Noise Criteria Research Articles

Ambient noise criteria framework for future environmental noise mitigation targets in Singapore

This study aims to establish a framework for outlining future noise mitigation strategies tailored to the unique context of Singapore and evaluates potential precautions. Singapore, as a city-state, is known as a 'city in a garden,' situated in the typically tropical climate. By incorporating a comparative analysis of noise criteria from local guidelines across countries from Europe, America, and Asia, the study aims to place Singapore's acoustic limits within an international context. This comparison, enhanced with the World Health Organization's health and well-being standards, seeks to establish a comprehensive framework for acoustical design assessment in residential, office, and educational buildings targeting resting and cognitive functions. In conclusion, starting from a global perspective, the study points to the importance of focusing on the local context and acknowledging the challenges and benefits that the context brings for acoustical comfort. The study discusses the importance of context and content in crafting acoustical design criteria, considering the impact of biophilic design and active noise cancellation windows to achieve adaptive acoustic comfort in Singapore's built environment.

Statistical model validation through white noise hypothesis testing in regression analysis and ARIMA models

In the domain of finance and economics, ensuring the validity and dependability of forecasting models is crucial. In this paper, the White Noise Hypothesis Test is elucidated as an essential model validation tool for both the regression and ARIMA models. In the case of regression analysis, there is a need for residual independence and homoscedasticity to confirm that the estimates of the parameters are not biased, that is, the chances of the parameter estimated to be true is high. In the case of an ARIMA model, residuals are checked for the white noise characteristics, and so as to ensure that all the relevant patterns associated with the time series have been detected. The paper uses simulated stock market data and risk management scenarios to demonstrate how these tests enhance model reliability, since when white noise characteristics are ascertained, the residuals are confirmed random and independent. The importance of validating models is discussed in the context of economic forecasting and policy analysis, where the validated models are indispensable for anticipating a market upheaval or to make right economic decisions. Therefore, when white noise test is used to confirm that the model meets the white noise criteria, this improves the credibility of predictions and thus influences strategic decision making in the uncertain environment.

The future of ANSI/ASA S12.2 and room noise criteria

A working group is evaluating the American National Standard, "Criteria for Evaluating Room Noise" (ANSI/ASA S12.2-2019). This presentation will give an overview of our progress and areas of significant proposed change. The goal is to simplify the standard body so that the criteria reflect industry practice. Historical references and less common criteria will be relegated to annexes. Since the beginning of this standard, there has been interest in determining spectral imbalance, temporal variation, and the presence of tones. This talk will briefly mention proposals to quantify these aspects. Feedback from the industry is welcome to minimize the challenges associated with implementing this standard.

HVAC terminal units are too darn loud

This paper discusses three design trends and their implications for heating, ventilation and air conditioning (HVAC) noise: interior designs resulting in exposed utilities in commercial buildings, particularly in flexible seating and open collaboration areas; improving indoor air quality by providing clean and fiber-free airstreams in healthcare, research, or educational facilities; and the use of recently developed sensible-cooling terminal units, also known as dedicated outside air system (DOAS) terminal units. Applying traditional noise control strategies to HVAC systems in these contexts cannot always achieve typical background noise criteria. Design and construction teams must consider alternative strategies which are often relatively extreme in terms of cost, size, and effort. In many cases, the drawbacks of these strategies outweigh their acoustic benefit and so they are not always implemented, resulting in noisy spaces. This paper argues that the design of HVAC terminal units should be refined to reduce generated noise. This would allow customers more flexibility when using terminal units and ultimately reduce noise impacting building occupants across all industries.

Extremely low-vibration experiments with resolutions nanometer range supported on air tables may also require a low-noise environment

The paper reports key results from an extensive diagnostic study examining a room's vibration and acoustic noise environments and their correlation to measurement noise. Vibrations of unknown origin were contaminating research being performed on highly vibration-sensitive apparatus in the basement of a recently completed engineering building. The research involved extensive single‐molecule microscopy requiring resolutions down to 1 nm carried out on an optical table supported on pneumatic legs. Researchers reported that the experimental noise was reported to be of random amplitude less than 40 nm. The problem did not appear to correlate with obvious building or personnel activities. The design vibration and noise criteria for the new space had been VC-E and NC-40, respectively. At the time of the study, the ambient floor vibrations were several classes better; however, the acoustic environment was slightly worse. FRF correlation was calculated between combinations of the tabletop and floor vibrations and airborne sound. The best correlation was between tabletop vibration and airborne sound. The supply air was a significant part of the problem, but the ceiling offered very little attenuation from above. Some of the sound was being generated above the ceiling by HVAC components other than the supply air.

