Architecture Commons^™

Investigations Of Multi-Channel Auralization Technique For Solo Instruments And Orchestra, Michelle C Vigeant, Lily M. Wang, Jens Holger Rindel

Durham School of Architectural Engineering and Construction: Faculty Publications

Computer modeling of room acoustics is a useful tool in the design of acoustically sensitive spaces and an important outcome from these programs is auralizations. This study examined the perceived changes in realism and source width when listening to multi-channel auralizations compared to single channel auralizations for both solo instruments and a full orchestra. The first experiment, which examined subjective judgments of auralizations made from solo instruments, showed that perceived realism increased as the number of channels was increased from one to four to thirteen, while the relationship between source width and number of channels was less clear. In the …

Scattered Responses From Suspended Reflector Panels With Rounded Edges, Jonathan Rathsam, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

Sound reflections from most finite surfaces, such as overhead reflector panels, include a component known as edge diffraction. Edge diffraction is the scattered energy required to maintain a continuous sound field despite the discontinuity in acoustical impedance presented by the scatterer. Edge diffraction can interfere with primary scattered energy to produce comb filtering at receiver locations. Several decades ago, the effect of changing the edge profile of loudspeaker boxes was investigated with the goal of producing a smoother frequency response. By rounding the edges of loudspeaker boxes, the edge diffraction could be decreased noticeably [H. F. Olson, J. Aud. Eng. …

Reflector Responses: A Comparison Between Odeon’S Modified Ray Tracing Algorithm And A Filtered Boundary Element Method Model, Jonathan Rathsam, Lily M. Wang, Jens Holger Rindel, Claus Lynge Christensen

Durham School of Architectural Engineering and Construction: Faculty Publications

The biggest challenge for geometrical room acoustic computer models is to capture complex wave phenomena while maintaining the low computational load of the ray tracing algorithm. Special corrections must be added to the ray tracing algorithm to account for wave phenomena such as edge diffraction, which are ignored by classical geometrical acoustics. ODEON, a well-known geometrical computer model, is in the process of upgrading its ray tracing and scattering algorithm. The new algorithm allows users to specify transmission through reflector panel arrays. To aid in the development of ODEON’s new algorithm, its predictions are compared with predictions from a boundary …

Effects Of Changing The Amount Of Absorption In A Computer Model Of Queen’S Hall, Copenhagen, Denmark, Michelle C Vigeant, Lily M. Wang, Jens Holger Rindel

Durham School of Architectural Engineering and Construction: Faculty Publications

Room acoustics modelling and auralizations are very useful tools in the design of acoustically sensitive spaces. One area of improvement for auralizations is the method of modelling the source directivity. A new method to incorporate source directivity is multi-channel auralizations. This study first evaluates the objective effects of using four and thirteen channel impulse responses in an ODEON model of Queen’s Hall, where the actual variable absorption is changed within the model. Analyses of the results reveal great differences in the objective parameters of reverberation time and sound pressure level across each channel’s impulse response. Subjective studies were then conducted …

Appropriate Characterization Of Background Noise Levels In The Workplace, Erica E. Bowden, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

Overall loudness is not the only quality of indoor background noise that affects occupants. The distribution of noise across frequency (pitch), whether or not the noise contains tones, and whether or not the noise changes over time must also be considered. There are several indoor noise criteria systems available to quantify the background noise in rooms, but many of them do not account for these factors. These systems are commonly used by architects and engineers, and often incorporated into manufacturer’s data, design guides, and standards. There is much debate over which of the criteria systems best reflect how occupants will …

Room Acoustics In Coupled Volume Spaces, David T. Bradley, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

The study of sound in the built environment is finding more awareness in the 21^st century. As this awareness has increased, and as computing power has grown, the method of computer modeling for studying room acoustics in such settings as classrooms, offices, and performances spaces has taken great strides in recent years. Of particular interest has been the study of the coupled volume space due to its unique ability to provide contrasting acoustical phenomenon. A coupled volume room is generally defined as a space consisting of a large main volume containing high levels of sound absorption connected through small …

Effects Of Noise On Productivity: Does Performance Decrease Over Time?, Jessica Errett, Erica Eileen Bowden, Marc Choiniere, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

Most people at one time or another have found themselves irritated or distracted by the background noise in a building. The irritation might have resulted in minor aggravation or may have been dramatic enough to hinder their work. This leads us to ask whether occupants are increasingly aggravated by noise the longer they are exposed to it, or if they naturally habituate to their acoustic environment. In an effort to answer this question, a study was completed in the “Indoor Environment Lab” at the University of Nebraska. This lab resembles a typical office and was specially constructed to be acoustically …

A Review Of Diffuse Reflections In Architectural Acoustics, Jonathan Rathsam, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

Diffuse reflections have received increasing attention in architectural acoustics over the past quarter century. The term diffuse refers to non-specular directions. This paper identifies three mechanisms that cause diffuse reflections. Practitioners have found that changing specular reflections into diffuse reflections can reduce noise and echoes both indoors and outdoors. Developers of acoustical modeling software have also found that modeling diffuse in additional to specular reflections produces more accurate predictions. The final portion of this paper presents results for a study of scattering coefficients in acoustical modeling software.

