Detailed Noise Research Articles

Speed dependence, sources, and directivity of small vessel underwater noise.

Small vessels (<10 m) radiate underwater noise in sensitive coastal environments, but there is insufficient knowledge of their noise radiation. Through detailed measurements of seven small boats and a jet ski in a shallow water environment on the Swedish west coast, this study presents results on the speed dependence of small vessel underwater noise, its sources, and its directivity. For vessels with planing hulls, broadband source levels increase with speed until planing is attained. When planing, source level dependence on speed is weak. A detailed noise source analysis of one vessel showed that at low speed, tonals from the engine dominate the noise radiation, whereas at higher speeds, propeller tonals and broadband noise dominate. Noise radiation into different horizontal angles shows little angle dependence, and noise levels relative to the closest point of approach show a similar pattern across all investigated vessels. Received noise levels at approximately 100 m range are not high enough to cause hearing impairment in marine animals, but fast-moving small vessels may cause behavioural reactions or stress responses across several marine animal groups.

A Prediction Method for City Traffic Noise Based on Traffic Simulation under a Mixed Distribution Probability

Predicting and assessing urban traffic noise is crucial for environmental management. This paper establishes a traffic noise simulation method based on microscopic traffic simulation, utilizing a traffic simulation under a mixed distribution probability combining normal and exponential distributions. This method integrates a single-vehicle noise prediction model to compute the spatial distribution of noise. Comparison with empirical data demonstrates that the proposed model effectively predicts the level of traffic noise. The accuracy of the model is validated through comparison with measured data, showing minimum and maximum errors of 3.60 dB(A) and 4.37 dB(A), respectively. Additionally, the noise spatial results under microscopic traffic models are compared with those under line source models, revealing that the proposed model provides a more detailed and realistic noise spatial distribution. Furthermore, the noise variation patterns between stable and time-varying traffic flows are investigated. Results indicate that noise levels fluctuate under stable traffic flow, whereas under time-varying traffic flow, noise values exhibit a stepped change.

Comparison of amount of noise and elimination strategies for noise in neonatal intensive care units of government and private hospitals in the Jodhpur district of India.

With technological advancement, neonatal intensive care units (NICUs) have become noisier than ever. Studies have shown the detrimental effects of increasing noise in NICU on growing pre-term and sick neonates. The present study aimed primarily to compare the amount of noise in NICUs of private and government hospitals. The secondary aim was to compare the strategies adopted by these hospitals to control the detrimental effects of noise on newborns. A detailed noise survey was conducted in the NICUs of two private and two government hospitals in the Jodhpur district, India. The noise survey was performed for a duration of 48 h using "Sound Ear 3-300" noise meters. The analyses were measured in Leq (equivalent continuous sound level) A-weighted decibels (dBA). The extracted data analysis revealed that the noise measured was in the range of 61.62-82.32 dBA in four NICUs of the district. The results also revealed a statistically significant difference between the NICU noise of private and government hospitals. The levels of alarming sounds differed between the hospitals with a general trend of lesser alarming sounds in private hospitals. The major differences in strategies adopted were that both private hospitals had a protocol to purposely reduce levels of alarming sounds when heard, and purposely limited the number of staff present in certain areas of the NICU, which were correlated with reduced sound compared to the government hospitals. Strategies like these require no additional cost to make drastic changes in the average noise measured.

Charge-parity switching effects and optimisation of transmon-qubit design parameters

Enhancing the performance of noisy quantum processors requires improving our understanding of error mechanisms and the ways to overcome them. A judicious selection of qubit design parameters plays a pivotal role in improving the performance of quantum processors. In this study, we identify optimal ranges for qubit design parameters, grounded in comprehensive noise modeling. To this end, we also analyze the effect of a charge-parity switch caused by quasiparticles on a two-qubit gate. Due to the utilization of the second excited state of a transmon, where the charge dispersion is significantly larger, a charge-parity switch will affect the conditional phase of the two-qubit gate. We derive an analytical expression for the infidelity of a diabatic controlled-Z gate and see effects of similar magnitude in adiabatic controlled-phase gates in the tunable coupler architecture. Moreover, we show that the effect of a charge-parity switch can be the dominant quasiparticle-related error source of a two-qubit gate. We also demonstrate that charge-parity switches induce a residual longitudinal interaction between qubits in a tunable-coupler circuit. Furthermore, we introduce a performance metric for quantum circuit execution, encompassing the fidelity and number of single- and two-qubit gates in an algorithm, as well as the state preparation fidelity. This comprehensive metric, coupled with a detailed noise model, enables us to determine an optimal range for the qubit design parameters, as confirmed by numerical simulation. Our systematic analysis offers insights and serves as a guiding framework for the development of the next generation of transmon-based quantum processors.

