David Lubman

David Lubman
DL Acoustics · Principal Consultant

B.S., M.S., EE.

About

73
Publications
8,398
Reads
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249
Citations
Education
September 1962 - June 2020
University of California, Los Angeles
Field of study
  • Electrical Engineering
September 1960 - June 1962
University of Southern California
Field of study
  • Electrical Engineering
June 1955 - June 1960
Illinois Institute of Technology
Field of study
  • Electrical Engineering

Publications

Publications (73)
Article
In 1988, two investigators (Iegor Reznikoff and Michel Dauvois) reported a connection between the local density of cave paintings and local sonic “resonance” in three French Paleolithic painted caves. Archaeologist Chris Scarre summarized their findings in a brief article that drew much attention (Painting by Resonance, Nature 338 [1989]: 382). Sca...
Article
Did human consciousness change in the transition from the Paleolithic to the Neolithic era? Paleolithic humans lived with nature in small isolated groups of perhaps 30 to 150 people. For survival, Paleolithic hunter gatherers focused their auditory attention on recognizing emerging opportunities and threats. Consequently, Paleolithics were very att...
Article
Scitation is the online home of leading journals and conference proceedings from AIP Publishing and AIP Member Societies
Article
On my first visit to the ancient Maya ceremonial city of Chichen Itza in 1998, I discovered an amazing sonic phenomenon at a limestone pyramid known as the temple of Kukulkan. This four-sided 30 m high pyramid resides in a large open plaza with no nearby structures to produce echoes. But clap your hands at the pyramid and you hear a brief chirped e...
Conference Paper
Full-text available
Article
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 C...
Conference Paper
Full-text available
A "whispering gallery" (WG) at the Great Ballcourt (GBC) was first reported during its excavation in the 1920s by the storied American archaeologist Silvanus Morley (1883-1948), Director of Carnegie Institution's Chichen Itza project. In a 1925 National Geographic's article he wrote: "Standing in this temple one can speak in a low voice &...
Article
This introductory paper provides an overview of the papers in this session. It showcases important findings of the UK's Essex Study by David Canning & Adrian James (2012) which confirms large listening benefits for reducing reverberation times (RT) to 0.4 sec or less. The Essex study also found a marked drop in LA90 for occupied classrooms when RT...
Conference Paper
Recent findings at Chichen Itza, Mexico suggest that its ancient builders were skilled theatrical sound designers who engineered sound for mind manipulation. Sound effects discovered so far seem uniquely appropriate for each monument and may be intentional designs. At the pyramid of Kukulkan (PK), echoes of handclaps are transformed into chirps of...
Article
Archaeoacoustics adds value when it solves problems that stump archaeologists. At the spring equinox, a mysterious zigzag shadow creeps down a staircase balustrade at the temple of Kukulkan. The shadow represents the Mesoamerican plumed serpent god Kukulkan-or Quetzalcoatl-descending from the heavens. Is that famous shadow accident or design? Despi...
Article
ANSI standard S12.60 requires that background noise not exceed 35 dBA in unoccupied lecture classrooms. Despite the strong and broad research basis for ANSI's 35-dBA requirement, some classroom noise guidelines permit 45 dBA (notably California Collaborative for High Performance Schools and Leadership in Energy and Environmental Design). How did th...
Article
Whispering archways are whispering galleries. They are sometimes found around smooth arches, doorways, and even bridges. Persons positioned on opposite sides of a whispering arch communicate privately by whispering into the arch. In that way they function as private and even intimate soundscapes. Some whispering arches that have stood for centuries...
Article
Highly beneficial noise level reductions of 5–10 dB are reported in occupied classrooms equipped with highly sound absorbing ceilings. The incremental cost for such ceilings is nominal. These “Lombard effect” benefits apply to small classrooms with very low reverberation times (0.5 s or less) which is less than the 0.6‐s maximum specified in ANSI S...
Article
Paleolithic artists were surely impressed by the acoustical properties of their cave dwellings. Since many inhabited caves and grottoes were highly reverberant, it is compelling to speculate that cave acoustics importantly influenced ancient artists. One imaginative suggestion is that Paleolithic artists intentionally chose the most resonant locati...
Article
Full-text available
In May 2008, the U.S. Green Building Council (USGBC) released an updated acoustics prerequisite and credit for inclusion in the Leadership in Energy and Environmental Design for Schools 2009 Rating System. Guidance for the update was provided to the USGBC by the four acousticians in the Indoor Environmental Quality Technical Advisory Group, which f...
Article
Sound field amplifiers continue to be aggressively promoted for mainstream classrooms. Studies showing improved academic achievement with sound field systems mislead by not revealing that the subject classrooms were excessively noisy. Sound field is a band-aid solution for noisy classrooms. Surely, quiet classrooms and natural, unstrained voices im...
Article
Classrooms require adequate sound absorption to establish appropriate environments for listening and learning. Sound absorbing materials improve the classroom learning environment by reducing reverberation time and by reducing background noise levels. ANSI standard S12.60-2002 provides simple methods for determining the amount of sound absorption n...
