Narrow-band Noise Research Articles

Dynamic properties of a one-dimensional charge density wave compound in the presence of uncondensed-carriers: Insights from numerical experiences

In the present Letter, a numerical study of the dynamic properties of one-dimensional (1D) incommensurate charge density wave (CDW) compound in the presence of free carriers (not affected by the Peierls transition) is carried out. The results obtained showed that the CDW sliding state is very sensitive to this local effect. The CDW depinning threshold field, excess current normalized and amplitude of Narrow-Band-Noise (NBN) are affected by these single particle’s excitations. This latter can be viewed as a screening effect of the applied electrical field by free carriers which relax in order to reduce the CDW polarization and generate a homogeneous system response.

Human Auditory Detection and Discrimination Measured with the Pupil Dilation Response

In the standard Hughson-Westlake hearing tests (Carhart and Jerger 1959), patient responses like a button press, raised hand, or verbal response are used to assess detection of brief test signals such as tones of varying pitch and level. Because of its reliance on voluntary responses, Hughson-Westlake audiometry is not suitable for patients who cannot follow instructions reliably, such as pre-lingual infants (Northern and Downs 2002). As an alternative approach, we explored the use of the pupillary dilation response (PDR), a short-latency component of the orienting response evoked by novel stimuli, as an indicator of sound detection. The pupils of 31 adult participants (median age 24 years) were monitored with an infrared video camera during a standard hearing test in which they indicated by button press whether or not they heard narrowband noises centered at 1, 2, 4, and 8 kHz. Tests were conducted in a quiet, carpeted office. Pupil size was summed over the first 1750 ms after stimulus delivery, excluding later dilations linked to expenditure of cognitive effort (Kahneman and Beatty 1966; Kahneman et al. 1969). The PDR yielded thresholds comparable to the standard test at all center frequencies tested, suggesting that the PDR is as sensitive as traditional methods of assessing detection. We also tested the effects of repeating a stimulus on the habituation of the PDR. Results showed that habituation can be minimized by operating at near-threshold stimulus levels. At sound levels well above threshold, the PDR habituated but could be recovered by changing the frequency or sound level, suggesting that the PDR can also be used to test stimulus discrimination. Given these features, the PDR may be useful as an audiometric tool or as a means of assessing auditory discrimination in those who cannot produce a reliable voluntary response.

The Development and Applications of the Helicopter-borne Transient Electromagnetic System CAS-HTEM

Over the past decade, helicopter-borne transient electromagnetic (HTEM) systems have been rapidly developed. A new HTEM prototype (referred to as a CAS-HTEM) has been developed by the Chinese Academy of Sciences. In terms of hardware, the CAS-HTEM system uses an inflatable structure to carry the transmitting loop, which significantly reduces the weight of the system and makes it easier to transport. A dual gain receiver was innovated to extend the dynamic range of the system. In addition, an observation circuit for transmitting voltage waveform is introduced, so that the derivative waveform of transmitting current with higher SNR could be calculated. In terms of data processing, more reliable early time data could be obtained by band-limited effect removal; a weighted stacking algorithm is introduced to reduce the narrow band noise more effectively and increase the sensitivity of data to the anomaly location; a method based on τ-domain transform is used for late time signal processing. The results of the field test which was carried out in Inner Mongolia were found to be consistent with the drill data, which effectively verified the performance of this HTEM prototype.

Method of estimation of hidden correlation of narrowband noise signals

The concept of hidden correlation of noise signals is introduced. The existence of a hidden correlation between narrowband noise signals isolated simultaneously from broadband band-limited noise is theoretically proved. A method for estimating the latent correlation of narrowband noise signals has been developed and experimentally investigated. As a result of the experiment, where a time frag ent of band-limited noise, the basis of which is shot noise, is used as the studied signal, it is established: when applying the Pearson criterion, there is practically no correlation between the signal at the Central frequency and the sum of signals at mirror frequencies; when applying the proposed method for the analysis of the same signals, a strong hidden correlation is found. The proposed method is useful for researchers, engineers and metrologists engaged in digital signal processing, as well as developers of measuring instruments using a new technology for isolating a useful signal from noise – the method of mirror noise images.