Design, assembly and testing of an upgraded aeroacoustics wind tunnel facility

The Aeroacoustics Laboratory in the Department of Aerospace Engineering at Penn State currently serves several areas of experimental research. Most notable in the laboratory is the Anechoic Chamber of which the Aeroacoustics Wind Tunnel is an integral part. In recent years the dominant areas of research have included model aircraft exhaust jets and model rotors for helicopter applications involving detailed noise experiments. In the jet noise area, the applications have included aircraft in both flyover and take-off configurations. In the flyover application the air flow surrounding the exhaust jet has a significant effect on the radiated noise and must be simulated to produce experimental results that will be most useful in preliminary design of noise suppression applications. The Aeroacoustics Wind Tunnel at Penn State serves the purpose for this simulation. During aircraft take-off, the aircraft airspeed is in a range exceeding 250 ft per second, or Mach number of over M = 0.22. In the years preceding 2022, the velocity of the free jet flow of the Penn State facility was limited to less than 200 ft/sec. This paper reports on a project to design upgrades to the existing wind tunnel to improve the test section flow velocity to values closer to the 250 ft/sec target. The approach began with a preliminary design of the return flow ducting to convert the open jet, open return wind tunnel to a closed return tunnel. The concept is to make use of the flow energy in the exhaust of the tunnel to boost the input energy to the inlet fan that drives the flow to the test section. An integral part of the preliminary design involved making use of an upgraded flow analysis computer code to predict the gain in test section velocity of the new facility. For the available horsepower of two fans in the facility, the configurations of the existing and upgraded wind tunnel were entered into this analysis code based on a quasi-one-dimensional formulation. The code included empirical data formulated to include the various shapes of the components of the tunnels. The relative flow velocities in each section used simple incompressible continuity to calculate all velocities in the component sections. The average dynamic pressure in each section is calculated from the flow (constant) density and the velocity squared. Each section had a non-dimensional pressure loss parameter calculated from empirical data (from the relevant literature). The basic code (using the Excel algorithms) was based on a predictor-corrector concept in which the calculation was initialized with the estimated velocity and pressure of the flow at the entrance to the test section. The loss in each following section is estimated to determine the loss in the total pressure and the cumulated loss compared to the gains made at the two fans in the circuit. The initial guess is adjusted based on the total pressure value at the end of the circuit. During the related experiments, measurements of the total and dynamic pressure were performed at several joints between sections and compared to the values predicted in the analysis code. Various settings of the horsepower of the drive fans were used and the results were compared to flow measurements for the tunnel configurations (predominantly for the open return and closed return tunnel setups available before and after the upgrade project.) Results of the analysis and experiments are presented and analyzed together with the remaining activities planned for the coming months.

Sound pressure level determination around the transformer using coherent and incoherent analytical summation methods

In this paper, coherent and incoherent analytical summation methods from elementary sound sources on the transformer’s tank are presented. They aim to determine a one-third-octave spectrum of sound pressure levels (SPL) in points around the transformer. Each part of the transformer’s surface is treated as a separate plane source so the analytical calculation can be applied to find SPL in the surroundings. Reflections from the ground are also considered by putting an image of the plane sources on the other side of the reflecting plane and adding its contributions to the total pressure in the desired points. Grid-like vibration measurements of vibration velocity on the tank surfaces are used as input parameters. Vibrations and sound pressure levels are measured to validate the method on the 5 MVA transformer experimental object. The SPL around the transformer in short-circuit (SC) and open-circuit (OC) tests is measured in the semi-anechoic chamber to compare it with theoretical results. By analyzing the results, the coherent calculation with reflection provided the most accurate results. In the SC operating condition, the normalized root mean square error (NRMSE) is 17.2%, and in the OC operating condition, it is 10.9%. The novelty of the presented method is that it considers complicated transformer geometry where each surface is calculated as a separate noise source. It calculates noise at a distance from the elementary vibration sources, considering phase and reflection from the hard ground, and provides detailed noise maps that can be used for noise modeling around the substations.