Measuring Sound Power In Ducted Heating, Ventilating, And Air-Conditioning (Hvac) Systems For Use In Verifying Acoustical Prediction Methods, Steven R. Ryherd, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

This paper discusses issues regarding in-situ methods of obtaining sound power at a point in a heating, ventilating and air-conditioning (HVAC) duct system. Such a method is being used as part of a larger investigation on acoustical prediction methods to allow for comparison of measured data to results from attenuation predictions of individual duct elements, such as elbows or dampers. Sound propagation in HVAC duct work is complex. Any measurements of sound energy in the duct must address the characteristics of sound propagation in ducts, end reflections, and air turbulence. Investigations are being conducted to understand the extents to which …

Room Acoustics Computer Modeling: Study Of The Effect Of Source Directivity On Auralizations, Michelle C Vigeant, Lily M. Wang, Jens Holger Rindel

Durham School of Architectural Engineering and Construction: Faculty Publications

Auralizations are very useful in the design of performing arts spaces, where auralization is the process of rendering audible the sound field in a space, in such a way as to simulate the binaural listening experience at a given position in the modeled space. One of the fundamental modeling inputs to create auralizations is the source directivity. Standard methods involve inputting the measured source directivity, calculating the impulse response and convolving it with a single channel anechoic recording. An initial study was conducted using this method and the results showed significant differences in reverberation time and clarity index when using …

The Effects Of Simple Coupled Volume Geometry On The Objective And Subjective Results From Nonexponential Decay, David T. Bradley, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

This project focuses on the individual and interactive acoustic effects of three architectural parameters on the double slope profile from a simple coupled volume system created in the computer modeling program ODEON. The three variables studied are the volume ratio between the main and secondary spaces, the absorption ratio between the two spaces, and aperture size. The resulting energy decay profiles are analyzed using T₃₀/T₁₅ Coupling Coefficient ratios and Bayesian analysis. Coupling Coefficient results show general trends in the effects of the three architectural parameters that match previous research results and the predominant interactive effect between …

Fume Hood Exhaust Stack System, Mingsheng Liu

Durham School of Architectural Engineering and Construction: Faculty Publications

A fume hood exhaust stack system (10) and method utilize a variable speed fan (24) and an exhaust stack (28) having an adjustable cross-sectional area. Toxic exhaust from one or more fume hoods (12) is conveyed through a header (16) to the fan. The fan forces the exhaust through the exhaust stack, and the exhaust is then discharged into the atmosphere at a sufficient velocity and momentum to ensure that the exhaust reaches an environmentally sound altitude. A variable speed drive (36), programmable controller (34), flow signals (26), and static pressure and total pressure signals (20) are utilized to modulate …

Continuous Commissioning Leading Energy Project Process - An Industry Approach, Mingsheng Liu, Jinrong Wang, Ken Hansen, Ann Selzer

Durham School of Architectural Engineering and Construction: Faculty Publications

Continuous Commissioning (CC^®) is an ongoing process to resolve operating problems, improve comfort, optimize energy use, and identify retrofits for existing commercial and institutional buildings and central plant facilities. This process was initiated in 1992 and formally documented in 1999 by the Energy Research Journal and in 2002 by the Continuous Commissioning Guidebook for Federal Energy Managers. The CC process has been very successful for many public facilities. A significant amount of energy savings has been achieved and documented.

Recently, the authors developed the Continuous Commissioning Leading Energy Project process and demonstrated this process in over a dozen …

Engineering And Software Requirements Of The Automated Building Commissioning Analysis Tool (Abcat), David E. Claridge, Mingsheng Liu, Frank Painter, Gang Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

Disclaimer - 3

Acknowledgements - 4

Engineering Requirements

Software Requirements - 5

Or-05-6-4: Relating Human Productivity And Annoyance To Indoor Noise Criteria Systems: A Low Frequency Analysis, Erica Eileen Bowden, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

A number of indoor noise criteria systems are used to quantify the background noise in a built environment, including Noise Criteria (NC), Balanced Noise Criteria (NCB), Room Criteria (RC), Room Criteria Mark II (RC Mark II), A-weighted Equivalent Sound Pressure Level (L_Aeq), and others. An on-going debate exists in the acoustical community over which criterion is the most appropriate to use in the variety of ambient noise situations encountered. In an effort to quantitatively support the use of individual criterion, this project subjectively correlates these various criteria with human task performance and perception. Eleven subjects participated in a …

