Concept: Architectural acoustics
- Proceedings of the National Academy of Sciences of the United States of America
- Published almost 7 years ago
Imagine that you are blindfolded inside an unknown room. You snap your fingers and listen to the room’s response. Can you hear the shape of the room? Some people can do it naturally, but can we design computer algorithms that hear rooms? We show how to compute the shape of a convex polyhedral room from its response to a known sound, recorded by a few microphones. Geometric relationships between the arrival times of echoes enable us to “blindfoldedly” estimate the room geometry. This is achieved by exploiting the properties of Euclidean distance matrices. Furthermore, we show that under mild conditions, first-order echoes provide a unique description of convex polyhedral rooms. Our algorithm starts from the recorded impulse responses and proceeds by learning the correct assignment of echoes to walls. In contrast to earlier methods, the proposed algorithm reconstructs the full 3D geometry of the room from a single sound emission, and with an arbitrary geometry of the microphone array. As long as the microphones can hear the echoes, we can position them as we want. Besides answering a basic question about the inverse problem of room acoustics, our results find applications in areas such as architectural acoustics, indoor localization, virtual reality, and audio forensics.
There is currently no ASTM method for field measurement of the acoustical noise isolation specific to doors. Measurement of the overall noise reduction of the composite wall/door assembly or the Apparent Sound Transmission Class of the door can be attempted using the methods in ASTM E336, but these methods are not well suited to measuring doors. Doors typically have poorly defined source and receiving rooms, such as long and narrow corridors, stairwells, or outdoor spaces, which often do not meet the room requirements of ASTM E336. The sound fields are rarely diffuse, and the measurement locations are not well defined in the ASTM standard. An alternative insertion loss method (i.e., a comparison of the sound pressure levels with the door open and closed) was developed by MJM Acoustical Consultants (Michel Morin, “Research project on the noise isolation provided by access doors in multi-dwelling buildings,” 1993), and a draft ASTM standard has been developed based on this method. A laboratory testing program has been designed evaluate the proposed method and investigate variations in the test method. The results of the laboratory testing program are presented.
We present a versatile and very low-power traveling SAW microfluidic sorting device able to displace and separate particles of different diameter in aqueous suspension; the travelling wave propagates through the fluid bulk and diffuses via a Schröder diffuser, adapted from its typical use in concert hall acoustics to be the smallest such diffuser to be suitable for microfluidics. The effective operating power range is two to three orders of magnitude less than current SAW devices, uniquely eliminating the need for amplifiers, and by using traveling waves to impart forces directly upon suspended microparticles, they can be separated by size.
Modeling sound transmission among acoustic media through mixed separations, consisting of both rigid/flexible structures with apertures, is a challenging task. The coexistence of both structural and acoustic transmission paths through the same coupling surface adds system complexities, hampering the use of existing sub-structuring modeling techniques when the system configuration becomes complex. In the present work, a virtual panel treatment is proposed to model thin apertures involved in such complex vibroacoustic systems. The proposed virtual panel considers an aperture as an equivalent structural component, which can be integrated with the solid/flexible structure to form a unified compound interface. This allows handling the entire compound interface as a pure structural element, thus providing an efficient and versatile tool to tackle system complexities when using sub-structuring techniques. The accuracy and convergence of the method are investigated and validated, and the effective thickness range allowing for the virtual panel treatments is determined. The capability and the flexibility of the proposed formulation are demonstrated through several numerical examples, with underlying physics being explored.
Electronic sound masking, when properly implemented, can be an effective tool for introducing background noise in occupied spaces, which is a key factor of speech privacy. Mechanical ventilation systems generally cannot be relied upon to provide the consistent and appropriate levels of background noise that sound masking systems are capable of, and this is even more the case with variable-air-volume systems and several emerging (or re-emerging) technologies such as natural ventilation, underfloor air distribution, and chilled beams. However, despite general industry consensus of what constitutes appropriate levels of background noise, striking discrepancies in acoustic performance have been observed for several recent sound masking installations, thus defeating the original objectives for such a system. Fortunately, such issues can be avoided if design efforts account for limitations of both the sound masking system and acoustics of the space, clear performance requirements are established, and the system is properly adjusted and balanced prior to occupancy. Through case studies, this paper seeks through to illustrate the need for a guided approach toward achieving successful outcomes while also highlighting the broader range of issues involved with speech privacy.