Temporal weights in loudness: Investigation of the effects of background noise and sound level.

Previous research has consistently shown that for sounds varying in intensity over time, the beginning of the sound is of higher importance for the perception of loudness than later parts (primacy effect). However, in all previous studies, the target sounds were presented in quiet, and at a fixed average sound level. In the present study, temporal loudness weights for a time-varying narrowband noise were investigated in the presence of a continuous bandpass-filtered background noise and the average sound levels of the target stimuli were varied across a range of 60 dB. Pronounced primacy effects were observed in all conditions and there were no significant differences between the temporal weights observed in the conditions in quiet and in background noise. Within the conditions in background noise, there was a significant effect of the sound level on the pattern of weights, which was mainly caused by a slight trend for increased weights at the end of the sounds (“recency effect”) in the condition with lower average level. No such effect was observed for the in-quiet conditions. Taken together, the observed primacy effect is largely independent of masking as well as of sound level. Compatible with this conclusion, the observed primacy effects in quiet and in background noise can be well described by an exponential decay function using parameters based on previous studies. Simulations using a model for the partial loudness of time-varying sounds in background noise showed that the model does not predict the observed temporal loudness weights.

Detection of weak multi-target with adjacent frequency based on chaotic system

As a promising technology in signal detection, the chaotic detection system can significantly improve the accuracy of weak signal detection in strong background noise. It benefits from its characteristics of the sensitivity to the initial condition and the immunity to the Additive White Gaussian Noise. However, the fundamental challenges of the existing chaotic detection system are the sensitivity to narrow-band noise and the influences of multi-target detection with adjacent frequency, which bring great difficulties in the real application. To address these problems, in this article, we focus on the weak multi-target detection with adjacent frequency under the narrow-band noise, and a novel chaotic detection system that integrates the detection algorithm based on period-chaos duration ratio is proposed. In order to enhance the robustness to narrow-band noise, the Melnikov method is used to analyze the Duffing difference system. To realize the detection of weak multi-target with adjacent frequency, we proposed the detection system using the rule named general critical state. Furthermore, simulation results corroborate that the proposed system based on period-chaos duration ratio can achieve satisfactory performance in terms of the weak multi-target detection under narrow-band noise, and it is well investigated by extensive simulation for testing its effectiveness.

The Design and Implementation of Notch Filter Based on Least Mean Square

Data acquisition and analysis system often encounters interference of single frequency or narrowband signal in work. For example, in power frequency environment, 50Hz interference signal often affects the normal operation of the system and affects the effect of data acquisition and analysis. For narrowband or single frequency noise, the best denoising method is notch filter. This paper describes the design of notch filter based on least mean square (LMS) algorithm and its implementation based on single chip computer platform. The simulation and experimental results show that this method achieves good results in filtering effect and system computing speed.

Suppression of aerodynamic noise using dual-jet air curtains combined with perforated fairings

The dual-jet air curtain is a novel technology that, acting as a fluidic spoiler, can not only reduce aerodynamic noise but also, compared with a single-jet air curtain, can be designed to have low self noise. To achieve further progress, this paper proposes a combined use of the dual-jet air curtain with a perforated fairing. The concept was evaluated with wind tunnel experiments using tandem rods acting as an aerodynamic bluff body noise source creating suitably high amplitude narrowband and broadband noise output. In the experiment, two configurations of the combined use were tested, i.e. the fairing was located either upstream or downstream to the rods. It was found that the two technologies complement each other with the dual-jet air curtain reducing the high frequency turbulent shear layer noise emitted from the edge of the perforated fairing, whilst the perforated fairing serves to reduce the velocity of recirculating flow in the lee of the aircurtain, thus reducing this potential aerodynamic noise source.

