Leo L. Beranek

Bio: Leo L. Beranek is an academic researcher from BBN Technologies. The author has contributed to research in topics: Noise & Reverberation. The author has an hindex of 28, co-authored 119 publications receiving 5036 citations. Previous affiliations of Leo L. Beranek include Massachusetts Institute of Technology & Harvard University.

Noise and vibration control

Abstract: Who Are We?-A group of mechanical engineers, material scientists, architects, project managers with over 50 years experience, research scientists and manufacturers-We operate a full-service research laboratory for product development, proof-of-performance testing, competitive product testing and fundamental acoustics research in collaboration with leading universities-We offer free engineering design assistance and shop drawings-We offer the widest range of elastomers and standard and custom springs-We offer the lowest elastomer resonant frequency-We offer free predictive TL programs for airborne and vibration noise-We offer new solutions to old and new problems through research and design experience

Noise and vibration control engineering - Principles and applications

Abstract: Preface. Contributors. 1. Basic Acoustical Quantities: Levels and Decibels (Leo L. Beranek). 2. Waves and Impedances (Leo L. Beranek). 3. Data Analysis (Allan G. Piersol). 4. Determination of Sound Power Levels and Directivity of Noise Sources (William W. Lang, George C. Maling, Jr., Matthew A. Nobile, and Jiri Tichy). 5. Outdoor Sound Propagation (Ulrich J. Kurze and Grant S. Anderson). 6. Sound in Small Enclosures (Donald J. Nefske and Shung H. Sung). 7. Sound in Rooms (Murray Hodgson and John Bradley). 8. Sound-Absorbing Materials and Sound Absorbers (Keith Attenborough and Istvan L. Ver). 9. Passive Silencers (M. L. Munjal, Anthony G. Galaitsis and Istvan L. Ver). 10. Sound Generation (Istvan L. Ver). 11. Interaction of Sound Waves with Solid Structures (Istvan L. Ver). 12. Enclosures, Cabins, and Wrappings (Istvan L. Ver). 13. Vibration Isolation (Eric E. Ungar and Jeffrey A. Zapfe). 14. Structural Damping (Eric E. Ungar and Jeffrey A. Zapfe). 15. Noise of Gas Flows (H. D. Baumann and W. B. Coney). 16. Prediction of Machinery Noise (Eric W. Wood and James D. Barnes). 17. Noise Control in Heating, Ventilating, and Air Conditioning Systems (Alan T. Fry and Douglas H. Sturz). 18. Active Control of Noise and Vibration (Ronald Coleman and Paul J. Remington). 19. Damage Risk Criteria for Hearing and Human Body Vibration (Suzanne D. Smith, Charles W. Nixon and Henning E. Von Gierke). 20. Criteria for Noise in Buildings and Communities (Leo L. Beranek). 21. Acoustical Standards for Noise and Vibration Control (Angelo Campanella, Paul Schomer and Laura Ann Wilber). Appendix A. General References. Appendix B. American System of Units. Appendix C. Conversion Factors. Index.

Concert and Opera Halls: How They Sound

Abstract: This illustrated guide examines the acoustical quality of some of the world's most important concert and opera halls and reveals how composers and musicians adapt their art to complement the acoustics of their surroundings. It should be of value to musicians and concert-goers, concert hall managers, recording and audio engineers, and acousticians.

From sensation to cognition.

Abstract: Sensory information undergoes extensive associative elaboration and attentional modulation as it becomes incorporated into the texture of cognition. This process occurs along a core synaptic hierarchy which includes the primary sensory, upstream unimodal, downstream unimodal, heteromodal, paralimbic and limbic zones of the cerebral cortex. Connections from one zone to another are reciprocal and allow higher synaptic levels to exert a feedback (top-down) influence upon earlier levels of processing. Each cortical area provides a nexus for the convergence of afferents and divergence of efferents. The resultant synaptic organization supports parallel as well as serial processing, and allows each sensory event to initiate multiple cognitive and behavioural outcomes. Upstream sectors of unimodal association areas encode basic features of sensation such as colour, motion, form and pitch. More complex contents of sensory experience such as objects, faces, word-forms, spatial locations and sound sequences become encoded within downstream sectors of unimodal areas by groups of coarsely tuned neurons. The highest synaptic levels of sensory-fugal processing are occupied by heteromodal, paralimbic and limbic cortices, collectively known as transmodal areas. The unique role of these areas is to bind multiple unimodal and other transmodal areas into distributed but integrated multimodal representations. Transmodal areas in the midtemporal cortex, Wernicke's area, the hippocampal-entorhinal complex and the posterior parietal cortex provide critical gateways for transforming perception into recognition, word-forms into meaning, scenes and events into experiences, and spatial locations into targets for exploration. All cognitive processes arise from analogous associative transformations of similar sets of sensory inputs. The differences in the resultant cognitive operation are determined by the anatomical and physiological properties of the transmodal node that acts as the critical gateway for the dominant transformation. Interconnected sets of transmodal nodes provide anatomical and computational epicentres for large-scale neurocognitive networks. In keeping with the principles of selectively distributed processing, each epicentre of a large-scale network displays a relative specialization for a specific behavioural component of its principal neurospychological domain. The destruction of transmodal epicentres causes global impairments such as multimodal anomia, neglect and amnesia, whereas their selective disconnection from relevant unimodal areas elicits modality-specific impairments such as prosopagnosia, pure word blindness and category-specific anomias. The human brain contains at least five anatomically distinct networks. The network for spatial awareness is based on transmodal epicentres in the posterior parietal cortex and the frontal eye fields; the language network on epicentres in Wernicke's and Broca's areas; the explicit memory/emotion network on epicentres in the hippocampal-entorhinal complex and the amygdala; the face-object recognition network on epicentres in the midtemporal and temporopolar cortices; and the working memory-executive function network on epicentres in the lateral prefrontal cortex and perhaps the posterior parietal cortex. Individual sensory modalities give rise to streams of processing directed to transmodal nodes belonging to each of these networks. The fidelity of sensory channels is actively protected through approximately four synaptic levels of sensory-fugal processing. The modality-specific cortices at these four synaptic levels encode the most veridical representations of experience. Attentional, motivational and emotional modulations, including those related to working memory, novelty-seeking and mental imagery, become increasingly more pronounced within downstream components of unimodal areas, where they help to create a highly edited subjective version of the world. (ABSTRACT TRUNCATED)