Article
Church bells have long communicated important information to the surrounding community, creating a sound neighborhood. The community relied on the sound neighborhood to learn of events such as weddings, births and deaths, impending danger, church services, and the curfew. The bells thus provided communal identity. This paper reviews the sound neigh...
Article
Soundfield (amplification) systems are widely and often aggressively marketed for small classrooms. In June 2006, the Acoustical Society of America (ASA) issued a public position statement on the use of sound amplification in typical small classrooms http:asa.aip.orgamplification.pdf. This paper attempts to explain why the ASA found that soundfield...
Article
Full-text available
Chirped echoes from staircases at the temple of Kukulkan at Chichen Itza have stimulated much interest since first reported at scientific meetings by the author in 1998. Among them are Declercq et al (J. Acoust. Soc. Am. 116, (6) 2004). They correctly observed that the echo depends strongly on the "type" of incident sound, but offered no explanatio...
Article
Modular classrooms are important to American education: About 300,000 modular classrooms are currently in use by public school systems here. Good acoustical conditions for learning are no less vital for students in modular classrooms than stick?built classrooms. In an effort to promote good acoustics in modular classrooms, ANSI S12 Working Group 46...
Article
The ball game has played a central role in Mayan religion and culture for 5000 years. Thousands of ball courts have been discovered. The Great Ball Court (GBC) at Chichen Itza is a late development and is architecturally unique. Two remarkable acoustical features were noticed during excavation in the 1920s, but never explained or interpreted. A whi...
Article
The LEED program for green building certification acknowledges the importance of acoustics in building quality and design, but currently does not provide for specific credits in acoustics other than in the Innovation in Design category. This paper presents an overview of the LEED approach to sustainable design and discusses the design categories fo...
Article
This exercise demonstrates that key requirements of the ANSI S12.60-2002 on classroom acoustics can be met through renovations at modest cost. Free-standing classrooms at two schools in Southern California were successfully renovated. Noise levels were greatly reduced, and now meet requirements of the ANSI standard. A 1950s style bungalow classroom...
Article
Currently, classroom amplifiers are being aggressively advocated as substitutes for good acoustics in small mainstream classrooms. Amplifiers are routinely installed without regard to unoccupied classroom noise levels and reverberation times. Amplifiers are being specified by some school districts as a money-saving alternative to mandating complian...
Article
Unlike the traditional ``sage-on-the-stage'' configuration of many K-12 classrooms, the group learning or ``guide-on-the-side'' configuration does not involve communication between a teacher in front of a seated class of 20 to 30 students. Instead, it can involve, most of the time, communication between the teacher and each of several small groups...
Article
For centuries, the sound of ringing church bells has given communities a sense of identity. Church bells have long been used to announce significant events to the community, such as births and deaths, to warn of impending danger, to call the faithful to church and to announce the curfew. This paper focuses on one prominent example of a sound commun...
Article
England’s Chester Cathedral (Anglican) contains a shrine to its patron saint, St. Werburgh, a 7th century Saxon princess of Mercia who became a nun and abbess. The 8th or 9th century shrine is far older than the 16th century cathedral. The shrine was enlarged around 1340, apparently because of its popularity as a place of pilgrimage and reported mi...
Article
Anticipating increased enrollment of children with cochlear implants, the Riverside County Office of Education undertook the acoustical renovation of two portable classrooms in California’s Riverside County: Wildomar Elementary School in Wildomar and Katherine Finchy Elementary School in Palm Springs. The aim was to improve the acoustical environme...
Article
Full-text available
The new standard for classroom acoustics (ANSI S12.60-2002) has generated much interest - and some anxiety in the school planning and design community. The standard is not mandatory but can be adopted voluntarily by schools or school districts. The standard specifies maximum noise levels and reverberation times in unoccupied classrooms, and minimum...
Article
This article outlines the rationale and steps leading to the approval of the first American standard for acceptable acoustics in a classroom setting. The performance criteria for evaluating conformance with the standard are presented, as is a brief overview of the design criteria that can be used in formulation and construction of classrooms with g...
Article
The ANSI Standard on classroom acoustics, S12.60‐2002, has the potential to greatly improve the quality and accessibility of public education. To realize its potential the standard must be put to use. The standard is now voluntary unless it is adopted by a state or school district or is incorporated into individual school construction bidding docum...
Article