Temporal loudness weights in background noise: Data and models

Previous studies consistently showed that human listeners primarily consider the beginning of a time-varying sound when judging its overall loudness, and place less weight on subsequent temporal portions. However, all experiments studying this primacy effect in temporal loudness weights presented the target sound in quiet. Here, we compared temporal weights when the target sound was either presented in quiet or in a continuous background noise, and for a variation in the level of the target sound across a range of 60 dB. The target sound was a time-varying narrowband noise, the background noise was a continuous bandpass-filtered noise. In all conditions, we observed the expected primacy effect, well described by an exponential decay function using parameters based on previous studies. The patterns of temporal weights were very similar in conditions with and without background noise, and largely independent of the variation in target level. Simulations using a dynamical model for the partial loudness of time-varying sounds in background noise showed that the model does not predict the observed temporal loudness weights. Strongly depending on the loudness statistic extracted from the loudness model, the predicted loudness weights were either uniform, or showed an inverse U-shaped pattern with higher weights predicted for temporal portions in the middle of the sound compared to temporal portions near onset or offset.Previous studies consistently showed that human listeners primarily consider the beginning of a time-varying sound when judging its overall loudness, and place less weight on subsequent temporal portions. However, all experiments studying this primacy effect in temporal loudness weights presented the target sound in quiet. Here, we compared temporal weights when the target sound was either presented in quiet or in a continuous background noise, and for a variation in the level of the target sound across a range of 60 dB. The target sound was a time-varying narrowband noise, the background noise was a continuous bandpass-filtered noise. In all conditions, we observed the expected primacy effect, well described by an exponential decay function using parameters based on previous studies. The patterns of temporal weights were very similar in conditions with and without background noise, and largely independent of the variation in target level. Simulations using a dynamical model for the partial loudness of ti...

Non-linear noise from a ship propeller in open sea condition

In the present paper, we study the hydrodynamic noise generated by a ship propeller in open sea conditions. We use Large Eddy Simulation for the hydrodynamic field whereas the acoustic field is reconstructed by applying the advective form of the Ffowcs-Williams and Hawkings equation. A dynamic Lagrangian model is adopted for the closure of the subgrid-scale stresses and a wall-layer model allows to skip the resolution of the viscous sub-layer. The acoustic equation is formulated in the integral form and solved through direct integration of the volume terms. The propeller herein considered is a benchmark case, whose fluid dynamic data are available in the literature. A grid of about 3 ×106 cells is able to reproduce accurately both integral quantities like thrust and torque over the propeller, and turbulence propagating downstream in the wake.Different noise generation mechanisms are investigated separately. The linear terms give rise to a narrow-band noise spectrum, with a mean peak at the blade frequency and other peaks at frequencies multiple of the rotational one. The non-linear quadrupole term reveals a broad band noise spectrum; the shaft vortex provides the largest contribution to the non-linear part of the noise propagated in the far field.

Neural signatures of temporal regularity processing in sounds differ between younger and older adults

Sensitivity to temporal regularity (e.g., recurring modulation in amplitude) is crucial for speech perception. Degradation of the auditory periphery due to aging and hearing loss may lead to increased responsiveness to sound in the auditory cortex, with potential consequences for the processing of temporal regularities. We used electroencephalography recorded from younger (19–33 years) and older adults (55–76 years) to investigate whether younger and older listeners differ in responsiveness to sound and sensitivity to amplitude modulation in sounds. Aging was associated with reduced adaptation in the auditory cortex, suggesting an age-related increase in responsiveness. Furthermore, neural synchronization in the auditory cortex to 4-Hz amplitude-modulated narrow-band noises was enhanced in ∼30% of older individuals. Despite enhanced responsiveness and synchronization in the auditory cortex, sustained neural activity (likely involving auditory and higher-order regions) in response to amplitude modulation was absent in older people. Aging appears to be associated with over-responsiveness to amplitude modulation in the auditory cortex, but with diminished regularity sensitivity in higher-order areas.

