treatments in order for their implementation.

As a result of the above achievements, the prospect of the Orion Crew Module meeting the stringent acoustic requirements has been greatly increased.

Bibliography Type: Description: (Last Updated: 08/31/2018) 

Show Cumulative Bibliography Listing
 
 None in FY 2010
Project Title:  Space Craft Internal Acoustic Environment Reduce
Fiscal Year: FY 2009 
Division: Human Research 
Research Discipline/Element:
HRP SHFH:Space Human Factors & Habitability (archival in 2017)
Start Date: 10/02/2006  
End Date: 09/30/2011  
Task Last Updated: 05/04/2010 
Download report in PDF pdf
Principal Investigator/Affiliation:   Allen, Christopher S M.S. / Lockheed-Martin/ NASA Johnson Space Center 
Address:  2101 Nasa Parkway 
Mail Code SF22 
Houston , TX 77058 
Email: christopher.s.allen@nasa.gov 
Phone: 281.483.9710  
Congressional District: 22 
Web:  
Organization Type: INDUSTRY 
Organization Name: Lockheed-Martin/ NASA Johnson Space Center 
Joint Agency:  
Comments:  
Co-Investigator(s)
Affiliation: 
Chu, S. Reynold  Lockheed/NASA Johnson Space Center 
Project Information: 
Responsible Center: NASA JSC 
Grant Monitor: Woolford, Barbara  
Center Contact: 218-483-3701 
barbara.j.woolford@nasa.gov 
Solicitation / Funding Source: Directed Research 
Project Type: GROUND 
Flight Program:  
TechPort: No 
No. of Post Docs:
No. of PhD Candidates:
No. of Master's Candidates:
No. of Bachelor's Candidates:
No. of PhD Degrees:
No. of Master's Degrees:
No. of Bachelor's Degrees:
Human Research Program Elements: (1) SHFH:Space Human Factors & Habitability (archival in 2017)
Human Research Program Risks: (1) Hab:Risk of an Incompatible Vehicle/Habitat Design
Human Research Program Gaps: (1) SHFE-HAB-01:What validated acoustic model can predict the effects of structures, materials, crew and equipment on the acoustic environment of a spacecraft or habitat? (CLOSED, per IRP Rev F)
Flight Assignment/Project Notes: NOTE: End date supposed to be 9/30/2011, per A. Foerster/JSC (5/2010)

Task Description: Acoustic modeling can be used to identify key noise sources, determine/analyze sub-allocated requirements, keep track of the accumulation of minor noise sources, and to predict vehicle noise levels at various stages in the development, first with estimates of noise sources, later with experimental data. Bench testing of isolated systems alone is not sufficient as the installation effects are often not known. Acoustic modeling will be used to determine installation effects, reverberation (room geometry) effects, and will be used to identify propagation paths and possible noise controls, as well as develop an understanding of the resulting acoustic levels in the composite environment. Finally, acoustic modeling will be used to assist with the development and implementation of spaceflight acoustic materials and to predict their effectiveness including sound containment, absorption and vibration isolation. Prior to this project, NASA did not have institutional acoustic modeling capability in regards to space flight vehicles. Through this project, acoustic modeling capability is being developed for application to the Cx (Constellation) Program and its new spaceflight vehicles to ensure a sufficiently quiet environment in which the astronaut crews can work and live.

In general, modern acoustic modeling techniques such as Statistical Energy Analysis (SEA), Ray-tracing techniques, and Finite Element Methods have been used effectively to reduce interior noise in automotive, aircraft, and some spacecraft designs. Each method has its own strengths depending on the type of noise being modeled and the assumptions used, but it is clear that these methods have been effective; automotive and aircraft noise levels have been substantially reduced in recent years. Also, the continued development, current sophistication, and rising sales of off-the-shelf acoustic modeling software are indicative of their applicability and success, otherwise the companies that build automobiles and aircraft would not purchase these. See reference 1 for a recent article describing the state of the art in acoustic modeling capabilities, including off-the-shelf acoustic modeling software tools.

The objective of this project will be to develop an acoustic modeling capability, based on off-the-shelf software, to be used as a tool for oversight of the future manned Constellation vehicles to ensure compliance with acoustic requirements and thus provide a safe and habitable acoustic environment for the crews. During FY’07, the project’s first year, this project:

1. Determined the acoustic modeling requirements for Constellation vehicles, in terms of frequency range, source type, and model type, and leased an off-the-shelf software package that is well-suited for the modeling task.

