Parker W. Hirtle

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.

Partition system for open plan office spaces

The partition system disclosed herein incorporates apparatus for generating a speech masking acoustic field. Respective speakers are mounted near the bottom of each of a plurality of partition panel segments defining each work space and are aimed horizontally. These speakers are driven by respective signals which are subjectively incoherent as to frequencies of interest in the masking spectrum, thereby to provide a sound field without perceptible discontinuities.

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.

Speech privacy in buildings: A review

Studies on speech privacy problems in buildings at Bolt Beranek and Newman begun in the mid 1950s showed convincingly that a person’s sense of acoustical privacy was directly related to the intelligibility of the intruding speech over the continuous ambient sound present [Cavanaugh et. al., J. Acoust. Soc. Am. 34, 475–492 (1962)]. Both in laboratory and in real‐world settings people feel they have confidential privacy when the articulation index (AI) of the intruding speech is 0.05 or less. Higher values of AI are acceptable for less demanding tasks, i.e., normal privacy. The method quantifies each of the significant variables involved and compares a summary of these metrics with response data for prior case histories both to predict, and, in the case of existing situations, to evaluate speech privacy conditions. R. W. Young reviewed the analysis method and showed that sufficient accuracy was preserved if simple, commonly used A‐scale sound levels were used in place of more cumbersome frequency‐based metr...

Acoustical design considerations for two air‐supported structures

This paper presents information on the acoustical design of the Hubert H. Humphrey Metrodome in Minneapolis, Minnesota and the Dalhousie University Athletics Complex (Dalplex) in Halifax, Nova Scotia. The Hubert H. Humphrey Metrodome seats up to 63 000 people under an air‐supported fabric roof. Major concerns that are discussed were reverberation control and the design of a system of loudspeaker clusters that are suspended from the roof membrane and maintain proper orientation when the structure is moved by changes in wind loading. The main feature of Dalplex, which is located in a residential neighborhood, is a 300 ft by 240 ft stainless steel air‐supported roof over the field house and running track. This 116‐in.‐thick stainless steel membrane presented some unique acoustical problems that had to be addressed, including control of reverberation in the fieldhouse, reduction of the noise of rain on the metal roof to acceptable levels, and reduction of crowd noise transmitted through the roof to nearby hou...

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.

Noise Control in Home Heating and Air‐Conditioning Systems

The procedures for estimation of the noise generated by home heating and air‐conditioning systems will be discussed. The discussion on heating systems will include forced hot‐air and water systems. To be included in the air‐conditioning systems discussion are window units and central air‐conditioning systems. The primary noise generators for heating systems include the furnace, burner, blowers, and unit heaters. The primary sources of noise in air‐conditioning systems are the compressor, condenser (evaporative, cooling tower, or air‐cooled), and blowers. Other sources of noise within such systems include the piping, circulators, ductwork, registers, and diffusers. Noise‐control techniques will include location of the equipment, dissipative silencers, enclosures, lining of the ductwork, sizing of the ductwork, and vibration isolation. In addition, problems associated with the location of diffusers and registers, such as crosstalk between rooms, will be presented as well as methods for eliminating these pro...

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.

The Reliability of Field Measurements of Sound Isolating Partitions

Transmission loss measurements have been made on field installations of several partitions. Results of field measurements of the same components in several different installations are compared. Some comparisons are made with laboratory measurements of installations which attempt to duplicate field conditions and those which do not.

Comparison between Predicted and Observed Satisfaction for Speech Privacy in Buildings

The notion of a single number rating for speech privacy problems in buildings [B. G. Watters, J. Acoust. Soc. Am. 32, 917 (1960)] has been developed further. The resulting system rates both the measured noise reduction of the isolating construction and the background (masking) noise levels. It also takes into account those other factors that determine the acceptability of speech privacy between spaces such as the size of the rooms, the level of speech effort in the spaces, and the degree of privacy needed by the occupants. The ratings calculated, using this system, are compared with observed subjective evaluations of the occupants in a large number of field situations.