Slow steady flow of a skyrmion lattice in a confined geometry probed by narrow-band resistance noise

Using resistance fluctuation spectroscopy, we observe current-induced narrow-band noise (NBN) in the magnetic skyrmion-lattice phase of micrometer-sized MnSi. The NBN appears only when electric-current density exceeds a threshold value, indicating that the current-driven motion of the skyrmion lattice triggers the NBN. The observed NBN frequency is 10-10$^4$ Hz at $\sim$10$^{9}$ A/m$^{2}$, implying a skyrmion steady flow velocity of 1-100 $\mu$m/s, 3-5 orders of magnitude slower than previously reported. The temperature evolution of the NBN frequency suggests that the steady flow entails thermally activated processes, which are most likely due to skyrmion creation and annihilation at the sample edges. This scenario is qualitatively supported by our numerical simulations considering boundary effects, which reveals that the edges limit the steady flow of skyrmions, especially at low temperatures. We discuss a mechanism that dramatically slows the skyrmion steady flow in a microfabricated specimen.

The barn owls' Minimum Audible Angle.

Interaural time differences (ITD) and interaural level differences (ILD) are physical cues that enable the auditory system to pinpoint the position of a sound source in space. This ability is crucial for animal communication and predator-prey interactions. The barn owl has evolved an exceptional sense of hearing and shows abilities of sound localisation that outperform most other species. So far, behavioural studies in the barn owl often used reflexive responses to investigate aspects of sound localisation. Furthermore, they predominately probed the higher frequencies of the owl’s hearing range (> 3 kHz). In the present study we used a Go/NoGo paradigm to measure the barn owl’s behavioural sound localisation acuity (expressed as the Minimum Audible Angle, MAA) as a function of stimulus type (narrow-band noise centred at 500, 1000, 2000, 4000 and 8000 Hz, and broad-band noise) and sound source position. We found significant effects of both stimulus type and sound source position on the barn owls’ MAA. The MAA improved with increasing stimulus frequency, from 14° at 500 Hz to 6° at 8000 Hz. The smallest MAA of 4° was found for broadband noise stimuli. Comparing different sound source positions revealed smaller MAAs for frontal compared to lateral stimulus presentation, irrespective of stimulus type. These results are consistent with both the known variations in physical ITDs and variation in the width of neural ITD tuning curves with azimuth and frequency. Physical and neural characteristics combine to result in better spatial acuity for frontal compared to lateral sounds and reduced localisation acuity at lower frequencies.

Extraction of Partial Discharge Pulses from the Complex Noisy Signals of Power Cables Based on CEEMDAN and Wavelet Packet

While both periodic narrowband noise and white noise are significant sources of interference in the detection and localization of partial discharge (PD) signals in power cables, existing research has focused nearly exclusively on white noise suppression. This paper addresses this issue by proposing a new signal extraction method for effectively detecting random PD signals in power cables subject to complex noise environments involving both white noise and periodic narrowband noise. Firstly, the power cable signal was decomposed using complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN), and the periodic narrowband noise and frequency aliasing in the obtained signal components were suppressed using singular value decomposition. Then, signal components contributing significantly to the PD signal were determined according to the cross-correlation coefficient between each component and the original PD signal, and the PD signal was reconstructed solely from the obtained significant components. Finally, the wavelet packet threshold method was used to filter out residual white noise in the reconstructed PD signal. The performance of the proposed algorithm was demonstrated by its application to synthesized PD signals with complex noise environments composed of both Gaussian white noise and periodic narrowband noise. In addition, the time-varying kurtosis method was demonstrated to accurately determine the PD signal arrival time when applied to PD signals extracted by the proposed method from synthesized signals in complex noise environments with signal-to-noise ratio (SNR) values as low as −6 dB. When the SNR was reduced to −23 dB, the arrival time error of the PD signal was only one sampling point.