Aeroacoustics of a ducted fan ingesting an adverse pressure gradient boundary layer

The aeroacoustics of a boundary layer ingesting (BLI) ducted fan is investigated experimentally. The study examines a ducted fan immersed in an adverse streamwise pressure gradient turbulent boundary layer developed over a curved wall. Aeroacoustics measurements indicate that the noise from the BLI ducted fan results from a complex interaction among the fan, duct and the incoming boundary layer. The fundamental mechanisms of noise generation are explained using a general source separation strategy. A detailed noise comparison is made at varying fan rotational speeds and across a wide range of axial inflow velocities. In a low thrust regime, the noise is found to be driven by the fan loading, coupled with duct acoustics and the haystacking phenomenon. In a high thrust regime, the contribution from duct acoustics diminishes, and the noise is predominantly driven by the fan loading coupled with the haystacking phenomenon.

A noise audit of human-labeled benchmarks for machine commonsense reasoning

With the advent of large language models, evaluating and benchmarking these systems on important AI problems has taken on newfound importance. Such benchmarking typically involves comparing the predictions of a system against human labels (or a single ‘ground-truth’). However, much recent work in psychology has suggested that most tasks involving significant human judgment can have non-trivial degrees of noise. In his book, Kahneman suggests that noise may be a much more significant component of inaccuracy compared to bias, which has been studied more extensively in the AI community. This article proposes a detailed noise audit of human-labeled benchmarks in machine commonsense reasoning, an important current area of AI research. We conduct noise audits under two important experimental conditions: one in a smaller-scale but higher-quality labeling setting, and another in a larger-scale, more realistic online crowdsourced setting. Using Kahneman’s framework of noise, our results consistently show non-trivial amounts of level, pattern, and system noise, even in the higher-quality setting, with comparable results in the crowdsourced setting. We find that noise can significantly influence the performance estimates that we obtain of commonsense reasoning systems, even if the ‘system’ is a human; in some cases, by almost 10 percent. Labeling noise also affects performance estimates of systems like ChatGPT by more than 4 percent. Our results suggest that the default practice in the AI community of assuming and using a ‘single’ ground-truth, even on problems requiring seemingly straightforward human judgment, may warrant empirical and methodological re-visiting.

Design and performance of an ultrahigh vacuum spectroscopic-imaging scanning tunneling microscope with a hybrid vibration isolation system.

A spectroscopic imaging-scanning tunneling microscope (SI-STM) allows for the atomic scale visualization of the surface electronic and magnetic structure of novel quantum materials with a high energy resolution. To achieve the optimal performance, a low vibration facility is required. Here, we describe the design and performance of an ultrahigh vacuum STM system supported by a hybrid vibration isolation system that consists of a pneumatic passive and a piezoelectric active vibration isolation stage. We present the detailed vibrational noise analysis of the hybrid vibration isolation system, which shows that the vibration level can be suppressed below 10-8 m/sec/√Hz for most frequencies up to 100Hz. Combined with a rigid STM design, vibrational noise can be successfully removed from the tunneling current. We demonstrate the performance of our STM system by taking high resolution spectroscopic maps and topographic images on several quantum materials. Our results establish a new strategy to achieve an effective vibration isolation system for high-resolution STM and other scanning probe microscopies to investigate the nanoscale quantum phenomena.