Building code sound insulation standards are health measures intended to protect people from excessive noise. In the USA, minimum values for Field Sound Transmission Loss (FSTC), and Field Impact Insulation Class (FIIC) are widely used to rate noise insulation between adjacent condominiums. Current American Society for Testing and Materials (ASTM)...
Article
The soundscapes of classroom and play areas influence children's behavior and learning. For example, the sustained high noise levels of shouting children frequently reported in day care centers are averse to behavior, learning, and teaching. To some extent this Lombard effect, or reflex to the reverberant buildup of room noise, can be tamed by gene...
Article
A cache of 20 Strombus shell trumpets was excavated in 2001 from an underground gallery at Chavin de Huantar, the type site of the Peruvian Early Horizon period (ca. 1200 to 400 B.C.). Strombus shell usage stretches from antiquity to present day Peru, with the trumpet function showing remarkable continuity. Soon after their discovery, a dozen of th...
Article
Chichen Itza dominated the early postclassic Maya world, ca. 900-1200 C.E. Two of its colossal monuments, the Great Ball Court and the temple of Kukulkan, reflect the sophisticated, hybrid culture of a Mexicanized Maya civilization. The architecture seems intended for ceremony and ritual drama. Deducing ritual practices will advance the understandi...
Article
A draft ANSI (American National Standards Institute) Standard for classroom acoustics will be submitted for approval this year. It is believed that adopting this Standard will result in a more inclusive and effective education system. Although eliminating acoustical barriers benefits everyone, young children and persons with hearing, language, spee...
Article
Acoustical communication is a vital element in the co‐evolution of worship space architecture and liturgy. Acoustical communication in worship spaces is bound by scientific verities. Information theory holds that for any communication channel there exists an optimum coding of transmitted information. Speech and music are alternative informational c...
Article
The International‐INCE General Assembly approved Technical Initiative ♯4 in December 1999. The initiative creates an internationally coordinated program intended to assist participating nations with engineering issues associated with achieving satisfactory acoustics in learning spaces. Representatives of various acoustical societies were appointed...
Article
Good acoustics is an indispensable requirement for verbal learning, and therefore vital to all knowledge?based societies. The World Health Organization has identified the basic acoustical requirements for verbal learning spaces (Guidelines for Community Noise, April 1999). Some nations are well advanced in meeting these requirements while others ma...
Article
Buzz Towne’s idealism sparked ASA’s current activities to improve classroom acoustics, including ANSI S12 WG43’s activity to produce an American standard for classroom acoustics. But idealism alone may not suffice to realize the reforms Buzz sought. It will help if advocates can show that good classroom acoustics are a good investment for community...
Article
Handclaps evoke impressive chirped echoes from the unusually narrow limestone staircases of the Mayan pyramid at Chichén Itzá, located in Mexico’s northern Yucatan. This highly conspicuous acoustical feature, apparently ignored in the archaeological literature, may provide important clues to Mayan cultural practices of the time. Inspection and ray...
Article
Architectural guidelines and standards for classroom acoustics are needed for the general population, as well as for special groupings such as hearing? and learning?disabled students, non?native listeners and talkers, and teachers with mild?to?severe hearing handicaps. Without specific guidelines, economic considerations or ignorance may tempt arch...
Article
The understanding of room reverberation has advanced notably in recent decades owing to the merging of statistical communication theory with room acoustics. New invariants expressed as simple and robust statistical laws govern steady‐state variation of reverberant sound pressure over time, frequency, and space. Much of statistical room acoustics (S...
Article
Co-located pressure and particle motion (PM) hydrophones together with four-channel diversity combiners may be used to recover signals from multipath fading. Multipath fading is important in both shallow and deep water propagation and can be an important source of signal loss. The acoustic field diversity concept arises from the notion of conservat...
Article
A pilot experiment was conducted to compare the assessments of the acoustics of a concert hall made by music critics, musicians, and ??others.?? The experiment, a cooperative effort between the ASA and the Music Critics Association of North America (MCANA), was performed in Dallas, TX at the McDermott concert hall of the Meyerson Symphony Center du...
Article
The predominant problem of the hearing‐impaired individual is speech communication. In noisy and reverberant restaurants where speech communication is difficult to impossible, these individuals cannot enjoy the experience of dining out. This fact was conveyed to the US government during hearings for the Americans with Disabilities Act. A program wa...
Article
Professional music critics often pass judgment on concert hall acoustics in their reviews. Because of the wide circulation given to their reviews, music critics may strongly influence public perceptions of the acoustical merits of concert halls. Surprisingly, no systematic study has been reported comparing critics? acoustical judgments with those o...
Article
Full-text available
