Stephen J. Lind

Field study of the annoyance of low-frequency runway sideline noise

Noise from aircraft ground operations often reaches residences in the vicinity of airports via grazing incidence paths that attenuate high-frequency noise more than air-to-ground propagation paths, thus increasing the relative low-frequency content of such noise with respect to overflight noise. Outdoor A-weighted noise measurements may not appropriately reflect low-frequency noise levels that can induce potentially annoying secondary emissions inside residences near runways. Contours of low-frequency noise levels were estimated in a residential area adjacent to a busy runway from multi-site measurements of composite maximum spectra of runway sideline noise in the one-third octave bands between 25 and 80 Hz, inclusive. Neighborhood residents were interviewed to determine the prevalence of annoyance attributable to runway sideline noise at frequencies below 100 Hz, and of its audible manifestations inside homes. Survey respondents highly annoyed by rattle and vibration were concentrated in areas with low-f...

Sound rating of a new air handling product

It is important in building design to have an accurate acoustical description of equipment that will operate in the building. Noise from air conditioning systems is often a significant contributor to the building acoustic environment. In order to design the building correctly, the sound levels produced by the equipment must be known. Current theoretical or computer modeling methods are not able to accurately predict the resulting unit sound levels. The sound levels produced depend on many factors including equipment design, operating conditions, options chosen, and sound component. Empirical models are needed. The test method to develop the models follows Air Conditioning, Heating, and Refrigeration Institute Standard 260. Sound power levels for a range of fan sizes, types, and operating conditions are measured for the discharge, inlet, and casing sound components. Equipment options that affect the sound as it propagates through the equipment are also measured. The test results are used to create mathemat...

An equipment manufacturer's perspective of acoustical standards

As an HVAC manufacturer, it is our goal to create safe, comfortable, and efficient environments (i.e., classrooms, health care facilities, offices, etc.). Standards are useful in gaining agreement regarding the appropriate sound levels for these spaces and establishing how to verify that these levels are met. Regular interaction and participation in writing the standards helps to ensure that all are aware of the requirements and it also allows participants to provide input on what is practical. Participating in the process also helps to prevent adversarial relations between the parties involved in the design and use of the equipment. Standards also provide the technical basis for which manufacturers and customers can make a valid comparison of different products. The information provided is useful in the design process. Sound power of the equipment is a commonly used metric. Standardizing sound power measurement methods reduces the customers risk by making sure the published sound levels are representati...

Sound quality descriptors for HVAC equipment from ARI Standards

The Air Conditioning and Refrigeration Institute (ARI) has several standards that provide methods to evaluate the sound quality of heating ventilating and air‐conditioning (HVAC) equipment. These include Standard 270 Sound rating of outdoor unitary equipment, Standard 350 Sound rating of non‐ducted indoor air‐conditioning equipment, and Standard 1140P Procedures for evaluating sound quality of HVAC equipment. The preferred method in these standards is best described in Standard 1140P, which uses one‐third octave band sound power levels that are weighted to adjust for the sensitivity to frequency distribution and presence of tones, and are then converted to a single number sound quality indicator. The tone adjustment is based on the projection of a given one‐third octave band level relative to the average of the adjacent one‐third octave bands. An alternate use of Zwicker method B to determine loudness and loudness level is also provided in ARI Standard 1140P. These standards provide a convenient method by which complex sounds for similar products may be compared.

Determination of reference sound source sound power levels using ARI Standard 250

The Air Conditioning and Refrigeration Institute (ARI) Standard 250 Performance and Calibration of Reference Sound Sources was used to establish one‐third octave band sound power levels of several reference sound sources (RSS). The work was carried out in an anechoic chamber that was qualified at frequencies of 100 Hz and above using ANSI S12.35. Measurements were made with circular slices around the RSS at heights from 5 cm to 195 cm in 10 cm increments using both intensity and sound pressure. A 19 point fixed array was also employed for comparison of one of the sources. Sound power levels were compared from the 50 Hz to the 10 000 Hz one‐third octave bands using several methods. The results are compared to the sound power levels provided by the manufacturer.