Mechanical Damping System For Structures, Jay A. Puckett, Patrick S. Mcmanus, Homer R. Hamilton Iii

Durham School of Architectural Engineering and Construction: Faculty Publications

A mechanical damping system for a structure is provided. The mechanical damping system comprises a tubular impact frame secured to the structure. A support frame is secured to the structure with the support frame spaced from the impact frame. An elongated member is provided having a first end and a second end. The first end is secured within the support frame and the second end is free from connection and extends into the impact frame. At least one impact mass is secured to the second end of the elongated member, the impact mass movable within and contactable with the impact …

Objective And Subjective Evaluation Of The Use Of Directional Sound Sources In Auralizations, Lily M. Wang, Michelle C Vigeant

Durham School of Architectural Engineering and Construction: Faculty Publications

Omni-directional sources are often used in room acoustic computer simulations, as opposed to directional sources, since measured directivity data are quite limited and difficult to obtain. The purpose of this study is to investigate the objective and subjective significance of adding more complex directivity to the sources used in computer simulations and auralizations. A simple hall was used as the modelled space in the software program ODEON. Three source positions on stage and three receiver audience positions were chosen. Impulse responses (IRs) were calculated for the nine source/receiver combinations, using (a) an omni-directional source, (b) a highly directional source beaming …

Interactions Of Model Detail Level And Scattering Coefficients In Room Acoustic Computer Simulation, Lily M. Wang, Jonathan Rathsam, Steven Ryherd

Durham School of Architectural Engineering and Construction: Faculty Publications

A previous study by the author showed that varying the geometric detail level across a normal range for room acoustic computer modeling has little effect on the results of those computer simulations, if major surfaces in the hall are still constructed accurately. Scattering coefficients were kept constant across all detail levels. If one were using lower levels of detail, though, one might assign different material scattering coefficients to compensate for the less mixing geometry. To study the interaction between model detail level and scattering coefficient selection, three performance spaces in Omaha, Nebraska have been modeled in ODEON at varying levels …

Performance Review Of Indoor Noise Criteria, Lily M. Wang, Erica Eileen Bowden

Durham School of Architectural Engineering and Construction: Faculty Publications

Currently there are a number of indoor noise criteria used to quantify the level of background noise in rooms, including Noise Criteria (NC), Balanced Noise Criteria (NCB), Room Criteria (RC), Room Criteria Mark II (RC Mark II) and others. This paper reviews the pros and cons of each of these and then compares the values measured in existing classrooms in the Omaha area. The authors are in the process of subjectively comparing these various criteria to determine which method best correlates with human perception. The subjective testing methods and preliminary results are discussed.

“Predictive Optimal Control Of Active And Passive Building Thermal Storage Inventory”, Gregor P. Henze, Moncef Krarti

Durham School of Architectural Engineering and Construction: Faculty Publications

Cooling of commercial buildings contributes significantly to the peak demand placed on an electrical utility grid. Time-of-use electricity rates encourage shifting of electrical loads to off-peak periods at night and weekends. Buildings can respond to these pricing signals by shifting cooling-related thermal loads either by precooling the building’s massive structure or the use of active thermal energy storage systems such as ice storage. While these two thermal batteries have been engaged separately in the past, this project investigates the merits of harnessing both storage media concurrently in the context of predictive optimal control.
The analysis, modeling, and simulation research presented …

Implementation Of The Laboratory Air Handling Unit Systems (Lahu), Y. Cui, Mingsheng Liu, K. Conger

Durham School of Architectural Engineering and Construction: Faculty Publications

The LAHU system has been designed, installed, and commissioned in a large university research building. This paper provides detailed information about the demonstration project, including the specific LAHU system mechanical design, optimal airflow control schedules, and measured LAHU energy and indoor air quality (IAQ) performance. The measured energy and IAQ performance are also compared with the conventional operation and theoretical predicated values.

Integrated Chiller System Reduce Building Operation And Maintenance Costs In Cold Climates, N. Sheets, Mingsheng Liu

Durham School of Architectural Engineering and Construction: Faculty Publications

Although water-cooled chillers are more energy efficient than air-cooled chillers, a majority of chilled water systems use air-cooled chillers. In cold weather climates, air-cooled chillers are capable of functioning in low ambient temperatures with few operational concerns, where as water-cooled chiller systems must be equipped to prevent cooling tower freezing. The integrated chiller system attempts to take advantage of each chiller’s strengths and eliminate any cold weather operational concerns. An integrated chiller system includes a cooling tower and air-cooled condenser. During the summer, both the cooling tower and air condenser can be operated. In cold weather, the cooling tower is …