Choice of test stimulus matters for pitch matching performance: Comparison between pure tone and narrow band noise

Chronic tinnitus, a symptom of high prevalence, is a persistent hearing sensation in the absence of an external sound source. Recent electrophysiological studies indicate that tinnitus generation is to a high degree the result of maladaptive plasticity in the central auditory pathway. The pitch of the tinnitus sensation can be assessed by performing a pitch matching procedure. In the most frequent “tonal tinnitus” type pure tones are used as test stimuli. However, in the case of tonal tinnitus not a single malfunctioning neuron, but rather a population of neighbouring neurons is involved in the generation process of tinnitus and patients typically perceive their tinnitus as a sound having a prominent centre frequency with some spectral extent. Thus, the question arises, why not to use narrow band noise (NBN) instead of pure tones as test stimuli in pitch matching procedures? To investigate this, we first evaluated the pitch matching performance of healthy subjects. In a recursive two alternative choice testing, driven by a computer based automated procedure, the subjects were asked to match the pitch of two sounds. In a crosswise design, NBNs and pure tones were used both as target and as test stimuli. We were able to show that across all four possible combinations the pitch matching performance was least favourable when a sinusoidal sound had to be matched to an NBN target. Even though matching two sinusoidal sounds results in the lowest error, considering that the tinnitus percept typically includes some spectral extent, an NBN should be preferably used as a test stimulus against a pure tone.

Comodulation detection difference and binaural unmasking.

The present study investigated the combined effect of binaural cues and comodulation for a narrowband target noise masked by a narrowband noise. The threshold difference between a diotic condition (same stimuli in both ears) and a dichotic condition (target interaural phase difference of π and diotic masker) decreased with spectral distance between masker and target, irrespective of across-frequency envelope correlation. The threshold difference between a condition with comodulated target and masker and a corresponding uncorrelated condition, i.e., the comodulation detection difference, did not depend on target frequency and interaural correlation, indicating that these two stimulus properties are processed independently.

Variational mode decomposition linked wavelet method for EMAT denoise with large lift-off effect

Electromagnetic acoustic transducer (EMAT) is an emerging non-destructive testing technique which is widely used in the industry. EMAT has advantages of a non-coupling agent with the capability of big lift-off detection. However, EMAT has an issue of low efficiency in conversion and it is susceptible to noise. This paper proposes a modified variational mode decomposition (VMD) linked wavelet method for EMAT denoising. It enables to suppress both high-frequency narrowband noise and normal noise in EMAT signals with a large lift-off detection condition. In particular, a new ultrasonic echo signal model with a large lift-off influence is proposed for interpretation of denoising mechanism. To investigate the efficacy and the robustness of the proposed method, experimental studies have been carried out for different test samples. A comparative analysis has been undertaken to confirm that the proposed method not only removes the noise but also preserves the information of defect. The Matlab demo code can be linked: http://faculty.uestc.edu.cn/gaobin/zh_CN/lwcg/153392/list/index.htm.

Behavioral evaluation of auditory function abnormalities in adult rats with normal hearing thresholds that were exposed to noise during early development

Noise-exposed rat pups provide a model of early deprivation of sensory input to the central auditory system, allowing the study of developmental neuroplasticity. Our previous results have demonstrated that a brief exposure of rats to broadband noise (125 dB SPL 8 min, 14th postnatal day) at the onset of hearing resulted in an altered intensity perception and frequency discrimination in adulthood despite normal hearing thresholds. In this study, we assessed the gap-detection ability and possible presence of tinnitus- and hyperacusis-like behavior in adult rats after the same neonatal acoustic trauma, using measurements of the acoustic startle response (ASR) in quiet and noisy environments and its prepulse inhibition by gaps in noise (gap-PPI). A significant deficit in the ability to detect gap was observed in the exposed rats when 55 dB SPL broadband noise was used as background. An increase of noise intensity to 65–75 dB SPL led to strengthening of the gap-PPI in exposed animals, which approached the gap-PPI values of control animals at these levels. Behavioral signs of tinnitus (gap detection deficits in 10 kHz narrow band noise) were found in 25% of exposed rats. An increased sensitivity to continuous noise was manifested in all exposed rats by suppression of the ASR at significantly lower background noise levels than in the controls. This effect was particularly pronounced in rats with tinnitus-like behavior. Our results indicate that neonatal acoustic trauma, producing only a transient threshold shift, may produce permanent abnormalities in suprathreshold auditory functions and the development of tinnitus and hyperacusis-like behavior.

