Hz Frequency Range Research Articles

Influence of sigmoid plate and dura mater on vascular wall displacement, vibroacoustic/hydroacoustic sources characteristics, and frequency-loudness assessments of venous pulsatile tinnitus: A coupled-computational fluid dynamics study combining transcanal recording investigation

Investigations of pulsatile tinnitus (PT) caused by sigmoid sinus wall anomalies (SSWAs) using computational fluid dynamics (CFD) have recently increased in prevalence. However, accurate modeling of anatomical structures regarding sigmoid plate dehiscence and acoustic sources of PT remains lacking. This study incorporates coupled CFD techniques, micro-computed tomography, and scanning electron microscope to reveal the vibroacoustic and hydroacoustic sources and displacement characteristics of the transverse-sigmoid sinus system. Furthermore, the in vivo transcanal-recording technique combined with ipsilateral internal jugular vein compression was implemented to cross-reference the captured acoustic profile of PT with the calculated results. In this study, the transient state coupled CFD technique was used to calculate the vibroacoustic and hydroacoustic sources. The dehiscent sigmoid plate and periosteal dura mater were then reconstructed. The displacement characteristics and acoustic results were analyzed. The displacement of the vascular wall underneath the dehiscent area was 9.6 times larger than that of the sigmoid plate and 3,617 times smaller than that of the vascular wall without the overlying osseous structures. The peak amplitude of flow-induced vibroacoustic noise was 119.3dB at 20.2Hz measured at the transverse sinus. Within the observed 20-1,000Hz frequency range, the largest peak amplitude of hydroacoustic noise was 80.0dB at 20.2Hz located at the jugular bulb region. The simulated results conformed with the in vivo acoustic profile which the major frequency of PT falls within 1,000Hz. In conclusion, 1) the sigmoid plate and dura mater greatly impact vascular wall displacement, which should not be overlooked in CFD simulations. 2) By incorporating the transcanal recording technique with IJV compression test, the primary frequency of PT was found fluctuating below 1,000Hz, which matches the frequency component simulated by the current CFD technique; amplitude-wise, however, the peak amplitude of in vivo pulse-synchronous somatosound measures approximately 10dB, which is comparatively lesser than the CFD results and the subjectively perceived loudness of PT. Thus, the transmission pathway, intramastoid acoustic impedance/amplification effect, and the perceptive threshold of PT require further investigations to minimize the incidence of surgical failure.

Identification of spatial patterns with maximum association between power of resting state neural oscillations and trait anxiety

Anxiety affects approximately 5–10% of the adult population worldwide, placing a large burden on the health systems. Despite its omnipresence and impact on mental and physical health, most of the individuals affected by anxiety do not receive appropriate treatment. Current research in the field of psychiatry emphasizes the need to identify and validate biological markers relevant to this condition. Neurophysiological preclinical studies are a prominent approach to determine brain rhythms that can be reliable markers of key features of anxiety. However, while neuroimaging research consistently implicated prefrontal cortex and subcortical structures, such as amygdala and hippocampus, in anxiety, there is still a lack of consensus on the underlying neurophysiological processes contributing to this condition. Methods allowing non-invasive recording and assessment of cortical processing may provide an opportunity to help identify anxiety signatures that could be used as intervention targets. In this study, we apply Source-Power Comodulation (SPoC) to electroencephalography (EEG) recordings in a sample of participants with different levels of trait anxiety. SPoC was developed to find spatial filters and patterns whose power comodulates with an external variable in individual participants. The obtained patterns can be interpreted neurophysiologically. Here, we extend the use of SPoC to a multi-subject setting and test its validity using simulated data with a realistic head model. Next, we apply our SPoC framework to resting state EEG of 43 human participants for whom trait anxiety scores were available. SPoC inter-subject analysis of narrow frequency band data reveals neurophysiologically meaningful spatial patterns in the theta band (4–7 Hz) that are negatively correlated with anxiety. The outcome is specific to the theta band and not observed in the alpha (8–12 Hz) or beta (13–30 Hz) frequency range. The theta-band spatial pattern is primarily localised to the superior frontal gyrus. We discuss the relevance of our spatial pattern results for the search of biomarkers for anxiety and their application in neurofeedback studies.

Validation of a ride comfort simulation strategy on an electric Stewart Platform for real road driving applications

In this paper, the validation of the comfort simulation strategy on an electric Stewart Platform under road driving scenarios is explained. First, an introduction to the vibroacoustic comfort theory in passenger cars is presented. Second, the Stewart Platform used for the validation process is explained. Third, the methodology conducted for the validation of a hexapod for ride comfort applications is detailed. Finally, the Stewart Platform has been validated under real world road driving scenarios for the 6 degrees-of-freedom by means of the Vibration Dose Value. The final goal of the validation strategy of the electric Stewart Platform is to perform ride and comfort studies in a driving simulator for the 1–10 Hz frequency range.

An automated pipeline for scattered light noise characterization

Scattered light noise (or scattering) affects the sensitivity of gravitational wave detectors in their detection frequency band. The mitigation of such nonlinear and nonstationary noise can be carried out experimentally and employing data analysis techniques, e.g., applying adaptive algorithms to the data affected by noise. We present gwas , a fully automated pipeline based on the time-varying filter empirical mode decomposition (tvf-EMD) algorithm, to identify, characterize, and monitor objects inducing scattering to the gravitational wave detector’s output. The tvf-EMD algorithm is suitable for decomposing signals with time-dependent frequency, such as scattering. The pipeline application to LIGO Livingston data shows that most of the scattering noise present in the third observation run was due to the penultimate mass at the end of the X-arm of the detector (EXPUM), whose motion is excited in the 0.1 Hz to 0.3 Hz frequency range (so-called microseismic band). Furthermore, we show that the pipeline can perform daily analyses, and we test it on six days of LIGO Livingston data. These analyses allowed monitoring of the onset and time evolution of scattering due to the EXPUM in connection with the variability of microseismic band noise measured at the detector site.