Ecological Sources of Selection on Avian Sounds

Abstract: This study describes selection derived from habitat acoustics on the physical structure of avian sounds. Sound propagation tests were made in forest, edge, and grassland habitats in Panama to quantify pure tone and random noise band sound transmission levels. The sounds of bird species in each habitat were analyzed to determine the emphasized frequency, frequency range, and sound type (whether pure tonelike or highly modulated). Forest habitats differ from grass and edge in that a narrow range of frequencies (1,585-2,500 Hz) has lower sound attenuation than lower or higher frequencies. Attenuation increases rapidly above 2,500 Hz. Bird sounds from species occurring at the lower forest levels were found to be predominantly pure tonelike with a frequency emphasized averaging 2,200 Hz, conforming to the predictions based on sound propagation tests. The edge habitat is characterized by a wide range of frequencies having a generally similar attenuation rate. Pure tone and random noise band sounds did not diffe...

Active noise control: a tutorial review

Abstract: Active noise control (ANC) is achieved by introducing a cancelling "antinoise" wave through an appropriate array of secondary sources. These secondary sources are interconnected through an electronic system using a specific signal processing algorithm for the particular cancellation scheme. ANC has application to a wide variety of problems in manufacturing, industrial operations, and consumer products. The emphasis of this paper is on the practical aspects of ANC systems in terms of adaptive signal processing and digital signal processing (DSP) implementation for real-world applications. In this paper, the basic adaptive algorithm for ANC is developed and analyzed based on single-channel broad-band feedforward control. This algorithm is then modified for narrow-band feedforward and adaptive feedback control. In turn, these single-channel ANC algorithms are expanded to multiple-channel cases. Various online secondary-path modeling techniques and special adaptive algorithms, such as lattice, frequency-domain, subband, and recursive-least-squares, are also introduced. Applications of these techniques to actual problems are highlighted by several examples.

Physical constraints on acoustic communication in the atmosphere: Implications for the evolution of animal vocalizations

Abstract: 1. Acoustic communication requires not only detection of the signal but also discrimination of differences among signals by the receiver. Attenuation and degradation of acoustic signals during transmission through the atmosphere will impose limits on acoustic communication. Attenuation of sound during atmospheric transmission results primarily from atmospheric absorption, ground attenuation, scattering of a sound beam, and deflection of sound by stratified media. For maximum range of detection, therefore, animals should favor optimal positions in their habitat and optimal weather conditions. Frequency-dependent attenuation seems not to differ consistently among major classes of terrestrial habitats, such as forests and fields. Increased scattering of higher frequencies from vegetation in forests is in part matched by scattering from micrometerological heterogeneities in the open. 2. In addition to frequency-dependent attenuation, two kinds of degradation during atmospheric transmission will limit a receiver's ability to resolve differences among acoustic signals: the accumulation of irregular amplitude fluctuations from nonstationary heterogeneities, often atmospheric turbulence, and reverberation. Both types of degradation affect temporal patterns of amplitude or intensity modulation more than patterns of frequency modulation. Both effects should increase with carrier frequency, as they depend on the relationship between wavelength and the dimensions of scattering heterogeneities. Irregular amplitude fluctuations are more severe in open habitats and primarily mask low frequencies of amplitude modulation; reverberations are more severe in forested habitats and primarily mask high frequencies of amplitude modulation and rapid, repetitive frequency modulation. This difference between forested and open habitats could explain previous reports that birds in the undergrowth of tropical forests avoid rapid frequency modulation in their long-range vocalizations. 3. Maximum range of detection is probably not the primary selection pressure on many animal vocalizations, even for territorial advertisement, except perhaps in tropical forests. Instead, acoustic signals might incorporate features that degrade predictably with range to permit a receiver to estimate the signaler's distance. Future investigations might explore the propagation of animal vocalizations in relation to the usual spacing of animals in their habitat. Features that encode different kinds of information, such as individual and species identity, might propagate to different distances. 4. Measurements of the transmission of sound in natural environments have often not controlled several important parameters. First, the effects of gound attenuation and scattering are not linear with range; consequently measurements of excess attenuation over different ranges in the same environment might differ. Second, the directionality of speakers and microphones will affect measurements of attenuation and reverberations in scattering environments. Third, as stationary waves shift with frequency, any single microphone placement will lie in a null for some frequencies and in a maximum for others.