Development Of By-Pass Blending Station System, Mingsheng Liu, D. Barnes, K. Bunz, N. Rosnberry

Durham School of Architectural Engineering and Construction: Faculty Publications

A new building blending station system named by-pass blending station (BBS) has been developed to reduce building pump energy consumption in both district heating and cooling systems. Theoretical investigation demonstrated that the BBS can significantly reduce building pump power for a typical cooling system when constant water flow is maintained in the building side. When differential pressure reset is applied in the building side, more pump energy can be saved. The BBS also reduces the pump size and therefore results in lower initial system cost. A case study was also performed and demonstrated 42% of annual chilled water pump energy …

Improving Building Control And System Operation Through The Continuous Commissioning® Process: A Case Study, Nathan Redmann, Mingsheng Liu

Durham School of Architectural Engineering and Construction: Faculty Publications

Utilization of the Continuous Commissioning^® process is presented in the case of the Consolidated Mission Support Center office building at Travis Air Force Base in Travis, California. The CC^® process was applied to the building in early 2003. The examination of the heating, ventilating, and airconditioning (HVAC) and control systems revealed several areas where considerable improvement could be made, including air handling unit (AHU) operational parameters, terminal box and water loop operation, and Energy Management and Control System (EMCS) functionality. It also aided in the identification of mechanical systems needing repair. The optimization of the HVAC systems and …

Acoustic Communication In Panthera Tigris: A Study Of Tiger Vocalization And Auditory Receptivity, Edward J. Walsh, Lily M. Wang, Douglas L. Armstrong, Thomas Curro, Lee G. Simmons, Joann Mcgee

Durham School of Architectural Engineering and Construction: Faculty Publications

To adults and children alike, tigers are one of the best-known members of the animal kingdom. It may be surprising, then, to learn that we have a lot to discover about their hearing and the acoustics of their vocalizations. To help fill in the gaps in our knowledge, we are in the midst of a study that is focused on the characterization of the vocal properties and hearing capabilities of a subset of surviving tiger subspecies, namely the Siberian, Bengal, Sumatran and the Indochinese tigers. We are hoping that our findings will not only add to a deeper understanding of …

Comparison Of Radiated Power From Structurally Different Violins, Lily M. Wang, Courtney B. Burroughs

Durham School of Architectural Engineering and Construction: Faculty Publications

The acoustic power has been determined from intensity measurements on three structurally different violins: a Scherl and Roth student violin, Hutchins' SUS29S, and Hutchins' mezzo violin SUS 100. While each violin was bowed with an open-frame mechanical bowing machine, the intensity measurements were made by scanning each side of the bowing machine with an intensity probe. One-third octave band sound power levels of the acoustic radiation from each of the three instruments as each of the four open strings is bowed show that the structurally different mezzo violin produces greater power at low frequencies when the lowest (G) string is …

Variable Speed Drive (Vsd) Applications In Dual-Duct Constant Volume Systems, Ik-Seong Joo, Mingsheng Liu, Kirk Conger, Gang Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

Models have been developed for static pressure and potential supply fan energy savings by using variable speed drive (VSD) in dual-duct constant volume systems. Experiments have been performed using a full size dual-duct constant volume system installed in a 68,000 ft² (6,317 m²) office and classroom building. The measured static pressure variations and the energy savings agree with the model projected values. The VSD saves the fan power by as much as 35%, reduces the total airflow by 15%, and decreases the excessive static pressure on the terminal box dampers. This paper presents the systems models, the …

Acoustic Radiation From Bowed Violins, Lily M. Wang, Courtney B. Burroughs

Durham School of Architectural Engineering and Construction: Faculty Publications

Nearfield acoustic holography (NAH) is applied to visualize the acoustic radiation from bowed violins across a frequency range from 294 Hz to 3 kHz. These visualizations are employed to localize regions of acoustic radiation from surfaces of violins. Three violins were tested: a common student instrument by Scherl and Roth; Hutchins violin SUS295, which has been the subject of many previous investigations; and a Hutchins mezzo violin from the Violin Octet set of instruments, which is longer, broader and thinner than a standard instrument. The violins were bowed continuously with an open-frame mechanical bowing machine, while NAH measurements were made …

Motorized Insulated Damper Assembly For Furnace Systems, William Max Kirk, Timothy Wentz

Durham School of Architectural Engineering and Construction: Faculty Publications

A damper unit is provided that is adapted to be positioned in a furnace duct line. The damper unit has a housing which is in communication with a fresh air source and a furnace system. The housing has a damper blade which is moveable between an open position which allows air flow through the housing and a closed position which prevents air flow through the housing. The blade is coupled with a Solenoid so that when the Solenoid is activated the blade is moved to an open position allowing air flow through the housing. Further, a fan is located in …