Going to Scale: Broadening Marine Mammal Noise Exposure Criteria for Behavioral Responses

There has been considerable interest in and advances made in both measuring the effects of noise on the behavior of marine mammals and synthesizing results into response thresholds and/or probabilistic functions used in noise criteria. Many of these approaches apply severity 'scales' with presumed gradation of response severity to evaluate specifically identifiable responses in individual or groups of animals exposed in discrete, acute exposure conditions. There has also been considerable and important research looking at disturbance on seasonal or annual timescales for local or regional populations exposed to broader scale or sustained disturbance. However, as yet there has been limited systematic effort to establish behavioral response criteria for these scales. Such criteria, which are certainly needed in many management jurisdictions around the world, will require fundamentally different approaches, metrics, and outputs than acute noise criteria. This paper will consider several possible new approaches and recommend specific steps to begin developing noise criteria for broader, and in some ways more realistic, spatial and temporal scales. Keywords: marine mammals, noise, behavior, response, severity, criteria

Environmental controls of air-conditioned noise with the aid of the Psychoacoustics Perception Scale (PPS)

It is known that an air-conditioning system is an essential component of modern buildings for maintaining good indoor environmental quality. However, the adverse effect due to air-conditioned noise can offset its benefits. Although several noise indices such as Noise Criteria (NC), Noise Rating (NR), Room Criteria (RC), and A-weighted equivalent continuous sound pressure level (LAeq) have been developed to assess the acceptability of indoor noise environments, the noise feature of the environments and its psychological impacts on the occupants are not comprehensively evaluated. Psychoacoustics Perception Scale (PPS) is a psychometric tool to assess the psychological impacts about general judgment (Evaluation, E), sensitivity to the magnitude (Potency, P), and sensation of the temporal and spectral compositions (Activity, A) of noise on occupants. This study aimed to evaluate the air-conditioning building environments by using the traditional noise indices, psychoacoustic metrics, and the PPS. The significant correlations were found between the objective and subjective data. The results of the study provided the useful knowledge on future designs of the environmental controls of air-conditioned noise.

New draft DEGA guideline103-1 for sound protection classes

The DEGA recommendation 103 (DEGA-Empfehlung–Schallschutz im Wohnungsbau und Schallschutzausweis) has been introduced in the year 2009 and includes a classification scheme for dwellings. Seven classes are defined. The classification is based on different criteria for air borne noise, impact noise and other quantities. In 2018, a revised version has been published. Both version relied on classical quantities such as air born sound insulation R’w and impact sound insulation L’n,w. A new version has recently published as a draft DEGA guideline 103-1 (Entwurf zur DEGA-Richtlinie 103-1 “Schallschutz im Wohnungsbau, Teil 1”). In this new draft, the idea of seven classes hae been taken over. The classification not only is based on traditional values such as R’w and L’n,w but also offers the use of the weighed sound level differences DnT,w and weighed standardizes impact sound pressure level L’nT,w. It is suggested to use the later quantities. This dual track approach allows a better design and will lead to a higher acceptance among acousticians and other users. The new draft is presented and will be discussed in relation to other approaches for sound protection in dwellings.

Comparison of facade noise reduction measurement methods: Field results

Many projects require acoustical measurements of facade noise reduction be conducted to verify that Building Code, “green” rating systems (e.g., LEED), or other project interior noise criteria are met. In addition, federally funded airport sound insulation programs in the United States require facade noise reduction measurements be conducted to verify the eligibility of residences receiving sound insulation treatments. Currently, there exists a variety of standards to measure facade noise reduction (e.g., ASTM E966, ISO 16283-3, SAE ARP 6973). These standards employ various measurement methods: artificial exterior noise source, calibrated exterior noise source, line source, etc. In addition, these standards provide guidance on the location of exterior microphones (flush versus near facade) and correction factors to be applied to the data. Recently, a field comparison of three measurement methods was made at multiple residences: artificial exterior noise source, artificial interior noise source, and flush versus near microphone position. This is follow-on research from the National Academies of Science Airport Cooperative Research Project 02-51 and its purpose is to determine whether valid facade noise reduction measurements can be made with the loudspeaker located at the interior of the residence. A comparison of results across the measurement methods will be presented.