Baseline Functional Connectivity Features of Neural Network Nodes Can Predict Improvement After Sound Therapy Through Adjusted Narrow Band Noise in Tinnitus Patients.

Previous resting-state functional magnetic resonance imaging (fMRI) studies have shown neural connectivity alterations after the treatment of tinnitus. We aim to study the value of the baseline functional connectivity features of neural network nodes to predict outcomes of sound therapy through adjusted narrow band noise. The fMRI data of 27 untreated tinnitus patients and 27 matched healthy controls were analyzed. We calculated the graph-theoretical metric degree centrality (DC) to characterize the functional connectivity of the neural network nodes. Therapeutic outcomes are determined by the changes in the Tinnitus Handicap Inventory (THI) score after a 12-week intervention. The connectivity of 10 brain nodes in tinnitus patients was significantly increased at baseline. The functional connectivity of right insula, inferior parietal lobule (IPL), bilateral thalami, and left middle temporal gyrus was significantly modified with the sound therapy, and such changes correlated with THI changes in tinnitus patients. Receiver operating characteristic curve analyses revealed that the measurements from the five brain regions were effective at classifying improvement after therapy. After age, gender, and education correction, the adjusted area under the curve (AUC) values for the bilateral thalami were the highest (left, 0.745; right, 0.708). Our study further supported the involvement of the fronto-parietal-cingulate network in tinnitus and found that the connectivity of the thalamus at baseline is an object neuroimaging-based indicator to predict clinical outcome of sound therapy through adjusted narrow band noise.

Application of Wireless Contralateral Routing of Signal Technology in Unilateral Cochlear Implant Users with Bilateral Profound Hearing Loss.

The aim of the study was to determine if contralateral routing of signal (CROS) technology results in improved hearing outcomes in unilateral cochlear implant (CI) patients and provides similar gains in speech perception in noise to traditional monaural listeners (MLs). The study is a prospective, within-subject repeated-measures experiment. Adult, English-speaking patients with bilateral severe-profound sensorineural hearing loss using an Advanced Bionics CI (n = 12) in one ear were enrolled for the study. Hearing performance in the monaural listening condition (CI only) was compared with the CROS-aided (unilateral CI + CROS) condition. Participants were tested for speech-in-noise performance using the Bamford-Kowal-Bench Speech-in-Noise™ test materials in the speech front/noise front (0 degrees/0 degrees azimuth), speech front/noise back (0 degrees/180 degrees azimuth), speech deaf ear/noise monaural ear (90 degrees/270 degrees azimuth), and speech monaural ear/noise deaf ear (90 degrees/270 degrees azimuth) configurations. Localization error was assessed using three custom stimuli consisting of 1/3 octave narrowband noises centered at 500 and 4000 Hz and a broadband speech stimulus. Localization stimuli were presented at random in the front hemifield by 19 speakers spatially separated by 10 degrees. Outcomes were compared with a previously described group of traditional MLs in the CROS-aided condition (normal hearing ear + CROS). All participants were tested acutely with no adaptation to the CROS device. Statistical analyses were performed using Wilcoxon signed rank tests for nonparametric data and paired sample. Statistical significance was set to p < 0.00625 after Bonferroni adjustment for eight tests. Significant benefit was observed from unaided to the CI + CROS-aided condition for listening in noise across most listening conditions with the greatest benefit observed in the speech deaf ear/noise monaural ear (90 degrees/270 degrees azimuth) condition (p < 0.0005). When compared with traditional MLs, no significant difference in decibel gain from the unaided to CROS-aided conditions was observed between participant groups. There was no improvement in localization ability in the CROS-aided condition for either participant group and no significant difference in performance between traditional MLs and unilateral CI listeners. These findings support that unilateral CI users are capable of achieving similar gains in speech perception to that of traditional MLs with wireless CROS. These results indicate that the use of wireless CROS stimulation in unilateral CI recipients provides increased benefit and an additional rehabilitative option for this population when bilateral implantation is not possible. The results suggest that noninvasive CROS solutions can successfully rehabilitate certain monaural listening deficits, provide improved hearing outcomes, and expand the reach of treatment in this population.