Acute effects of military aircraft noise on sedative and analgesic drug administrations in psychiatric patients: A case-time series analysis

BackgroundExisting evidence suggests that psychiatric patients are highly noise sensitive, and that noise exposure increases the risk for adverse mental health outcomes, such as psychiatric hospitalizations and even suicide. To investigate acute effects of noise in this vulnerable population, we assessed short-term associations between fighter jet noise and on-demand sedative and analgesic drug administrations in a psychiatric clinic located close to a military airfield in Switzerland. MethodsWe applied a case time series analysis with an hourly time resolution using distributed-lag models. Analysis was adjusted for long-term and seasonal trends, day of week, time of day, time-varying weather conditions and the week of stay. Noise exposure (hourly A-weighted equivalent continuous sound pressure levels (LAeq)) was modelled using detailed flight plans and noise footprints for different fighter jet and route combinations. Outcome data were available from the clinic’s records. OutcomesDuring the study period (06/2016–12/2021), 23,486 flights occurred. 5,968 clinical stays with a median length of 41 days (IQR: 28d, 50d) were recorded. The odds ratio (OR) for medication administration over the lag period of 3 hours after exposure was 1.016 (95 %CI: 1.006, 1.026) per 10 dB LAeq for sedatives and 1.032 (95 %CI: 1.016, 1.048) per 10 dB for analgesics. Effects were larger in multimorbid patients. InterpretationCase time series analysis is a novel method to investigate transient associations in observational data while minimizing risk of bias. Using an objectively recorded outcome measure, our results demonstrate that psychiatric patients are a vulnerable population, in which noise exposure can lead to symptom exacerbations and adverse events.

Compressed Gate Characterization for Quantum Devices with Time-Correlated Noise

As quantum devices make steady progress towards intermediate scale and fault-tolerant quantum computing, it is essential to develop rigorous and efficient measurement protocols that account for known sources of noise. Most existing quantum characterization protocols such as gate-set tomography and randomized benchmarking assume the noise acting on the qubits is Markovian. However, this assumption is often not valid, as for the case of 1/f charge noise or hyperfine nuclear spin noise. Here, we present a general framework for quantum process tomography (QPT) in the presence of time-correlated noise. We further introduce fidelity benchmarks that quantify the relative strength of different sources of Markovian and non-Markovian noise. As an application of our method, we perform a comparative theoretical and experimental analysis of silicon spin qubits. We first develop a detailed noise model that accounts for the dominant sources of noise and validate the model against experimental data. Applying our framework for time-correlated QPT, we find that the number of independent parameters needed to characterize one- and two-qubit gates can be compressed by 10× and 100×, respectively, when compared to the fully generic case. These compressions reduce the amount of tomographic measurements needed in experiment, while also significantly speeding up numerical simulations of noisy quantum circuit dynamics compared to time-dependent Hamiltonian simulation. Using this compressed noise model, we find good agreement between our theoretically predicted process fidelities and two-qubit interleaved randomized benchmarking fidelities of 99.8% measured in recent experiments on silicon spin qubits. More broadly, our formalism can be directly extended to develop efficient and scalable tuning protocols for high-fidelity control of large arrays of quantum devices with non-Markovian noise. Published by the American Physical Society 2024

Noise survey of neonatal intensive care unit at a government tertiary-care centre.

With technological advancement, Neonatal Intensive Care Units (NICU) have become noisier than ever. Studies have shown the detrimental effects of increasing noise in NICU on growing pre-term and sick neonates. The present study aimed to survey the amount of noise in one of the NICU blocks of a government tertiary care centre and explore ways to control it when dealing with these sick babies. A detailed noise survey was carried out, for February 2023, in one of the two blocks of NICU in a government tertiary-care centre. The noise measurements were performed using two "Sound Ear 3" noise meters. The analyses were done in Leq (equivalent continuous sound levels) A-weighted decibels (dBA). The extracted data analysis revealed that the NICU block was exposed to a mean Leq of 67.78 dBA noise with a maximum of 89.0 dBA. There was a significant difference between the values noted in devices at different locations and across different periods. There were certain instances (57 and 42 for two devices) when there were sudden spikes in the noise levels beyond 80 dBA. It was also seen that noise was more than 65 dBA most of the time (72% and 66% for the two devices). The noise survey carried out over one month revealed a considerable amount of noise in the NICU of a government tertiary-care centre. The study also explored ways such as environmental modification, human behavior modification, awareness programs, and neonatal-centered modifications to reduce the noise and lower its detrimental effects on the growth of neonates.

