Acceptable Noise Research Articles

Correction: Loudness as a Cue for Acceptable Noise Levels.

Correction: Loudness as a Cue for Acceptable Noise Levels.

Inexact fuzzy integer chance constraint programming approach for noise control within an urban environment

This article introduces an inexact fuzzy integer chance constraint programming (IFICCP) approach for identifying noise reduction strategy under uncertainty. The IFICCP method integrates the interval programming and fuzzy chance constraint programming approaches into a framework, which is able to deal with uncertainties expressed as intervals and fuzziness. The proposed IFICCP model can be converted into two deterministic submodels corresponding to the optimistic and pessimistic conditions. The modelling approach is applied to a hypothetical control measure selection problem for noise reduction. Results of the case study indicate that useful solutions for noise control practices can be acquired. Three acceptable noise levels for two communities are considered. For each acceptable noise level, several decision alternatives have been obtained and analysed under different fuzzy confidence levels, which reflect the trade-offs between environmental and economic considerations.

Accounting for patient size in the optimization of dose and image quality of pelvis cone beam CT protocols on the Varian OBI system.

The purpose of this study was to develop size-based radiotherapy kilovoltage cone beam CT (CBCT) protocols for the pelvis. Image noise was measured in an elliptical phantom of varying size for a range of exposure factors. Based on a previously defined "small pelvis" reference patient and CBCT protocol, appropriate exposure factors for small, medium, large and extra-large patients were derived which approximate the image noise behaviour observed on a Philips CT scanner (Philips Medical Systems, Best, Netherlands) with automatic exposure control (AEC). Selection criteria, based on maximum tube current-time product per rotation selected during the radiotherapy treatment planning scan, were derived based on an audit of patient size. It has been demonstrated that 110 kVp yields acceptable image noise for reduced patient dose in pelvic CBCT scans of small, medium and large patients, when compared with manufacturer's default settings (125 kVp). Conversely, extra-large patients require increased exposure factors to give acceptable images. 57% of patients in the local population now receive much lower radiation doses, whereas 13% require higher doses (but now yield acceptable images). The implementation of size-based exposure protocols has significantly reduced radiation dose to the majority of patients with no negative impact on image quality. Increased doses are required on the largest patients to give adequate image quality. The development of size-based CBCT protocols that use the planning CT scan (with AEC) to determine which protocol is appropriate ensures adequate image quality whilst minimizing patient radiation dose.

Application of a Monte Carlo solar radiative transfer modelin the McICA framework

Large‐scale atmospheric models (LSAMs) that utilize the Monte Carlo Independent Column Approximation (McICA) have, thus far, paired McICA only with two‐stream approximations (TSAs) of the radiative transfer equation. In this study, the short‐wave TSA is exchanged for a Monte Carlo (MC) photon transport model. More than 44 000 domains of cloud properties retrieved from A‐Train satellite data, each measuring 256 km in length, were used to assess the noise characteristics of TSA‐ and MC‐based McICA models. It appears as though application of an MC algorithm in McICA will be both beneficial and tractable for LSAMs. This is because known levels of acceptable radiative noise produced by TSA‐based McICAs can be achieved with small numbers of MC photons. The greatest concern with the TSA McICA has been noise associated with heating rates for cloudy layers. But with as few as 500–1000 photons per simulation, the MC McICA reduces cloudy layer heating rate errors by typically ∼20%. Furthermore, since MC models can utilize detailed descriptions of cloud particle scattering phase functions and TSAs use only corresponding asymmetry parameters, TSA‐based McICAs, on average, overestimate all‐sky top‐of‐atmosphere reflected flux density at small solar zenith angles θ0 by ∼3 W m−2 and underestimate it at large θ0 by ∼1 W m−2; vice versa for surface net flux density. Systematic biases such as these are important when attempting to balance an LSAM's energy budgets and when making detailed estimates of radiative forcings due to anthropogenic activities.

Measurement of Acceptable Noise Level with Background Music.