2. Developed a simple-geometry acoustic model and validated the model using a physical mockup and acoustic measurements. Tools for modeling the effects of absorptive wall treatments and the resulting reverberation environment were developed as part of this work. Limitations of the modeling technique were also investigated and documented.

Research Impact/Earth Benefits: Discoveries/advancements on how best to model certain geometrical/physical aspects of enclosed spaces (such as flight vehicles) will be shared with the acoustic modeling community.

Task Progress & Bibliography Information FY2009 
Task Progress: In FY’09, significant progress was made with validation and development of the acoustic modeling technique. This included:

• Modified the acoustic reverberation time of the CM mockup to match the reverberation time inside the ISS US Lab in the speech bands, i.e. 0.5, 1, 2, and 4 kHz, for evaluating CM Snorkel Fan noise on post-landing crew communications. Thinsulate© sound absorption material was attached to the interior surface of the mockup to achieve this purpose. An SEA acoustic model of the CM mockup was used to predict the amount of acoustic treatment required, and reverberation time measurements were made to verify the match to the desired reverberation environment.

• Validated the SEA model in predicting mockup interior SPLs (Sound Pressure Levels) due to the emissions of realistic ventilation fan sources. The sound power levels of these fan sources were unknown a priori. Sound power levels of these fan sources were estimated using a sound intensity measurement technique. This is opposed to prior studies where a RSS (Reference Sound Source) with known calibrated sound power was used.

A measurement grid system of rectangular box shape was built for sound intensity measurements. The grid system enclosed the source to be measured with five surfaces, i.e., front, right, back, left, and top. Sound intensity at the center of each segment of the grid system was measured and time averaged for 15 sec. Sound intensity at the bottom surface reflected most of the incident sound energy so that it was accounted for at the other measured surfaces. Non-stationary background noise of the Chamber was of concern because it could introduce some net error on estimated fan sound power. The technique of estimating sound power via sound intensity measurements can cancel out only stationary background noise sources outside the grid system.

Acoustic testing was performed in the Orion CM mockup, and comparisons were made with acoustic modeling predictions. The comparisons showed very good agreement, plus or minus 3 dB above the Schroder frequency (where SEA is expected to give good results). The case studied was very realistic as the sound absorption material covered only part of the wall (i.e., 30% of the area of conical and vertical wall). The effect of such sound absorption material was predicted by:

• mockup cavity absorption predicted from measured mockup interior reverberation times and then using Sabine equation, or

• a two-layered Thinsulate© layup model, which attaches to the face (i.e., the interior wall surface) of the mockup cavity. The lay-up model was developed based on the results of impedance tube absorption testing. Furthermore, the effect of air absorption, which is notable in high frequencies (> 1 kHz), was also included.

Currently, the mockup only includes the bare pressure shell. The development of a fairly high-fidelity ECLS wall closeout panel was completed in FY’09. Installing the closeout panel into the mockup, updating the mockup acoustic model with the closeout panel, and validating the model with sound pressure measurement in the mockup will be performed.

In addition to the modeling development described above, other significant achievements were made with respect to Orion acoustics work. In particular, the Orion acoustic mockup, built as part of this acoustic modeling project, was used in demonstrations to protect the acoustic requirements (and the resulting Orion crew acoustic environment). Hamilton Sundstrand had indicated that the acoustic requirements were too strict and that they were not going to meet them. This included the continuous noise requirement, and the noise requirement for the Snorkel Fan (used after landing in a contingency situation). The Orion acoustics mockup was used to demonstrate to high level CxP management what the effects of higher noise levels would mean to Orion crews. As a result, a new commitment was made to hold to the acoustic requirements. An Acoustic Noise Control Plan will now be developed, and additional resources are being used to control noise during design of the vehicle. As part of this effort, the Snorkel Fan noise requirement was re-evaluated and updated to ensure adequate crew voice communications during a contingency landing situation.

