<?xml version="1.0" encoding="utf-8"?><rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom"><channel><title>TRB Publications Index</title><link>http://pubsindex.trb.org/</link><atom:link href="http://pubsindex.trb.org/common/TRIS Suite/feeds/rss.aspx?tc=NN%3AGumpq" rel="self" type="application/rss+xml" /><description></description><language>en-us</language><copyright>Copyright © 2015. National Academy of Sciences. All rights reserved.</copyright><docs>http://blogs.law.harvard.edu/tech/rss</docs><managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor><webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster><image><title>TRB Publications Index</title><url>http://pubsindex.trb.org/Images/PageHeader-wTitle.png</url><link>http://pubsindex.trb.org/</link></image><item><title>Instrumentation to Measure On-Road Cyclist Noise Exposure: Considerations for Study Design with Smartphones and Sound Level Meters</title><link>http://pubsindex.trb.org/view/2137654</link><description><![CDATA[Cyclist noise exposure has implications for health, comfort, and safety. Methods used for in situ measurement of on-road noise levels for cyclists vary, and the effects of key study design factors have not been investigated. To enable reliable research into cyclist noise exposure, this study aims to determine the accuracy of smartphone noise measurements in comparison with a sound level meter (SLM) reference instrument, and how noise levels are affected by travel speed, air speed, sensor placement, and use of a windscreen. Field data were collected with paired instruments in a typical urban cycling scenario, and comparisons made varying one design factor at a time (smartphone versus SLM, with versus without windscreen, handlebar versus shoulder placement, etc.). Results show that smartphones can generate reliable measurements (compared with SLM) of high-resolution (1-s) cyclist exposure for C-weighted noise, but not A-weighted noise. Sensor placement and windscreen have small effects on noise readings, but air speed and travel speed greatly affect measured noise levels. Future studies measuring on-road noise must consider the effects of wind- and bicycle-generated noise to ensure internal validity. Studies should also consider both study objectives and instrumentation when selecting a noise measure (frequency weighting). Research is needed into bicycle noise generation and perception of traffic noise by cyclists to enhance the reliability of future studies.]]></description><pubDate>Thu, 16 Mar 2023 09:50:21 GMT</pubDate><guid>http://pubsindex.trb.org/view/2137654</guid></item><item><title>Field Evaluation of Reflected Noise from a Single Noise Barrier</title><link>http://pubsindex.trb.org/view/1566104</link><description><![CDATA[State departments of transportation periodically receive complaints from residents about increases in traffic noise that residents believe are the result of noise reflected from a new noise barrier added across the roadway from them.  The research documented in this report analyzes the characteristics of sound reflected from a noise barrier to the opposite side of a highway. The research effort included collecting field data at eight monitoring sites, five with sound-reflective barriers and three with sound-absorptive barriers. Spectrograms, difference spectrograms, psychoacoustic metrics, and changes in sound levels were used to analyze differences in sound levels and frequency patterns associated with the two types of noise barriers.  The results of this study provide insights into the nature of reflected noise and can be used to support the appropriate use of sound-absorptive surfaces on barriers.]]></description><pubDate>Wed, 31 Oct 2018 11:36:28 GMT</pubDate><guid>http://pubsindex.trb.org/view/1566104</guid></item><item><title>Appendices to NCHRP Research Report 842</title><link>http://pubsindex.trb.org/view/1479188</link><description><![CDATA[This document contains nine appendices to NCHRP Research Report 842: Mapping Heavy Vehicle Noise Source Heights for Highway Noise Analysis. NCHRP Research Report 842 provides an analysis to determine height distributions and spectral content for heavy vehicle noise sources. The report also explores establishing and beginning the development of an extended heavy vehicle (truck and bus) noise source database for incorporation into traffic noise models, including future versions of the U.S. Federal Highway Administration (FHWA) Transportation Noise Model (TNM) acoustical code. The appendices include:  a description of measurement sites; on-board sound intensity results; statistical isolated pass-by discussion; additional contour analysis for heavy trucks; methods of frequency weighting; two-point source distribution development; barrier/distribution analysis; medium trucks discussion; and a light vehicles and buses summary.]]></description><pubDate>Thu, 03 Aug 2017 13:38:44 GMT</pubDate><guid>http://pubsindex.trb.org/view/1479188</guid></item><item><title>Evaluating Methods for Determining Interior Noise Levels Used in Airport Sound Insulation Programs</title><link>http://pubsindex.trb.org/view/1403017</link><description><![CDATA[This report provides guidance for selecting and implementing methods for measuring noise level reduction in dwellings associated with airport noise insulation programs.  