The Impact of Fireworks Noise on the Acoustic Climate in Urban Areas

New Year’s Eve is an example of a situation in which urban residents are exposed to an almost continuous and increased noise level from the impulsive sounds sources – fireworks. This custom has become a source of many controversies related to the protection of human and animal health or environmental pollution. However, current legal regulations only slightly affect the subject of noise of fireworks and its harmfulness. Currently, it does not seem possible to completely prohibit the use of fireworks in urban areas, but this does not mean that it is not possible to decrease the degree of their annoyance. The paper consists the issues of identification, analysis and assessment of impulsive noise of fireworks and acoustic climate during New Year’s Eve. Material presented refers to measurements of time series, frequency spectrum and values of noise parameters of selected fireworks. It was presented, among others, that the measured values exceed the criteria for occupational noise (LCpeak), due to the direct hazard of hearing loss, from 1.8 dB at a distance of 25 m and 6.2 dB at a distance of 15 m. Also this work discusses results of impulsive noise measurements of fireworks recorded during New Year’s Eve in years 2016–2017. Material refers to measurements at three measurement points spread over the city of Krakow. Obtained results were compared with typical noise levels for night time in urban area, indicating also the main sources of annoyance and hazard from this type of noise.

An adaptive linear-mode decomposition for effective separation of linear and nonlinear seismic events, ground roll, and random noise

Ground roll and random noise usually mask primary reflections in land seismic data. Different sets of signal processing methods are used to suppress these two noises based on statistical and/or transformation filtering. Among these methods, linear-mode decomposition (LMD) decomposes linear and nonlinear seismic events into amplitude-frequency modulated modes using the Wiener filter. Different combinations of these decomposed linear modes then can be used to represent different seismic events. However, LMD requires predefining the level of decomposition that must be selected carefully to avoid suboptimal binning, which can influence the fidelity of the decomposed seismic modes. To that end, we introduce an adaptive LMD (ALMD) that optimally separates seismic events, ground roll, and random noise. ALMD uses the correlation between the decomposed modes and the input data to determine the decomposition level. Consequently, an optimum decomposition divides the data into linear modes with minimum mixing. In addition, unlike conventional ground roll suppression methods, ALMD does not require estimating the slope or the frequency bandwidth of the ground roll. Moreover, ALMD automates the random noise segregation by separating modes as the signal, noise, and mixed modes, based on the permutation entropy and kurtosis criteria. ALMD iteratively decomposes mixed modes with remnant random noise until a signal or noise criterion is met. Using synthetic and real data examples, we demonstrate that the proposed ALMD is an effective method for separating desired linear and nonlinear events, unwanted ground roll energy, and random noise from the seismic data.

Developing a Comprehensive Construction Noise Specification

As acoustical engineers, we are often asked to develop community noise-related guidelines, regulations, laws, ordinances, and project specifications. This paper will describe the ingredients needed to develop a robust and defensible construction noise specification that is both enforceable and effective. It will be based on the author's past and current experiences developing such specifications, including those used for the Big Dig project in Boston, FHWA's construction noise handbook, the New York City construction noise regulation, as well as dozens of large-scale construction projects across the country. The goals of proactive and reactive noise control and the difference between a performance-based versus a prescriptive-based specification will be explained, community noise criteria will be suggested, and examples will be provided for important clauses in such a specification. Lastly, a listing of "lessons learned" over the decades will be provided.

Deep learning synthesis of cone-beam computed tomography from zero echo time magnetic resonance imaging

Cone-beam computed tomography (CBCT) produces high-resolution of hard tissue even in small voxel size, but the process is associated with radiation exposure and poor soft tissue imaging. Thus, we synthesized a CBCT image from the magnetic resonance imaging (MRI), using deep learning and to assess its clinical accuracy. We collected patients who underwent both CBCT and MRI simultaneously in our institution (Seoul). MRI data were registered with CBCT data, and both data were prepared into 512 slices of axial, sagittal, and coronal sections. A deep learning-based synthesis model was trained and the output data were evaluated by comparing the original and synthetic CBCT (syCBCT). According to expert evaluation, syCBCT images showed better performance in terms of artifacts and noise criteria but had poor resolution compared to the original CBCT images. In syCBCT, hard tissue showed better clarity with significantly different MAE and SSIM. This study result would be a basis for replacing CBCT with non-radiation imaging that would be helpful for patients planning to undergo both MRI and CBCT.