Matched impedance amplifier design for shear-force acoustic near-field microscopy

Efficient detection of the acoustic signal constitutes the most critical aspect in Shear-force Acoustic Near-field Microscopy, for reliably characterize the dynamic response of confined fluids under shear stress. The near-field acoustic emission from the fluid is monitored as the probe gradually approaches to, and subsequently retracts from, the substrate. Herein we report a 7dB improvement in signal-to-noise sensitivity in detecting the acoustic emission from the fluid trapped between a flat sample and the apex of a tapered probe (the latter attached to a quartz tuning fork of 32 kHz resonance frequency). The new design capitalizes on the inherent capacitance of the SANM acoustic sensor (comprising a pile of piezoelectric plates) and a proper matching inductor/capacitance combination to, altogether connected in a tank-circuit fashion, optimize the sensor’s response at 32 kHz. A detailed construction of the circuit amplifier, as well as detailed frequency response bandwidth and noise characterization, is included herein.

Modelling and Evaluation of Noise Dispersion from Wind Turbine Operations

Abstract All over the world, the need for energy is increasing, and the methods of obtaining it are harmful to the environment. Traditional energy resources are rapidly depleting. During the extraction and burning of fossil fuels, many different pollutants enter the environment. One of the renewable forms of energy is wind energy. Wind energy is mainly used to generate electricity in wind farms. Wind turbines are a unique source of noise because they are installed at a high height above the ground, and the noise emitted is fluctuating and manifests itself in a wide frequency range. Noise from wind turbines as low as 32 dB(A) is a strong nervous system irritant for some people, while noise of 40 dB(A) and above causes severe discomfort for many people [1]. Detailed noise modeling was carried out in the considered area, assessing how noise affects individual dwellings, noise in the living environment of residential buildings were modeled. The noise level without background noise sources of the nearest residential environment was determined by modeling at 31.9 dB(A) during the night, while the limit value for the protection of human health according to HN 33:2011 is 45 dB(A).

Optimal Network Design for Microseismic Monitoring in Urban Areas - A Case Study in Munich, Germany

Well-designed monitoring networks are crucial for obtaining precise locations, magnitudes and source parameters, both for natural and induced microearthqakes. The performance of a seismic network depends on many factors, including network geometry, signal-to-noise ratio (SNR) at the seismic station, instrumentation and sampling rate. Therefore, designing a high-quality monitoring network in an urban environment is challenging due to the high level of anthropogenic noise and dense building infrastructure, which can impose geometrical limitations and elevated construction costs for sensor siting. To address these challenges, we apply a numerical optimization approach to design a microseismic surveillance network for induced earthquakes in the metropolitan area of Munich (Germany), where several geothermal plants exploit a deep hydrothermal reservoir. First of all, we develop a detailed noise model for the city of Munich, to capture the heterogeneous noise conditions. Then, we calculate the expected location precision for a randomly chosen network geometry from the body-wave amplitudes and travel times of a synthetic earthquake catalog considering the modeled local noise level at each network station. In the next step, to find the optimum network configuration, we use a simulated annealing approach in order to minimize the error ellipsoid volume of the linearized earthquake location problem. The results indicate that a surface station network cannot reach the required location precision (0.5 km in epicentre and 2 km in source depth) and detection capability (magnitude of completeness Mc = 1.0) due to the city´s high seismic noise level. In order to reach this goal, borehole stations need to be added to increase the SNR of the microearthquake recordings, the accuracy of their body-wave arrival times and source parameters. The findings help to better quantify the seismic monitoring requirements for a save operation of deep geothermal projects in urban areas.

A vital signsignal noise suppression method for wearable piezoelectric devices.

This paper tackles the problem of noise suppression during vital signsignal monitoring. Physiological signal monitoring is a significant and promising medical monitoring method, and wearable medical monitoring devices based on piezoelectric polymer sensors are a trending way for their advantages of being flexible in the shape, portable to use, and comfortable to wear. However, this raises the question that the measured signal contains much more noise components. To avoid the following shortcoming of low signal to noise ratio (SNR), a noise suppression method based on improved wavelet threshold and empirical mode decomposition combined with singular value decomposition (SVD) screening the intrinsic mode function (IMF) components is proposed. A wavelet transform is first used under the combination of hard and soft thresholds to focus the target range in the low-frequency region where the energy of the physiological signal is concentrated. Then, a complete ensemble empirical mode decomposition is used to decompose the signal effectively, which can resist the influence of random noises. Meanwhile, a SVD decomposition procedure was used to filter out the lower correlated IMF components to retain the validity of the original signal. We verified the effectiveness of the proposed method through simulated and measured experiments as well as the advantages and disadvantages of the algorithm compared with other physiological signal denoising algorithms through SNR filtering results, power spectrum distribution, and other perspectives. The results proved that the proposed method could effectively remove more detailed noise and improve the SNR of the signal efficiently, which is more conducive to the demand for auxiliary medical diagnosis in the future.