The research complements the results of ACRP Report 89: Guidelines for Airport Sound Insulation Programs and was undertaken to assess the accuracy and validity of various noise level reduction measurement procedures currently used in airport noise insulation programs. Acoustical field measurements were made at 10 homes near San Diego International Airport and nine homes near Boston Logan International Airport. Seven measurement methods were tested: outdoor ground-level artificial sound source (loudspeaker); outdoor elevated artificial source (loudspeaker); indoor artificial sound source (loudspeaker); aircraft flyover: fixed microphone; aircraft flyover: moving microphone; architectural survey and noise reduction calculations; and acoustic intensity measurements, exterior loudspeaker and interior intensity.  The report includes a summary of sound insulation theory and the science behind noise level reduction, and an overview of FAA-sponsored noise insulation programs. The report also provides guidance, including a decision matrix, for selecting an appropriate acoustical testing method. Lastly, the report provides suggested practices for each measurement technique, based on the results of the research.]]></description><pubDate>Mon, 04 Apr 2016 13:09:06 GMT</pubDate><guid>http://pubsindex.trb.org/view/1403017</guid></item><item><title>Development of Tire-Pavement Noise Evaluation Methodology in India</title><link>http://pubsindex.trb.org/view/1289104</link><description><![CDATA[Globally, roadway traffic noise is a growing problem, particularly, in the urban areas and is considered a sustainable “quality of life” issue. In the context of India as well, transportation-related noise is a major concern in the urban areas of major cities, particularly, in the vicinity of hospitals, schools, libraries, etc. The major objective of this research study was to develop a methodology to evaluate tire / pavement noise of the various road types and sections in Bangalore. The scope of the effort included field noise measurements of the seventeen conventional asphalt concrete (AC), four portland cement concrete (PCC), and two Plastic Modified asphalt concrete (PMAC) in Bangalore city covering about 24 kilometers of roadway stretches at varying traffic speeds. Field noise measurements were performed using a noise meter mounted underneath a trailer developed in this study and attached to the parent vehicle (car). Overall, PMAC sections produced the highest noise levels than the PCC followed by the conventional AC sections; PMAC mix type had an average difference of about 6-8 dB compared with the AC mix, and 1-2 dB in comparison with the PCC mix types. It is noteworthy that although many traffic noise studies have been conducted in India, the contribution of tire / pavement interface noise to the overall noise has not been developed and/or established till date. The approach taken in this study is first of its kind within the framework of tire / road noise research and development in India.]]></description><pubDate>Mon, 24 Feb 2014 08:42:48 GMT</pubDate><guid>http://pubsindex.trb.org/view/1289104</guid></item><item><title>Using Onboard Sound Intensity Measurements to Interpret Results of Traffic Noise Modeling</title><link>http://pubsindex.trb.org/view/1241813</link><description><![CDATA[With the evaluation of noise impacts and noise abatement under the requirements of 23 CFR 772, Procedures for Abatement of Highway Traffic Noise, traffic noise levels are calculated with FHWA’s Traffic Noise Model (TNM). The TNM calculates traffic noise levels on the basis of the geometry of the site and traffic volumes, mix, and speeds. The TNM does not currently account for pavement type or condition, atypical vehicle noise populations, transparent shielding, reflections, or meteorological conditions. For these reasons, noise measurements are conducted, and traffic noise model adjustments and calibration factors are developed. For several highway studies recently conducted in California, onboard sound intensity (OBSI) measurements were made concurrent to the traditional wayside noise measurements along the length of the freeway to be studied, to account for the existing pavement type and condition of the freeway. Use of OBSI data, when compared with the calculated TNM average pavement OBSI level, has helped to interpret calibration factors that had been developed in the TNM on the basis of standard modeling practices. A description is given of how the OBSI can be used as a supplementary tool to help interpret calibration factors developed for a TNM model.]]></description><pubDate>Wed, 27 Feb 2013 16:36:12 GMT</pubDate><guid>http://pubsindex.trb.org/view/1241813</guid></item><item><title>Active Control of Noise Transmission into Payload Fairings Using Distributed Active Vibration Absorbers and Loudspeakers</title><link>http://pubsindex.trb.org/view/813728</link><description><![CDATA[This paper presents an experimental study on the active control of sound transmission in a large cylinder with a similar construction to that of a composite payload fairing. A feed forward control system utilized both structural and acoustic actuators with the objective of comparing their performance. The paper determined that the four loudspeakers system and the four DAVA systems produced similar reductions but that it was the acausality in the optimal controller filters that restricted performance. Because of this, the control system could only control the resonance peaks in the system (i.e. the most predictable parts of the spectrum). The optimal performance was calculated using measured transfer functions and showed that 13.6dB was achievable if causality was not a problem and this was re-enforce by experiments using added delay (9.1dB measured across the band). From this it can be concluded that 8 control channels provided sufficient control complexity in order to achieve high levels of broadband control but that the spatial distribution and coupling of the actuators limits performance. It was also shown that 134.7dB of external noise levels could be controlled using loudspeakers weighing 9kg. This is very similar to but slightly larger than the weight of the structural actuators (DAVAs) required for control of the same level of exterior noise.]]