Background and ObjectivesAcceptable noise level (ANL) is a measure of the maximum background noise level (BNL) that a person is willing to tolerate while following a target story. Although researchers have used various sources of target sound in ANL measures, a limited type of background noise has been used. Extending the previous study of Gordon-Hickey & Moore (2007), the current study determined the effect of music genre and tempo on ANLs as possible factors affecting ANLs. We also investigated the relationships between individual ANLs and the familiarity of music samples and between music ANLs and subjective preference.Subjects and MethodsForty-one participants were seperated into two groups according to their ANLs, 29 low-ANL listeners and 12 high-ANL listeners. Using Korean ANL material, the individual ANLs were measured based on the listeners' most comfortable listening level and BNL. The ANLs were measured in six conditions, with different music tempo (fast, slow) and genre (K-pop, pop, classical) in a counterbalanced order.ResultsOverall, ANLs did not differ by the tempo of background music, but music genre significantly affected individual ANLs. We observed relatively higher ANLs with K-pop music and relatively lower ANLs with classical music. This tendency was similar in both low-ANL and high-ANL groups. However, the subjective ratings of music familiarity and preference affected ANLs differently for low-ANL and high-ANL groups. In contrast to the low-ANL listeners, the ANLs of the high-ANL listeners were significantly affected by music familiarity and preference.ConclusionsThe genre of background music affected ANLs obtained using background music. The degree of music familiarity and preference appears to be associated with individual susceptibility to background music only for listeners who are greatly annoyed by background noise (high-ANL listeners).

Phase-locked loop stability based on stochastic bounds

In this paper we study the stability of a phase-locked loop (PLL) in the presence of noise. We represent the noise as Brownian motion and model the circuit as a nonlinear stochastic differential equation, with the noise lumped at the phase detector input. We show that for the PLL, the theory of asymptotics of singular diffusions can be applied and we use this theory to develop a new figure of merit which we call a stability margin. The stability margin provides easily computable bounds on the acceptable noise levels for which stability is guaranteed. Through simulation, we show that such a sufficient bound provides a realistic prediction for PLL stability.

Aeroacoustic Analysis of a High-Speed Open Rotor

Owing to their inherent fuel efficiency, there is renewed interest in developing open rotor propulsion systems that are both efficient and quiet. The major contributor to the overall noise of an open rotor system is the propulsor noise, which is produced as a result of the interaction of the airstream with the counter-rotating blades. Prediction of the propulsor noise is, therefore, a necessary ingredient in any approach for designing low-noise open rotor systems that can meet community noise regulations and have acceptable cabin noise levels. To that end, there has been a resurgence of activities in the aeroacoustic modeling of open rotors in recent years. While direct numerical simulations are gaining traction, the bulk of existing prediction capability resides in hybrid approaches in which the aerodynamics of the open rotor system is computed via CFD and is used as input in some appropriate “linear” acoustic model for computing the open rotor noise. At NASA the focus has been on assessing the utility of hybrid approaches for accurately predicting the open rotor tone spectra with an emphasis on the understanding of the role of the various underlying mechanisms of noise generation and their relative importance at different operating conditions. Using high-fidelity aerodynamic simulations of a benchmark (non-proprietary) open rotor blade set, together with acoustic models based on a high-blade-count asymptotic approximation of the Ffowcs-Williams Hawkings equation, tone noise predictions for a number of configurations have been carried out. These aerodynamic and acoustic predictions have been compared with wind tunnel measurements of the benchmark open rotor blade set to establish the capabilities and the limitations of the hybrid approaches. The results suggest that while predicting the absolute spectral levels is difficult, the noise trends are reasonably well predicted by such hybrid approaches at a reasonable overall computational cost.

Predicting the Sensitivity of Multiscale Coarse-Grained Models to their Underlying Fine-Grained Model Parameters.

The sensitivity of a coarse-grained (CG) force field to changes in the underlying fine-grained (FG) model from which it was derived provides modeling insight for improving transferability across interaction parameters, transferability across temperature, and the calculation of thermodynamic derivatives. Methods in the literature, such as multi-trajectory finite differences and reweighted finite differences, are either too computationally demanding to calculate within acceptable noise tolerances or are too biased for practical accuracy. This work presents a new reweighting-free, single-simulation formula that allows for practical, high signal-to-noise calculations of CG model sensitivity with respect to FG model interaction parameters and thermodynamic state points. This formula, the self-consistent basis (SCB) single point formula, determines the many-body sensitivity in a single step by approximating the derivative of the many-body potential projected onto the same set of trial functions as the sensitivity. A related diagnostic formula also derived in this paper is the self-consistent iterative (SCI) single point formula, which is useful for identifying the importance of many-body sources of error and verifying CG representability of observables. The SCI formula determines the many-body sensitivity iteratively via a series of partially self-consistent, variational approximations to the complete many-body sensitivity. The new, computationally efficient SCB formula shows substantially less noise than previous methods when applied to single site methanol and solvent-free sodium chloride CG models, though bias can remain a problem. It represents a novel method for calculating alchemical transferability across interaction parameters at low computational cost and with high fidelity, and the results point to new understanding of the current limits of CG model transferability.