Bibliography Type: Description: (Last Updated: 08/31/2018) 

Show Cumulative Bibliography Listing
 
 None in FY 2009
Project Title:  Space Craft Internal Acoustic Environment Reduce
Fiscal Year: FY 2007 
Division: Human Research 
Research Discipline/Element:
HRP SHFH:Space Human Factors & Habitability (archival in 2017)
Start Date: 10/02/2006  
End Date: 09/30/2010  
Task Last Updated: 04/28/2009 
Download report in PDF pdf
Principal Investigator/Affiliation:   Allen, Christopher S M.S. / Lockheed-Martin/ NASA Johnson Space Center 
Address:  2101 Nasa Parkway 
Mail Code SF22 
Houston , TX 77058 
Email: christopher.s.allen@nasa.gov 
Phone: 281.483.9710  
Congressional District: 22 
Web:  
Organization Type: INDUSTRY 
Organization Name: Lockheed-Martin/ NASA Johnson Space Center 
Joint Agency:  
Comments:  
Co-Investigator(s)
Affiliation: 
Chu, S. Reynold  Lockheed/NASA Johnson Space Center 
Project Information: 
Responsible Center: NASA JSC 
Grant Monitor: Woolford, Barbara  
Center Contact: 218-483-3701 
barbara.j.woolford@nasa.gov 
Solicitation / Funding Source: Directed Research 
Project Type: GROUND 
Flight Program:  
TechPort: No 
No. of Post Docs:  
No. of PhD Candidates:  
No. of Master's Candidates:  
No. of Bachelor's Candidates:  
No. of PhD Degrees:  
No. of Master's Degrees:  
No. of Bachelor's Degrees:  
Human Research Program Elements: (1) SHFH:Space Human Factors & Habitability (archival in 2017)
Human Research Program Risks: (1) Hab:Risk of an Incompatible Vehicle/Habitat Design
Human Research Program Gaps: (1) SHFE-HAB-01:What validated acoustic model can predict the effects of structures, materials, crew and equipment on the acoustic environment of a spacecraft or habitat? (CLOSED, per IRP Rev F)
Task Description: Acoustic modeling can be used to identify key noise sources, determine/analyze sub-allocated requirements, keep track of the accumulation of minor noise sources, and to predict vehicle noise levels at various stages in the development, first with estimates of noise sources, later with experimental data. Bench testing of isolated systems alone is not sufficient as the installation effects are often not known. Acoustic modeling will be used to determine installation effects, reverberation (room geometry) effects, and will be used to identify propagation paths and possible noise controls, as well as develop an understanding of the resulting acoustic levels in the composite environment. Finally, acoustic modeling will be used to assist with the development and implementation of spaceflight acoustic materials and to predict their effectiveness including sound containment, absorption and vibration isolation. Prior to this project, NASA did not have institutional acoustic modeling capability in regards to space flight vehicles. Through this project, acoustic modeling capability is being developed for application to the Cx Program and its new spaceflight vehicles to ensure a sufficiently quiet environment in which the astronaut crews can work and live.

In general, modern acoustic modeling techniques such as Statistical Energy Analysis (SEA), Ray-tracing techniques, and Finite Element Methods have been used effectively to reduce interior noise in automotive, aircraft, and some spacecraft designs. Each method has its own strengths depending on the type of noise being modeled and the assumptions used, but it is clear that these methods have been effective; automotive and aircraft noise levels have been substantially reduced in recent years. Also, the continued development, current sophistication, and rising sales of off-the-shelf acoustic modeling software are indicative of their applicability and success, otherwise the companies that build automobiles and aircraft would not purchase these. See reference 1 for a recent article describing the state of the art in acoustic modeling capabilities, including off-the-shelf acoustic modeling software tools.

The objective of this project will be to develop an acoustic modeling capability, based on off-the-shelf software, to be used as a tool for oversight of the future manned Constellation vehicles to ensure compliance with acoustic requirements and thus provide a safe and habitable acoustic environment for the crews. During FY’07, the project’s first year, this project:

1. Determined the acoustic modeling requirements for Constellation vehicles, in terms of frequency range, source type, and model type, and leased an off-the-shelf software package that is well-suited for the modeling task.

2. Developed a simple-geometry acoustic model and validated the model using a physical mockup and acoustic measurements. Tools for modeling the effects of absorptive wall treatments and the resulting reverberation environment were developed as part of this work. Limitations of the modeling technique were also investigated and documented.

Research Impact/Earth Benefits: 0

Task Progress & Bibliography Information FY2007 
Task Progress: New project for FY2007.

Bibliography Type: Description: (Last Updated: 08/31/2018) 

Show Cumulative Bibliography Listing
 
 None in FY 2007