R. Selands is an experienced restauranteur with an understanding of the importance of controlling excess sound, as was his architect from the Netherlands. When designing a new restaurant in Sacramento called Ella, acoustics was an important item. Both sound from the HVAC system and patron noise were evaluated. Acoustical treatment of patron noise had to fit in with the aesthetic plan by the architect. HVAC sound was controlled using specific wall and floor/ceiling design and spring isolation. The result was very successful with continuous compliments from patrons. Some issues still exist where a decision was made to not use acoustical treatment. When designing a new market and café, acoustics was not high on the list until the day the facility was opened. Within three days, calls were made requesting assistance to reduce or eliminate excess sound because of complaints from patrons. Site visits, limited field tests, and drawings were used to evaluate the architectural acoustics. Options were provided to modify room finishes to reduce the reverberation time within the space. The most difficult task was modifying the tin-type ceiling to allow sound absorptive material to be placed above.
Many studies have been conducted over the years to explore speech in rooms and its intelligibility to listeners. Speech accommodation by talkers is another developing field in speech and architectural acoustics. In some occupations, a talker’s voice is used nearly continuously throughout the workday. Acoustical conditions in the workplace can significantly affect vocal effort and the health and longevity of the vocal folds. Experimental resources are needed to better understand these conditions and how they may be optimized for the well-being of talkers. The present study investigates the range of acoustical conditions that may be established in a small variable-acoustics chamber for this type of research. The chamber is characterized using many pertinent room-acoustics parameters. Volunteers read passages in the chamber with no visual cues to impact their perception of its changing acoustical treatments. Various measurements were made to establish relationships between the room conditions and vocal efforts.
The Technical Committee on Architectural Acoustics (TCAA) is a Registered Provider in the American Institute of Architects (AIA) Continuing Education System (CES). The TCAA has developed a standardized introductory short course for architects, called “Architectural Acoustics.” An architect can earn one continuing education unit (CEU) by attending this short course, if it is presented by a qualified member of TCAA. The course covers topics in sound isolation, mechanical system noise control, finish treatments, and implementation of quality acoustical spaces. This paper will cover the course material in order to prepare and qualify potential presenters. In order to qualify as an authorized presenter for this AIA/CES short course, attendance at this special session and membership in TCAA are required.
The Technical Committee on Architectural Acoustics (TCAA) is a Registered Provider in the American Institute of Architects (AIA) Continuing Education System (CES). The TCAA has developed a standardized introductory short course for architects called “Architectural Acoustics,” for which attendees can earn one continuing education unit (CEU). This paper will cover the administrative requirements of the AIA/CES, to prepare potential presenters. These requirements include the proper handling of paperwork so that AIA members may receive credit for the course. The manner in which the course is given is also dictated by AIA requirements. TCAA membership and attendance at this workshop are required to qualify as an authorized presenter for this AIA/CES short course. Of course, anyone is free to register with the AIA to provide their own CEU program. However, the advantages of participating in this program are that the TCAA short course is already prepared, it is pre-approved by the AIA, and the registration fees are paid by the Acoustical Society of America.
When ASA members discovered that typical American classrooms were too noisy or reverberant for serious learning in 1988 they began a successful grassroots movement to fix them. By 2002, ASA volunteers produced the first-ever ANSI standard for classroom acoustics. The effort was led by ASA’s TCAA and supported by three other TCs, the S12 Standards Committee, courageous ASA staffers, and elected officers. ANSI Standard S12.60 was adopted fully or partly by school districts, states, and architectural authorities including the Green Building Council. Classroom acoustics research reporting remains active at ASA meetings. We show how this standard helps to make a better world. The new fields of archaeoacoustics and historical acoustics are “hot”. They employ scientific acoustics to study the past. Their novel hypotheses and discoveries attract young investigators to acoustical careers. Sound was more important in the quiet ancient world. Many are fascinated by the 1988 discovery of strong correlation between the locations of Paleolithic cave paintings and cave resonance. Why? A pyramid at Chichen Itza, Mexico, chirps like a bird revered in Mesoamerican cultures. The chirp is explained by applying the convolution theorem to pyramid architecture. Was it intentionally designed? Other archaeoacoustic and historical acoustic examples are addressed.