An evaluation of the performance of two binaural beamformers in complex and dynamic multitalker environments

Objective: Binaural beamformers are super-directional hearing aids created by combining microphone outputs from each side of the head. While they offer substantial improvements in SNR over conventional directional hearing aids, the benefits (and possible limitations) of these devices in realistic, complex listening situations have not yet been fully explored. In this study we evaluated the performance of two experimental binaural beamformers. Design: Testing was carried out using a horizontal loudspeaker array. Background noise was created using recorded conversations. Performance measures included speech intelligibility, localization in noise, acceptable noise level, subjective ratings, and a novel dynamic speech intelligibility measure. Study sample: Participants were 27 listeners with bilateral hearing loss, fitted with BTE prototypes that could be switched between conventional directional or binaural beamformer microphone modes. Results: Relative to the conventional directional microphones, both binaural beamformer modes were generally superior for tasks involving fixed frontal targets, but not always for situations involving dynamic target locations. Conclusions: Binaural beamformers show promise for enhancing listening in complex situations when the location of the source of interest is predictable.

The Effects of Audiovisual Stimulation on the Acceptance of Background Noise.

Previous examinations of noise acceptance have been conducted using an auditory stimulus only; however, the effect of visual speech supplementation of the auditory stimulus on acceptance of noise remains limited. The purpose of the present study was to determine the effect of audiovisual stimulation on the acceptance of noise in listeners with normal and impaired hearing. A repeated measures design was utilized. A total of 92 adult participants were recruited for this experiment. Of these participants, 54 were listeners with normal hearing and 38 were listeners with sensorineural hearing impairment. Most comfortable levels and acceptable noise levels (ANL) were obtained using auditory and auditory-visual stimulation modes for the unaided listening condition for each participant and for the aided listening condition for 35 of the participants with impaired hearing that owned hearing aids. Speech reading ability was assessed using the Utley test for each participant. The addition of visual input did not impact the most comfortable level values for listeners in either group; however, visual input improved unaided ANL values for listeners with normal hearing and aided ANL values in listeners with impaired hearing. ANL benefit received from visual speech input was related to the auditory ANL in listeners in each group; however, it was not related to speech reading ability for either listener group in any experimental condition. Visual speech input can significantly impact measures of noise acceptance. The current ANL measure may not accurately reflect acceptance of noise values when in more realistic environments, where the signal of interest is both audible and visible to the listener.

Speech Recognition at the Acceptable Noise Level.

The acceptable noise level (ANL) has been proposed as a prehearing aid fitting measure that could be used for hearing aid selection and counseling purposes. Previous work has demonstrated that a listener's ANL is unrelated to their speech recognition in noise abilities. It is unknown what criteria a listener uses when they select their ANL. To date, no research has explored the amount of speech recognized at the listener's ANL. To examine the amount of speech recognized at the listener's ANL to determine whether speech recognition in noise is utilized as a factor for setting ANL. A descriptive quasi-experimental study was completed. For all listeners, ANL was measured and speech recognition in noise was tested at ANL and at two additional signal-to-noise ratio (SNR) conditions based on the listener's ANL (ANL + 5 and ANL - 5). Forty-four older adults served as participants. Twenty-seven participants had normal hearing and seventeen participants had mild to moderately-severe, symmetrical, sensorineural hearing loss. Acceptance of noise was calculated from the measures of most comfortable listening level and background noise level. Additionally, speech recognition in noise was assessed at three SNRs using the quick speech-in-noise test materials. A significant interaction effect of SNR condition and ANL group occurred for speech recognition. At ANL, a significant difference in speech recognition in noise was found across groups. Those in the mid and high ANL groups had excellent speech recognition at their ANL. Speech recognition in noise at ANL decreased with ANL category. For listeners with mid and high ANLs, speech recognition appears to play a primary role in setting their ANL. For those with low ANLs, speech recognition may contribute to setting their ANL; however, it does not appear to be the primary determiner of ANL. For those with very low ANLs, speech recognition does not appear to be significant variable for setting their ANL.

Study on the Acceptable Noise Level (ANL) in Patients with Tinnitus and Hearing Loss and Association with Self-reported Subjective Questionnaire

Study on the Acceptable Noise Level (ANL) in Patients with Tinnitus and Hearing Loss and Association with Self-reported Subjective Questionnaire

Simultaneous evaluation of vascular morphology, blood volume and transvascular permeability using SPION-based, dual-contrast MRI: imaging optimization and feasibility test.