></description><pubDate>Fri, 27 Jul 2007 07:06:37 GMT</pubDate><guid>http://pubsindex.trb.org/view/813728</guid></item><item><title>Aspects of HDD Tone Measurements: Sound Power Microphones as Bystander Positions and Autocorrelation Analysis</title><link>http://pubsindex.trb.org/view/813717</link><description><![CDATA[This paper describes how tone content has long been known to be important in hard disk drive (HDD) sound quality. The tone-to-noise ratio (TNR) has been in use for many years, while the prominence ratio (PR) is more recent. While a system-level test using a binaural head at the system operator position is the most reflective of the end-user experience, HDD-level testing is still conducted for development and specification purposes. The HDD itself has no operator position, and even the bystander positions are nebulous since the HDD can be mounted in any orientation inside a system. The current wording in ECMA-74 (§8.6.2) specifies four bystander positions 1.5 m above the floor. These microphone positions are separate from the microphones that are used to measure sound power in a hemi-anechoic chamber, typically 10 microphones in a fixed hemisphere or a lesser number on a rotating boom. Given the rather arbitrary nature of the bystander positions, this paper investigates the use of the existing sound power microphones as bystander positions to increase measurement efficiency and spatial sampling. Whatever microphone positions are used as the bystander positions, the spectra gathered will be evaluated using the TNR and/or PR methods. The PR method is more amenable to automated tone analysis compared to the TNR method since PR does not require exact identification of peak center frequency or determination of peak width. This is because PR is based on summing the total mean square value in the lower, middle, and upper critical bands, thus reducing the effect of fine detail in the spectrum. Unless the spectrum is highly structured, a small shift in center frequency will generally have a small effect on the PR value. If the only concern is whether any peak exceeds the prominence threshold, such small changes are negligible; if a peak is near the prominence threshold a detailed analysis centered exactly on the peak in question can always be conducted for a more precise answer. Consequently, PR is sometimes simply calculated at intervals with no attempt at peak identification. Unfortunately, if the spectrum contains a peak which is approximately one critical band wide and the PR is evaluated near the center of this peak, it can be identified as highly prominent even though the peak does not represent a prominent discrete tone. This paper will show an analysis using autocorrelation of a spectrogram to determine the time-domain behavior of such a candidate peak and verify the applicability of PR for that peak.]]></description><pubDate>Fri, 27 Jul 2007 07:06:37 GMT</pubDate><guid>http://pubsindex.trb.org/view/813717</guid></item><item><title>Proposed Criteria for Low Frequency Noise from Combustion Turbine Power Plants</title><link>http://pubsindex.trb.org/view/813731</link><description><![CDATA[This paper proposes updated “C” weighted overall level limits that are necessary to avoid, or at least minimize, resident complaints from low-frequency industrial sources. The limits proposed are developed mainly from extensive experience at many problem installations using open-cycle combustion turbines for peak power generation.  In open cycle operation, combustion turbine exhaust gases are discharged to atmosphere through a silencer/stack system. Low frequency noise problems are only associated with exhaust stack emissions from open cycle turbine plants. Such plants are used to drive generators for peak load applications by power companies, and to drive compressors for gas and liquid pipelines. Peak electrical loads usually occur during very hot summer months and/or very cold winter months. Typically the units operate daily during these periods, starting in early afternoon and shutting down by midnight. The units operate 24/7 for pipeline applications. As early as 1971, ANSI B133.8, “Gas Turbine Installation Sound Emissions” recommends a limit of 75 to 80 dBC to minimize the problem of low frequency noise or infrasound problems that were surfacing at that time. Experience since 1971 has shown that this recommendation is woefully inadequat, and that the problem continues to reoccur for combustion turbine open cycle plants. The paper shows that turbine exhaust spectra are tonal in nature as are most sources of low frequency noise. Therefore, it is believed that the proposed limits are also valid for other steady sources of low frequency noise, such as, compressor stations, wind turbines, diesel generators and others. The paper also shows that the standardized “C” weighted overall level is an adequate and ideal metric for regulation purposes.]]