Now an IEC Standard, RASTI provides an objective physical method for assessing speech intelligibility under conditions of steady noise and/or reverberation. Continued growth of the technique's usefulness depends in part on four conditions: (a) users' ingenuity and willingness to find appropriate applications and to share results; (b) inst...
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Full-text available
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The recent trend toward mainstreaming the handicapped, implies that acoustical designers must now consider the needs of persons with hearing and visual handicaps. What are these needs, and how can designers meet them? Invited speakers and panelists have been assembled to address these questions. They will review evidence showing that sensorially ha...
Article
Large, high?intensity sonic chambers are planned increasingly for preflight testing of space hardware. Since both capital and operating costs are closely tied to chamber size, planners have a strong incentive to select the smallest chamber size consistent with performance requirements. Current test codes and design practice appear to be inadequate...
Article
Full-text available
The eigenmode and free‐wave models of steady‐state reverberant sound field in rooms are sometimes mistakenly believed to be unrelated representations. These two models are shown to coincide for the case of rectangular rooms, for which the axial, tangential, and oblique modes can be decomposed into two, four and eight travelling plane waves, respect...
Article
Traversing microphone (TM) spectroscopy provides a rapid and sensitive means for assessing sound diffusion in rooms. TM spectra are power spectra obtained at the terminals of a small microphone during its traverse through a room at constant speed. The TM spectral shape is a sensitive indicator of the degree of directional diffusion. If the field is...
Article
It is acknowledged that there are errors in Eq. A10, together with Eqs. A4 and A5 of our paper [J. Acoust. Sco. Am. 53 650–659 (1973)]. The advantages of the Corrington method of solution, in certain circumstances, are discussed.
Article
Full-text available
A minimum distance between source and microphone is necessary for practical measurements of reverberant sound power and sound transmission loss. This is intended to limit error due to contamination by the direct field. An experimental/graphical procedure for its determination is prescribed in two important measurement Standards (ANSI S1.21‐1972 and...
Article
The effectiveness of spatial averaging in an ideal diffuse field is examined, with intended application to pure‐tone reverberant sound powermeasurement. A theoretical measure of spatial averaging effectiveness is proposed, based on the variance of the spatial average, which is determined analytically from the shape and size of the intended path. Th...
Article
Diffuseness of reverberant sound is a sine qua non for accurate reverberation roommeasurement of sound absorption, power, and transmission loss. Most authorities regard it as important for the concert hall as well. And yet, technique for the measurement of diffuseness is not well developed. In this connection, the recently proposed technique of TM...
Article
Determination of sound power in a reverberation room is subject to a random error whose size can be estimated and controlled by the knowledgeable laboratory manager. Under ideal measurement conditions the random error can be expressed as a product of three factors: a frequency‐averaging factor governed by spectrum shape and room reverberation time,...
Article
A small microphone traversing the sound field in a room will encounter spatial variations of sound pressure. Residing in the time statistics of the microphone signal is information about the space statistics of the sound field?information which may be found from a spectral analysis of the microphone signal. For example, the theoretical traversing m...
Article
Research on the effects of aircraft noise on children's learning suggests that aircraft noise can interfere with learning in the following areas: reading, motivation, language and speech acquisition, and memory. The strongest findings to date are in the area of reading, where more than 20 studies have shown that children in noise impact zones are n...
Article
Estimation of mean pressure squared in a reverberation room embodies averages over time, frequency, and space. The benefits of space averaging may be expressed by a number Neq the equivalent number of uncorrelated samples (degrees of freedom) resulting from space averaging. The variance of the estimated mean pressure squared is that due to frequenc...
Article
To measure sound power in a reverberation room, we need to estimate the space-time average of squared sound pressure. While the time average usually presents no special problem, the space average may cause difficulties, particularly for acoustic signals having pure-tone or extremely narrow-band spectra. The space average is subject to a random erro...
Article
To measure sound power in a reverberation room, we need to estimate the space‐time average of squared sound pressure. While the time average usually presents no special problem, the space average may, particularly for acoustic signals having pure‐tone or extremely narrow‐band spectra. The space average is subject to a random error due to finite sam...
Article
Full-text available
The measurement of sound power in a reverberant room makes use of the level corresponding to room?averaged sound intensity, 10 log ?I?. But when measurements are in decibels?as is usually the case?it is computationally simpler to employ the room?averaged level ?10 log I?. This substitution leads to a bias in the direction of underestimating the tru...

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