Exploiting ultrashort-T(E) (UTE) MRI, T1-weighted positive contrast can be obtained from superparamagnetic iron oxide nanoparticles (SPIONs), which are widely used as a robust T2-weighted, negative contrast agent on conventional MR images. Our study was designed (a) to optimize the dual-contrast MRI method using SPIONs and (b) to validate the feasibility of simultaneously evaluating the vascular morphology, blood volume and transvascular permeability using the dual-contrast effect of SPIONs. All studies were conducted using 3 T MRI. According to numerical simulation, 0.15 mM was the optimal blood SPION concentration for visualizing the positive contrast effect using UTE MRI (T(E) = 0.09 ms), and a flip angle of 40° could provide sufficient SPION-induced enhancement and acceptable measurement noise for UTE MR angiography. A pharmacokinetic study showed that this concentration can be steadily maintained from 30 to 360 min after the injection of 29 mg/kg of SPIONs. An in vivo study using these settings displayed image quality and CNR of SPION-enhanced UTE MR angiography (image quality score 3.5; CNR 146) comparable to those of the conventional, Gd-enhanced method (image quality score 3.8; CNR 148) (p > 0.05). Using dual-contrast MR images obtained from SPION-enhanced UTE and conventional spin- and gradient-echo methods, the transvascular permeability (water exchange index 1.76-1.77), cerebral blood volume (2.58-2.60%) and vessel caliber index (3.06-3.10) could be consistently quantified (coefficient of variation less than 9.6%; Bland-Altman 95% limits of agreement 0.886-1.111) and were similar to the literature values. Therefore, using the optimized setting of combined SPION-based MRI techniques, the vascular morphology, blood volume and transvascular permeability can be comprehensively evaluated during a single session of MR examination.

Acceptance noise level: effects of the speech signal, babble, and listener language.

The acceptable noise level (ANL) measure has gained much research/clinical interest in recent years. The present study examined how the characteristics of the speech signal and the babble used in the measure may affect the ANL in listeners with different native languages. Fifteen English monolingual, 16 Russian-English bilingual, and 24 Spanish-English bilingual listeners participated. The ANL was obtained in eight conditions varying in the language of the signal (English and Spanish), language of the babble (English and Spanish), and number of talkers in the babble (4 and 12). Test conditions were randomized across listeners. The ANL for each condition was based on a minimum of two trials. Russian-English bilinguals yielded higher ANLs than other listeners; the intergroup difference of 4-5 dB was statistically and clinically significant. Spanish signals yielded significantly higher ANLs than English signals, but this difference of 0.5 dB was clinically negligible. The language and composition of the babble had a significant effect on Russian-English bilinguals, who yielded higher ANLs with the Spanish than English 12-talker babble. The above findings do not fully support the notion that the ANL is language- and population-independent. Clinicians should be aware of possible effects on ANL measures due to listeners' linguistic/cultural background.

Practical dc SQUID system: Devices and electronics

In order to set up a liquid helium-cooled practical dc SQUID system with acceptable noise figure, we employ a weakly damped dc SQUID with a large flux-to-voltage transfer coefficient ∂V/∂Ф in a direct readout scheme (DRS) without flux modulation. Two preamplifiers are utilized: (1) AD 797 for a so-called “single chip readout electronics” (SCRE); (2) 6 parallel-connected bipolar transistors (PCBT). The latter reduces the preamplifier voltage noise Vn but increases its current noise In, which plays a leading role in the system low-frequency noise. We introduce a current feedback circuit (CFC) consisting of an inductor Li coupled to the SQUID with mutual inductance Mi to improve the noise performance. In this work, the preamplifier In contribution and CFC are analyzed. To evaluate the In suppression with CFC, two criteria are presented. Furthermore, we establish a dimensionless parameter ξ to describe CFC quantitatively. The system noise is compared with and without CFC using the two preamplifiers. For a dc SQUID with a loop inductance of 350pH, an intrinsic noise of about 5μФ0/√Hz and a corner frequency at 2Hz are measured using PCBT with CFC.

A CMOS readout circuit for microstrip detectors

In this work, we present the design and the results of a CMOS analog channel for silicon microstrips detectors. The readout circuit was initially conceived for the outer layers of the SuperB silicon vertex tracker (SVT), but can serve more generally other microstrip-based detection systems. The strip detectors considered show a very high stray capacitance and high series resistance. Therefore, the noise optimization was the first priority design concern. A necessary compromise on the best peaking time to achieve an acceptable noise level together with efficiency and timing accuracy has been investigated. The ASIC is composed by a preamplifier, shaping amplifier and a Time over Threshold (T.o.T) block for the digitalization of the signals. The chosen shaping function is the third-order semi-Gaussian function implemented with complex poles. An inverter stage is employed in the analog channel in order to operate with signals delivered from both p and n strips. The circuit includes the possibility to select the peaking time of the shaper output from four values: 250 ns, 375 ns, 500 ns and 750 ns. In this way, the noise performances and the signal occupancy can be optimized according to the real background during the experiment. The ASIC prototype has been fabricated in the 130 nm IBM technology which is considered intrinsically radiation hard. The results of the experimental characterization of a produced prototype are satisfactorily matched with simulation.