Optimizing building designs for mechanical equipment tones

Poor noise conditions in buildings often involve tones from mechanical equipment. However, noise criteria generally neglect tones due to (1) lack of agreement on what constitutes a tone; (2) lack of acoustical data from equipment and noise treatment manufacturers in ⅓-octave or better resolution; and (3) limited design tools and resources to act on detailed information even if it were available. Since building designs also cannot be tested and optimized prior to production like cars, appliances and other mass-produced products, problems can remain hidden until final occupancy. Therefore, design strategies usually involve a variety of conservative and/or safe “best practice” approaches that avoid certain space adjacencies or equipment types altogether, often at significant cost. This is unsurprising when considering the complexity and risks associated with many tonal noise control problems, often including sound-structure interaction. However, a path for innovation exists through wider use of frequency-response-function (FRF) measurements (or measurements with otherwise known inputs) and the ability to analyze, share and incorporate the findings into source-path-receiver designs. This presentation will propose steps to gather, standardize and distribute such information and use case studies to illustrate how this is an enormous opportunity for optimizing building designs for cost and performance.

The benefits and challenges of the collaborative for high performing schools acoustical performance requirements in Colorado K–12 schools

The Collaborative for High Performing Schools (CHPS) is a national organization that provides technical resources for school design, construction, operations, and maintenance standards. It also provides a verification program, which includes an acoustical performance prerequisite and enhanced acoustical performance credits. This presentation will explore the benefits and challenges of the various acoustical prerequisite and credit requirements, including reverberation time (RT) targets, background noise criteria, and interior and exterior sound isolation, through the design and construction of several projects in Colorado. By comparing the theoretical benefits to the practical applications of these requirements, improvements to constructibility are proposed. Additionally, the financial impact of pursuing a CHPS certification is examined, especially for school districts with limited financial resources.

Predicting tonal noise problems in HVAC systems

Current indoor noise criteria for occupied spaces in buildings can be found in Table 1 of the 2019 ASHRAE Applications Handbook. Table 1 of this handbook provides design guidelines for recommended NC, RC, dBA, and dBC ratings for a wide variety of interior spaces, but there is nothing in the table or the table notes that mentions the issue of audible tones in the background noise spectrum. There is a comment in the handbook text that essentially states that ideally, there should be no audible tones such as hum or whine. However, no guidance is provided as to how to predict or even measure (after the fact) if an audible tone is present. This presentation provides some guidance as to how a person might go about predicting the presence of an audible tone in the background noise of the HVAC system, including an example of a fully installed system.

Evaluating tonal noise in the outdoor environment

Most outdoor noise criteria are based on the overall A-weighted sound pressure level evaluated at one or more location(s) on the receiving property. The maximum allowable sound pressure level is usually based on the zoning or actual use of the source and receiving properties. The referenced levels are often the Leq and/or the Lmax measured over a defined time interval, although the L(n) percentile statistical levels are sometimes specified. It is a well-known fact in the acoustics community that broadband sound at a given level is less annoying than sound with strong tonal components at the same sound pressure level. As a result, many state and local governments have included tonal penalties in their environmental noise ordinances to help compensate for this tonal annoyance factor. This presentation identifies several state and prominent local governments that have imposed such a penalty and how the government has elected to assess the presence of a tone that would warrant such a penalty.