></description><pubDate>Fri, 27 Jul 2007 07:06:36 GMT</pubDate><guid>http://pubsindex.trb.org/view/813731</guid></item><item><title>Multiple Analysis and Measurement Methods to Confirm the Absence of Noise Impacts from a Power Plant</title><link>http://pubsindex.trb.org/view/813732</link><description><![CDATA[This paper describes how the licensing of a power plant project presents the analysts with a series of challenges. This project involved the replacement of two power units (Units 1 and 2) with three combined-cycle units (Units 5, 6 and 7) at an existing power plant. The plant is adjacent to the coastline, which proved to be the dominant noise source at the nearest noise-sensitive receptors. In addition to the noise from surf, other major ambient noise sources included road traffic and a nearby international airport. The general layout of the site and surroundings and the major project features are shown and the initial analysis, which was straightforward in nature, concluded that noise levels with the project would be within the relevant regulations and standards. The project would replace old, inefficient equipment with new, more powerful, efficient and quieter equipment (as abated). Additionally, the new equipment was sited far enough from the residences (approximately 670 meters) and would be acoustically shielded by the remaining, still operational units (Units 3 and 4). Subsequently however, several of the nearest residents (located south of the plant) raised a question: Could the removal, as part of the project, of two large fuel oil tanks from the southern end of the plant property cause an increase in the noise levels received at their homes from the remaining Units 3 and 4? The fuel oil tanks (each of which is 67 meters in diameter and 15 meters in height) block much or all of the direct view to the power units from several of the nearest residences. By removing the tanks, residents would have a less obstructed view of the power units, although intervening terrain and structures would still shield varying portions of the facility, depending upon the observation point. Based upon initial noise measurements, analysis and critical listening conducted during the site visits, the analysts did not believe that removal of the fuel oil tanks would in fact result in higher noise levels, because of the large distances between the plant and the residences, but more importantly, by relatively high ambient levels. The difficulty, however, was in substantiating this quantitatively - in effect, trying to do the impossible and “prove a negative”.]]></description><pubDate>Fri, 27 Jul 2007 07:06:36 GMT</pubDate><guid>http://pubsindex.trb.org/view/813732</guid></item><item><title>Noise Insulation Performance of Buildings Near Airports: Measurement Issues and Perspectives</title><link>http://pubsindex.trb.org/view/813704</link><description><![CDATA[This paper describes how, for nearly 15 years, the Federal Aviation Administration (FAA) has been sponsoring retrofit noise insulation treatment of residences, schools and places of worship that are experiencing day-night average sound level (DNL) noise exposure at or above 65 dB from airport operations. The FAA program requires performance testing in the form of pre-construction and post-construction acoustical measurements in order to demonstrate compliance with a maximum post-construction interior DNL noise exposure standard of 45 dB and a minimum post-construction A-weighted sound level improvement (NLR) standard of 5 dB. Design of the measurement plan and method is left to the individual acoustical consultant for each airport project; the FAA specifies no measurement standards. Either stationary artificial sound sources or actual aircraft flyovers are used to measure the sound reduction properties of the buildings. The resulting sound reduction data are found to vary considerably within each program as well as among programs. This paper reviews various measurement techniques, evaluates their strengths and weaknesses, and presents recommendations for adjusting data results for signal-to-noise. Measurement data are sensitive to the signal-to-noise ratio in the measurement environment, and an empirical adjustment method is presented for A-weighted measurement results.]]></description><pubDate>Fri, 27 Jul 2007 07:06:36 GMT</pubDate><guid>http://pubsindex.trb.org/view/813704</guid></item><item><title>Characterization of Run-Up and Down Transient Events for a Hard Disk Drive</title><link>http://pubsindex.trb.org/view/813712</link><description><![CDATA[This paper describes how, because of the tireless efforts of engineering teams within the hard disk drive (HDD) industry, the levels of noise emissions from HDD’s has been significantly reduced to the point where customers are requiring transient events be limited in their emissions as well. To date, the standards available for noise emission measurements are limited to steady state events with some mention of impulsive events. However, nothing really addresses time varying events or events that would fall into the “quality of sound” with the exception of ISO532B. But even ISO532B addresses steady state time averaged loudness events using the Zwicker method. Transients that occur, such as latching and de-latching, can be characterized using standardized measurement techniques that are currently in place such as impulsiveness, loudness, and wavelet analysis. Specifically one area of a HDD operation has proven to be hard to characterize, yet has garnered much criticism from customers. That area is the run up and down of the spindle motor as the drive is powered up/shut down