Application of noise guidance to the assessment of industrial noise with character on residential dwellings in the UK

British Standards are used to assist the assessment of noise impact from new or existing sources and assist judgements of acoustic acceptability. Standards may include provision for the assessment of noise with character whilst others are limited to anonymous noise. Noise guidance designed for the assessment of anonymous/characterless noise appears increasingly used to justify acceptable noise impact from industrial noise with character (identifiable site noise). The result is an inappropriate comparison with guideline values that ignore noise character and context in the assessment of noise acceptability at dwellings. This technical note conducts a critical review of noise guidance and considers four sources of industrial noise with character. Preliminary comparisons of analysed noise data with the World Health Organization Guidelines for Community Noise (WHO 1999), World Health Organization Night Noise Guidelines for Europe (WHO 2009), BS8233 2014 Guidance on sound insulation and noise reduction for buildings (BS8233) and BS4142 2014 Methods for rating and assessing industrial and commercial sound (BS4142) demonstrate guidance designed for anonymous noise significantly understates the impact of industrial noise with character on dwellings when compared to noise guidance for rating and assessing industrial sound accompanied with context based observations of noise impact.

Comparison of sound insulation of windows with double glass units

Level of external noise grows every day in modern cities. New buildings usually have large windows or the whole areas of glass walls therefore protection from external noise is very important. Façade with good sound insulation properties is required to ensure acceptable internal noise level. Sound insulation of façade mainly depends from sound insulation properties of insulated glass unit (IGU). Different IGU with double, triple or even tetra glass could be used. In this paper is presented experimental study of window with three different type double glass units: 1 – two ordinary glass; 2 – one glass ordinary second one laminated; 3 – two laminated glass. The experimental results showed that sound reduction index (R) values are lower than 30dB below frequency of 315Hz (first type IGU), 250Hz (second type IGU) and 125Hz (third type IGU); sound reduction index (R) exceeds 45dB above frequency of 4000Hz (first type IGU), 2500Hz (second type IGU) and 1600Hz (third type IGU).

Design of Mini Wind Tunnel Based on Coanda Effect

An experimental investigation and CFD treatment were employed to design mini-wind tunnel based on Coanda effect for model tests and basic research. The inlet source flow is efficiently creating smooth steady airflow with acceptable noise, achieving the possibility of placing the test target closer to the source of flow with reasonable estimates of turbulence intensity. The design aims at achieving flow uniformity in the working section midplane, preventing separation in the contraction and minimizing the boundary–layer thickness. Intensive measurements after construction demonstrate the significance of the design process and validate the CFD predictions. The results are represented in graphic form to indicate the aspects of the contraction ratio. The numerical and experimental results show the uniformity of velocity distribution inside the working section. Tracing of separation and backflow is crucial allowing a variety of realistic demonstrations to be performed. The numerical solution provides a powerful tool to demonstrate the rate of boundary–layer growth inside the working section and validate against the empirical correlations with insignificant wall–friction drag. Assessment study to address large–scale wind tunnel based on coanda effect would be considered.

Are the noise levels acceptable in a built environment like Hong Kong?

Governments all over the world have enacted environmental noise directives and noise control ordinances/acts to protect tranquility in residential areas. However, there is a lack of literature on the evaluation of whether the Acceptable Noise Levels (ANLs) stipulated in the directive/ordinance/act are actually achievable. The study aimed at measuring outdoor environmental noise levels in Hong Kong and identifying whether the measured noise levels are lower than the stipulated ANLs at 20 categories of residential areas. Data were gathered from a territory-wide noise survey. Outdoor noise measurements were conducted at 203 residential premises in urban areas, low-density residential areas, rural areas, and other areas. In total, 366 daytime hourly Leq outdoor noise levels, 362 nighttime hourly Leq outdoor noise levels, and 20 sets of daily, that is, 24 Leq,1-h outdoor noise levels were recorded. The mean daytime Leq,1-h values ranged 54.4-70.8 dBA, while the mean nighttime Leq,1-h values ranged 52.6-67.9 dBA. When the measured noise levels were compared with the stipulated ANLs, only three out of the 20 categories of areas had outdoor noise levels below ANLs during daytime. All other areas (and all areas during nighttime) were found to have outdoor noise levels at or above ANLs.