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Selected Works

Room acoustics

Articles 1 - 12 of 12

Full-Text Articles in Mechanical Engineering

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 Jun 2014

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

Lily M Wang

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 ...


Binaural Room Impulse Response Database Acquired From A Variable Acoustics Classroom, Zhao Peng, Siu Kit Lau, Lily M. Wang, Sean Browne, Kenneth P. Roy Jun 2014

Binaural Room Impulse Response Database Acquired From A Variable Acoustics Classroom, Zhao Peng, Siu Kit Lau, Lily M. Wang, Sean Browne, Kenneth P. Roy

Lily M Wang

Room measurements were conducted in a variable acoustics classroom mockup space (epod) at Armstrong World Industries in Lancaster, Pennsylvania, USA. Binaural room impulse responses were measured in the epod using a head and torso simulator. Five reverberation time (RT) scenarios were achieved with various combinations of absorptive wall panels and acoustical ceiling tile. These provided a range of mid-frequency RTs from 0.4 to 1.1 seconds. Three of the five RT scenarios were achieved using two different material configurations to also consider material location effects. For each of the eight material configurations, two student-teacher orientations were tested. One orientation ...


Investigations Of Multi-Channel Auralization Technique For Various Orchestra Arrangements, With Phase-Shifted String Sections, Michelle C Vigeant, Lily M. Wang Jun 2014

Investigations Of Multi-Channel Auralization Technique For Various Orchestra Arrangements, With Phase-Shifted String Sections, Michelle C Vigeant, Lily M. Wang

Lily M Wang

An orchestra can be simulated in room acoustics computer modelling using a variety of methods, ranging from a single omni-directional source to individual sources of all instruments. This study utilizes the method of individual sources for each instrument, but with reduced source representation for the string sections. The anechoic recordings used in this investigation are five-channel recordings, which capture the source directivity of the individual instruments. For each string section, the individual anechoic recordings were phase shifted several times, up to 23 ms, and combined to create a single recording for use in the simulations. An orchestra was simulated in ...


The Effects Of Simple Coupled Volume Geometry On The Objective And Subjective Results From Nonexponential Decay, David T. Bradley, Lily M. Wang Jun 2014

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

Lily M Wang

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 the three variables ...


Room Acoustics In Coupled Volume Spaces, David T. Bradley, Lily M. Wang Jun 2014

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

Lily M Wang

The study of sound in the built environment is finding more awareness in the 21st 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 sonically ...


Effects Of Acoustic Environments On Speech Comprehension By Native-English-Speaking Listeners, Zhao Peng, Lily M. Wang, Siu Kit Lau Jun 2014

Effects Of Acoustic Environments On Speech Comprehension By Native-English-Speaking Listeners, Zhao Peng, Lily M. Wang, Siu Kit Lau

Lily M Wang

This study investigates the effects of acoustic conditions on speech comprehension, rather than speech intelligibility as often reported in existing literature. Sets of 15-minute-long listening comprehension tests were developed based on the format of the Test of English for International Communication (TOEIC). Each test set includes four types of tasks: matching aural phrases to photographs, selecting appropriate responses to aural questions, and answering questions after listening to conversations (between two talkers) and talks (single talker). Within the Nebraska acoustics test chamber, native-English-speaking participants are asked to perform these tests under 15 acoustic conditions, from combinations of three background noise levels ...


Investigations Of Multi-Channel Auralization Technique For Solo Instruments And Orchestra, Michelle C Vigeant, Lily M. Wang, Jens Holger Rindel Jun 2014

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

Lily M Wang

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 ...


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 Jun 2014

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

Lily M Wang

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 ...


A Review Of Diffuse Reflections In Architectural Acoustics, Jonathan Rathsam, Lily M. Wang Jun 2014

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

Lily M Wang

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.


Room Acoustics Computer Modeling: Study Of The Effect Of Source Directivity On Auralizations, Michelle C Vigeant, Lily M. Wang, Jens Holger Rindel Jun 2014

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

Lily M Wang

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 ...


Objective And Subjective Evaluation Of The Use Of Directional Sound Sources In Auralizations, Lily M. Wang, Michelle C Vigeant Jun 2014

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

Lily M Wang

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 ...


Relationships Between Unoccupied Classroom Acoustical Conditions And Elementary Student Achievement Measured In Eastern Nebraska, Lauren M Ronsse, Lily M. Wang Jun 2014

Relationships Between Unoccupied Classroom Acoustical Conditions And Elementary Student Achievement Measured In Eastern Nebraska, Lauren M Ronsse, Lily M. Wang

Lily M Wang

Building standards recommend maximum background noise levels (BNL) and reverberation times (RT) for unoccupied classrooms. However, existing research does not show a consistent correlation between these parameters and student achievement. Through in situ testing, this research seeks to determine what acoustical conditions should be attained in elementary schools for students to meet educational goals. Acoustical measurements were conducted in a Nebraska public school system and correlated to achievement scores from students in the surveyed classrooms. Unoccupied BNLs and RTs were gathered in 34 third and 33 fifth-grade classrooms. Additionally, binaural room impulse response measurements were gathered in a subset of ...