or put on standby/awakened from standby. The section of drive consumers that is making this complaint more often is the market where the drives are operated in a very quiet environment (PVR’s, DVR’s, etc). During the spin up cycle some people have described certain events as whiny and hissy in drives that had unacceptable spin ups. Jury tests were conducted to try and find out which time histories were acceptable and which were not. Separate analyses were performed to show what the differences are between the good and the bad. It should be noted that to the HDD industry, characterization during R&amp;D stages is much different than characterization on a mass level during production stages. Sampling at the factory level can reach the 100% mark depending on the customer, market conditions, etc. When the factory turns out X million units per quarter, a quick and efficient method must be found and employed when taking and analyzing data at this level of throughput.]]></description><pubDate>Fri, 27 Jul 2007 07:06:36 GMT</pubDate><guid>http://pubsindex.trb.org/view/813712</guid></item><item><title>A Procedure for Measuring Speech Detection in Directional Noise</title><link>http://pubsindex.trb.org/view/813711</link><description><![CDATA[This paper examined the use of the Bekesy tracking technique for the measuring of directional detection thresholds in noise, in various speech and noise loudspeaker configurations. The tracking technique appears to hold promise as a method for measuring speech thresholds quickly and accurately. Further, the results of this study provide the information necessary to select a subset of loudspeaker configurations that would adequately reflect a listener’s ability to detect speech in directional or nondirectional noise as well as provide the reference data that could be used to establish the normative thresholds. The test should be completed in about 5-6 minutes using suggested configurations.]]></description><pubDate>Fri, 27 Jul 2007 07:06:36 GMT</pubDate><guid>http://pubsindex.trb.org/view/813711</guid></item><item><title>Low-Frequency Noise Effects in Residential Buildings Along a Bus Rapid Transit (BRT) Route</title><link>http://pubsindex.trb.org/view/813733</link><description><![CDATA[This paper summarizes an investigation of low-frequency noise effects that was conducted in residential buildings along the Sliver Line Bus Rapid Transit (BRT) route in Boston, MA. Soon after a new fleet of Neoplan buses began operating on the line, the Massachusetts Bay Transportation Authority (MBTA) received complaints about rumbling noise and vibration from residents who live along the route. The complaints were primarily related to noise and vibration that occurred inside homes when the buses were idling at stops along the line. The Neoplan bus that operates on the Silver Line is an 18.3 m (60 ft) long, articulated, low-floor unit that runs on compressed natural gas (CNG). The bus is powered by a six cylinder, 4-cycle engine that idles at a rotation speed of 700 rpm. In response to the community complaints, an investigation was undertaken to diagnose the problem and develop noise control solutions. Initially, noise and vibration measurements were conducted at affected residences to document the problem, and field tests of a representative bus were performed for diagnostic purposes. Based on the outcome of the initial tests, modifications were made to one of the buses and additional tests were performed. The interim results of this investigation are described below.]]></description><pubDate>Fri, 27 Jul 2007 07:06:36 GMT</pubDate><guid>http://pubsindex.trb.org/view/813733</guid></item><item><title>Handling of Barriers in ISO 9613-2</title><link>http://pubsindex.trb.org/view/813720</link><description><![CDATA[This paper describes how sound barriers, or sound screens as they are called in ISO 9613-2 are one of the primary tools used in noise control engineering. The ability to accurately estimate the attenuation of a sound barrier is critical to the successful noise control design of many industrial facilities. However, far too often noise control engineers ignore the details buried within the barrier attenuation algorithms and rely on computer methods to handle critical calculations. One of the more popular algorithms for barrier insertion loss is that defined by the ISO 9613-2 standard. The ISO 9613-2 screening attenuation equations and rules are cast as a simple method for determining the effectiveness of a sound barrier in the presence of a ground plane. The method is conducive for computer predictions made on personal computers with limited computational resources. It is often used in spreadsheet analysis or in dedicated environmental sound modeling software. Currently, the algorithm is widely used in environmental noise modeling software. Issues associated with the perceived accuracy of the ISO 9613-2 screening algorithm can be broken down into 3 categories: (1) misinterpretations by ISO 9613-2 users of the formulas/rules that can lead to erroneous results or discontinuity of the results; (2) ISO 9613-2’s omissions in regard to rules for handling special cases; and (3) physical phenomena that ISO 9613-2 does not account for. This paper provides a critical assessment of the adequacy of the ISO 9613-2 barrier attenuation algorithm and identifies many misconceptions of its use and deficiencies of the algorithm.]]></description><pubDate>Fri, 27 Jul 2007 07:06:36 GMT</pubDate><guid>http://pubsindex.trb.org/view/813720</guid></item></channel></rss>