Assessment of hearing loss risk due to impact noise in industrial environments

Impact noises are often found in industrial environments and they are predominant in mining, construction, factories, workshops, and shipyards. It is well-known that impact noises are more likely to cause noise-induced hearing loss than continuous noise of equal energy. Impulse noises are characterized by their high intensity over a short period of time and many countries have defined impulse noise exposure limits and criteria in occupational settings. They are based on the sound level measurements made using standard sound pressure level meters and dosemeters. However, because of their metrological limitations, it is not appropriate to use these instruments when dealing with such high peak levels and short duration times. Extensive research on hearing damage produced by impulse noise generated by firearms has been presented, mainly on police and military personnel. These studies have led to damage risk criteria contained in various versions of the standard MIL-STD-1474. Although industrial noises can reach similar peak sound pressure levels, not many results have been published on the subject. In this work, several common sources of industrial impact noise were measured in-situ, at the worker locations, using a specialized system equipped with high-dynamic-range microphones and a very high data acquisition rate. The signals were post-processed to obtain the main metrics defined for impulse noise exposure assessment. Then, occupational hearing loss risk was estimated using different criteria. It is shown that many common industrial processes reported a very high risk of impulsive noise to human hearing.

Can advanced edge enhancement software improve image quality to visualise tubes, catheters and wires in digital chest radiographs?

IntroductionThis study aimed to test whether Advanced Edge Enhancement (AEE) software could improve the localisation of tubes, catheters or wires, while also affecting the overall image quality in chest x-rays (CXR). MethodsIn total, 50 retrospective CXRs were included. All images were obtained utilising the Canon X-ray system (CANON/Arcoma Precision T3 DR System, Canon Europe, Amsterdam, NL) with a CXDI-810C wireless detector. A clinical image, plus three additional AEE algorithms were applied using post processing (two intensity variations 1 and 4) on all CXRs totalling 350 different images. Three radiologists evaluated the images using a subjective Absolute Visual Grading Analysis (VGA). The clinical images used in post processing were not applied as reference in the analysis. Each radiologist graded the images separately in a randomized order, with a score of three indicating suitability for diagnostic assessment. ResultsThe three AEE algorithms contributed to an overall improvement (average 16–49%) in visualisation of tube, catheter or wire on CXR images. The Mann–Whitney U tests showed a statistically significant (p < 0.05) improvement in contrast resolution and sharpness, indicating an increased ability to differentiate tubes, wires or catheters tips from surrounding tissues. For the noise criterion, not applying any AEE algorithm showed a significantly higher homogeneity in soft tissue (p < 0.001), reducing the ability to visualise soft tissue. The high-intensity catheter algorithm was the only algorithm to achieve a statistically significant (p = 0.017) increase in the ability to differentiate pulmonary tissues of similar density. ConclusionAn overall improvement in the visualisation of tube, catheter and wire placement was obtained using the three AEE-algorithms. The bone and catheter algorithms showed the highest consistency, with the small structure algorithm underperforming in resolution and low contrast resolution. In general, image noise increased regardless of algorithm type or applied intensity. The AEE-algorithms should therefore be seen as a supplementary tool to the clinical image protocol, while having the potential to improve image quality to specific clinical situations. Implications for practiceAEE filtered images appear to be a supplement to the current practice of using CXRs in the diagnosis in placement of catheters, tubes and wires in the chest region. The use of AEE-algorithms has the potential to improve the daily work in clinical practice, which serves the basis for further investigation of its effect on radiographic practices.

Influence of SNR on the speech perception of incomplete hearing people

In the past, people received an education based on the school curriculum, which indicated that the school age was restricted to people of ages from 5 to 24. However, early and lifelong education has further become crucial in the modern age, which means that education is available from preschool to the elderly. However, the ability to listen clearly is immature in preschoolers and generally deteriorated among the elderly compared with conventional school-age populations. Therefore, certain age groups exhibit a declined ability to perceive speech as their auditory characteristics differ from school-age students, which in this paper are referred to as people with incomplete hearing. This paper conducted an early study to establish the learning background noise criteria for people with incomplete hearing. To identify the differences in environmental speech perception abilities, variations were made to the background noise, and speech intelligibility tests were performed. The targeted ages for the experiment were three groups of 20 people or more respectively, an average age of 9.6 years for children, an average age of 24.4 years for adults, and an average age of 67.7 years for elderly. The smaller the signal to noise ratio (SNR), the lower is the percentage of correct answers in the speech intelligibility test. In general, the groups with incomplete hearing had a lower percentage of correct answers in the speech intelligibility test than the normal hearing adult group. Thus, the proper SNR for an educational space for people with incomplete hearing was determined to be 20 dB for the Elderly group and 15 dB for the children group.