Passive state preparation continuous variable quantum key distribution in a satellite-mediated link

Passive state preparation (PSP) continuous variable quantum key distribution (CVQKD) drops out optical amplitude and phase modulators, making this scheme suitable for application in space-confined situations. In this paper, we propose a satellite-mediated PSP-CVQKD scheme. To improve the performance of the scheme further, we introduce a phase-insensitive amplifier (PIA) at the receiver side. Based on the detailed noise model and channel parameter estimation analysis, we perform numerical simulations of the proposed scheme while the finite-size effect is considered. Simulation results show that the satellite-mediated PSP-CVQKD is feasible in both downlink and uplink cases based on typical system parameters. The performance can be improved at a relatively low satellite altitude when the PIA is used. Our analysis demonstrates that the proposed scheme may be a potentially cost-effective solution for future chip-scale CVQKD over satellite-mediated links.

Spatiotemporal evaluation of Rayleigh surface wave estimated from roadside dark fiber DAS array and traffic noise

Seismic imaging and monitoring of the near-surface structure are crucial for the sustainable development of urban areas. However, standard seismic surveys based on cabled or autonomous geophone arrays are expensive and hard to adapt to noisy metropolitan environments. Distributed acoustic sensing (DAS) with pre-existing telecom fiber optic cables, together with seismic ambient noise interferometry, have the potential to fulfill this gap. However, a detailed noise wavefield characterization is needed before retrievingcoherent waves from chaotic noise sources. We analyze local seismic ambient noise by tracking five-month changes in signal-to-noise ratio (SNR) of Rayleigh surface wave estimated from traffic noise recorded by DAS along the straight university campus busy road. We apply the seismic interferometry method to the 800 m long part of the Penn State Fiber-Optic For Environment Sensing (FORESEE) array. We evaluate the 160 virtual shot gathers (VSGs) by determining the SNR using the slant-stack technique. We observe strong SNR variations in time and space. We notice higher SNR for virtual source points close to road obstacles. The spatial noise distribution confirms that noise energy focuses mainly on bumps and utility holes. We also see the destructive impact of precipitation, pedestrian traffic, and traffic along main intersections on VSGs. A similar processing workflow can be applied to various straight roadside fiber optic arrays in metropolitan areas.

Accessing the full capabilities of filter functions: Tool for detailed noise and quantum control susceptibility analysis

Accessing the full capabilities of filter functions: Tool for detailed noise and quantum control susceptibility analysis

Noise analysis of the atomic superheterodyne receiver based on flat-top laser beams.

Since its theoretical sensitivity is limited by quantum noise, radio wave sensing based on Rydberg atoms has the potential to replace its traditional counterparts with higher sensitivity and has developed rapidly in recent years. However, as the most sensitive atomic radio wave sensor, the atomic superheterodyne receiver lacks a detailed noise analysis to pave its way to achieve theoretical sensitivity. In this work, we quantitatively study the noise power spectrum of the atomic receiver versus the number of atoms, where the number of atoms is precisely controlled by changing the diameters of flat-top excitation laser beams. The results show that under the experimental conditions that the diameters of excitation beams are less than or equal to 2 mm and the read-out frequency is larger than 70 kHz, the sensitivity of the atomic receiver is limited only by the quantum noise and, in the other conditions, limited by classical noise. However, the experimental quantum-projection-noise-limited sensitivity this atomic receiver reaches is far from the theoretical sensitivity. This is because all atoms involved in light-atom interaction will contribute to noise, but only a fraction of them participating in the radio wave transition can provide valuable signals. At the same time, the calculation of the theoretical sensitivity considers both the noise and signal are contributed by the same amount of atoms. This work is essential in making the sensitivity of the atomic receiver reach its ultimate limit and is significant in quantum precision measurement.