Bill G. Watters

Speech Privacy in Buildings

Obtaining adequate speech privacy in modern buildings is one of the important goals of the architect and consultant. This paper deals with the development of a rating method which takes into account the several factors influencing speech privacy. Our work in this area began with a brief laboratory study. The results indicated that speech privacy is related to speech intelligibility rather than to level. The initial experiments were supplemented with an analysis of about 40 case histories representing about 400 pairs of spaces in different kinds of buildings. There appears to be good correlation between the articulation index of intruding speech sound and the reactions of building occupants.

Acoustics of Philharmonic Hall, New York, during Its First Season

Acousticians, musicians, and the community at large have taken a lively interest in Philharmonic Hall, the first building to be completed at Lincoln Center for the Performing Arts in New York, N.Y. This interest derives in part from the fact that Philharmonic Hall is the first major hall in nearly 30 years to be built principally for concert uses in this country, but also because the acoustics of the Hall have excited a wide range of opinion since the opening, despite considerable effort to assure fine sound on the part of all who participated in the design. This paper presents the original design goals for Philharmonic Hall and, with reference to the goals, evaluates the Halls history, during the first year of use.

Acoustical Behavior of Some Engine Test Cell Structures

This paper presents some recent data on the acoustical behavior of certain components of engine test cell structures. These data include information on (a) the directivity patterns of vertical stacks and (b) the noise reduction provided by some water‐spray systems, (c) the Soundstream absorber, and (d) a 90° vertical bend.

Detection of buried landmines by imaging with surface waves

A technique has been developed to search an area of soil for buried landmines from a remote position. A two‐dimensional synthetic aperture array of seismic sources and receivers is laid down adjacent to the search area. Broadband seismic sources generate Rayleigh surface waves that illuminate a search area out to a radius of 6 m and a depth of about 0.5 m. An array of vertical geophones receives backscattered signals that are recorded digitally. Unconsolidated soils have high rates of attenuation so an array with up to 21‐dB of gain is used. A delay‐and‐sum near‐field beamformer computes a 60×80 pixel image of the region’s scattering strength. The search area image displays the location and character of landmine echoes along with clutter. A large amount of field data has been collected at several sights. The mine echoes have been detected at ranges up to 5 m (Pd=0.8). Landmines have been distinguished from rocks and holes, and false alarms due to system artifacts are being reduced. [Work supported by U.S....

Acoustics of Multipurpose Performance Facilities: An Evaluation of the Objective and Subjective Acoustical Characteristics of Several Recently Completed Halls

Multipurpose halls in the size range of 2000–2500 seats are discussed in terms of program uses as well as architectural and acoustical design considerations. Specific examples from several recently completed projects illustrate approaches to and results of acoustical variability either of sound‐absorption or “sending‐end” reflectivity or both. Particular emphasis is placed on the objective and subjective evaluation of the natural and electroacoustics characteristics of the completed facilities in relation to initial design criteria.

Acoustics of Open Plan Spaces—Some Case Histories

Open planning in office buildings and in schools has presented a new range of problems in the control of the acoustical environment. Several case histories are described, including objective measurements and subjective reactions of the occupants. A preliminary scheme for the systematic analysis and evaluation of privacy and communication problems in these types of spaces is presented. The analysis technique utilizes the widely known AI concept in developing an objective rating for privacy (or communication) and corresponds reasonably well with observed subjective reactions in field situations.

Rôle of Model Testing in the Acoustical Design of Auditoria

The flow of sound from the stage of an auditorium to the audience is controlled both by the gross auditorium shape and by the architectural treatment of the interior surfaces. Both of these are, of course, primary architectural as well as acoustical elements. We have found acoustical testing of a scale model to be a valuable aid in achieving an architecturally acceptable design that yields “sound patterns” that have the desired frequency and amplitude characteristics and the appropriate times of arrival. Test data and instrumentation techniques are described; typical auditorium‐design problems are illustrated.

Noise generation by rain on lightweight roofs

Raindrops impacting on the lightweight roofs of buildings, such as performing arts facilities and sports arenas, may generate noise of sufficient intensity to interfere with hearing conditions. This paper identifies the key physical parameters that control the noise generation process and presents an analytical model that permits the prediction of the intensity and spectral distribution of rain‐induced noise.

Sound Isolation Criteria for Music Activities

Laboratory demonstrations and tests have been conducted by the authors to establish maximum allowable intrusive music levels for music teaching spaces. Calibrated tape recordings of a music education class, band, orchestra, and choir practice were reproduced through a spectrum shaping filter network and a high‐quality sound reproduction system. Subjective responses of test subjects were recorded for various levels of intrusive noise in a controlled acoustical environment. Variations in the background noise levels during the tests confirm the importance of the signal‐to‐noise ratio in music privacy. The test procedures are described, sound‐isolating constructions are evaluated, and tentative sound‐isolation criteria are presented.

Rating Scales for Auditorium Acoustics

Communication of scientific ideas is aided if the essential “dimensions” of the topic being discussed are first identified, and then quantified or scaled. This is as true for subjective as for objective dimensions. We report our most recent efforts to scale the more important subjective dimensions of the effect of the acoustic character of auditoria upon speech and music. Approximately a dozen dimensions have been found useful in communicating subjective evaluations of various halls. Examples are: brassiness, brilliance, and over‐all loudness resulting in a hall for a standard speech or music source.