Air handler sound power prediction method based on ARI Standard 260

A method of predicting air handler sound power based on ratings for a product line is described. The method provides octave band sound power levels based on ratings obtained using Air‐Conditioning and Refrigeration Institute (ARI) Standard 260 Sound Rating Of Ducted Air Moving And Conditioning Equipment. Detailed sound power information for HVAC equipment is not always available, but it is important in accurately predicting noise levels in acoustically sensitive spaces. To address this need, a rating program was undertaken using ARI 260. This standard is a reverberant room technique for sound rating ducted air conditioning equipment using a reference sound source substitution method. Since sound travels from the source to receiver along numerous paths, this standard differentiates between sound power emanating from several common paths called components. Components for this project included ducted discharge, free inlet plus casing, ducted inlet and casing. The standard provides guidance on adequate number...

On the utility of extending the low‐frequency range of standards for sound isolation in buildings

Frequencies above 100 Hz are commonly considered in sound insulation computations as specified by ASTM E413 and ISO 717. This is appropriate for concerns about speech privacy in interior spaces. However, aircraft ground operations (including takeoff roll, engine run‐ups, and thrust reverser deployment) may expose buildings near runways to appreciable amounts of energy at yet lower frequencies. Several studies of low‐frequency aircraft noise levels have recently been completed in the United States, and the U.S. Federal Aviation Administration is paying for architectural treatments to reduce low‐frequency aircraft noise in residences near one airport. This paper describes the findings of a recent social survey of residential annoyance caused by low‐frequency runway sideline noise, including noise in the 25 to 80 Hz one‐third octave bands, and reviews other evidence about the role of low‐frequency energy in sound isolation metrics.

Social survey of the annoyance of low‐frequency aircraft ground noise

Concerns about the appropriateness of representing low‐frequency aircraft ground and near‐ground noise in A‐weighted units, and about the adequacy of standard interpretive criteria for assessing community response to low‐frequency noises, are becoming more common at large civil airports. Residents of a neighborhood adjacent to a busy runway were interviewed to determine the annoyance of runway sideline noise at frequencies below 100 Hz, and of its audible manifestations inside homes. Extensive measurements were made to estimate low‐frequency noise contours in the interviewing area, and street addresses of respondents were geo‐coded to permit assignment of low‐frequency noise levels to each household. Residents who were highly annoyed by low‐frequency sideline noise were concentrated in areas with maximum sound levels summed in one‐third octave bands between 25 and 80 Hz (inclusive) that were in excess of 75–80 dB. These levels are consistent with Hubbard’s (1980) estimates of low‐frequency airborne sound ...

Influence of low‐frequency content on rate of growth of annoyance of high‐energy impulsive sounds

Various ‘‘corrections’’ have been suggested to measures of high‐energy impulsive sounds to account for their seemingly anomalous annoyance, some on the basis of the findings of studies that may not have accurately reproduced the low‐frequency content of high‐energy impulses. The present study measured rates of growth of annoyance of impulsive and nonimpulsive sounds by adaptive paired comparisons of the annoyance of five variable level signals and 29 impulsive and nonimpulsive fixed level signals. All test sounds were presented for judgment in a specially designed low‐frequency test facility. When the annoyance of an aircraft flyover was compared to that of a low‐frequency band of noise and of sonic booms accompanied by rattle, the relative rates of growth of annoyance were not much different from 1:1. When the annoyance of sonic booms that were not accompanied by rattle was compared with that of sounds containing more higher‐frequency energy (an aircraft flyover and an octave band of noise centered at 1 ...

Investigation of low frequency aircraft noise near airports

Noise levels due to aircraft departures were measured at four locations near Minneapolis–Saint Paul International Airport and at seven locations near Los Angeles International Airport. A‐weighted overall levels and one‐third octave band levels between 25 and 80 Hz were obtained. Levels for 46 aircraft were analyzed for Minneapolis and 122 for Los Angeles. A linear regression was performed on the low‐frequency levels versus the A‐weighted levels for the locations to the sidelines of the active runways. The relationship between low‐frequency noise and A‐weighted sound pressure level for different distances was applied to A‐weighted levels obtained from INM to estimate the low‐frequency noise levels from a proposed runway. Estimates were made regarding which parts of the community would experience perceptible vibrations.