Default mode network mediates low-frequency fluctuations in brain activity and behavior during sustained attention.

The low-frequency (<0.1Hz) fluctuation in sustained attention attracts enormous interest in cognitive neuroscience and clinical research since it always leads to cognitive and behavioral lapses. What is the source of the spontaneous fluctuation in sustained attention in neural activity, and how does the neural fluctuation relate to behavioral fluctuation? Here, we address these questions by collecting and analyzing two independent fMRI and behavior datasets. We show that the neural (fMRI) fluctuation in a key brain network, the default-mode network (DMN), mediate behavioral (reaction time) fluctuation during sustained attention. DMN shows the increased amplitude of fluctuation, which correlates with the behavioral fluctuation in a similar frequency range (0.01-0.1Hz) but not in the lower (<0.01 Hz) or higher (>0.1Hz) frequency range. This was observed during both auditory and visual sustained attention and was replicable across independent datasets. These results provide a novel insight into the neural source of attention-fluctuation and extend the former concept that DMN was deactivated in cognitive tasks. More generally, our findings highlight the temporal dynamic of the brain-behavior relationship.

Enhancement of the Dielectric Properties of Polyvinyl Alcohol by Adding TiO2Nanoparticles

High dielectric constant nanocomposite polymer films based polyvinyl alcohol (PVA) with different weight ratios of nanoparticles (NPs) TiO2(1.0, 2.5, 5.0, and 10) are prepared by the casting method. The structure of TiO2NPs is studied using TEM and XRD spectra, where the FTIR spectra show a strong interaction between PVA and TiO2NPs. The addition of TiO2NPs to the composites improves their mechanical properties. The dielectric parameters and AC conductivity are explored in the 10 Hz to 107 Hz frequency range at different temperatures. PVA composite films filled with 5.0 wt% TiO2NPs exhibit the highest dielectric constant (ε′) reaching up to 26 at 25 °C and 100 Hz. The origins of the enhanced dielectric properties are investigated using theoretical predictions of the effectiveε′of composites. The activation energy of a dielectric relaxation process is computed. As the temperature rises, the relaxation time lengthens slightly. A conduction mechanism is described based on thermally activated electron hops at the Fermi edge.

Inkjet 3D Printed MEMS Electromagnetic Multi-Frequency Energy Harvester

Multi-frequency operation is an interesting and desired feature of electromagnetic energy harvesters. This work presents results of investigations on an inkjet 3D-printed miniature multi-frequency electromagnetic energy harvester. Vibrating microstructures utilizing springs with constant thickness (300 μm) and widths from 220 to 500 μm were designed, fabricated, and characterized as parts of the miniature energy harvester. Resonant frequencies of the microstructures were measured, and electrical parameters of the harvester were determined. The harvesters operated in the 85–185 Hz frequency range with 32 µW maximal output power. Thanks to flexibility in designing and fabrication by 3D printing, it was possible to develop an energy harvester with at least two operating frequencies within a single harvester structure in many possible two-frequency configurations.

Visual biospeckle analysis of just torn plant leaf using frequency filtering

Biospeckle activity in leaves arise due to the contribution of several phenomena like water content, respiration, transpiration etc. Our present research work deals with the biospeckle activity of a plant leaf using the laser biospeckle technique and wavelet transform just after removal from the plant, to isolate physiological activities like respiration, transpiration etc over water activity for the first time to the best of our knowledge. Visual analyses of biospeckle activities of Mangifera indica and Tabernaemontana divaricata leaves have been done with the help of spectral activity maps obtained using fujii and parameterized geometrical mean of temporal difference algorithms. Mid-vein and other veins are mainly responsible for water transportation whereas different physiological activities occur in both veins and lamina parts of the leaf. As the biospeckle activity due to high water content suppresses the activity due to other physiological phenomena of the leaf, the spectral activity map without any frequency filtering shows the higher activity of the mid-vein than that of the lamina part of the leaf. It has already been established by researchers that the exclusion of lower frequency bands represents physiological activities of biological samples. Spectral activity maps considering the individual frequency bands starting from 13 and 12 onwards in the case of M. indica and T. divaricata leaves are able to represent the physiological phenomena of the leaves respectively. In comparison to the results obtained considering the individual frequency bands, the results obtained by removing the frequency band groups 1–12 (6.25–3.25 Hz frequency range) for M. indica leaf and 1–11 (6.25–3.50 Hz frequency range) for T. divaricata leaf clearly represent the physiological activities over the water activity of those leaves respectively. Also, biospeckle activities using the individual frequency bands along with the exclusion of band groups 13–25 (3.25–0.00 Hz frequency range) and 12–25 (3.50–0.00 Hz frequency range) represent the water activity of the above two leaves respectively.

A dynamic disturbance force measurement system based on array sensor for large moving device in spacecrafts

The control of micro-vibrations is an increasingly significant aspect of the research related to high-precision equipment in spacecraft. As the scale and mass of these vibration sources become larger, the control precision required also increases, and the requirements for the vibration source ground test equipment are thus becoming more demanding. This paper therefore proposes a generalized disturbance force measurement system for large device vibration sources. The use of a redundant array of piezoelectric sensors can significantly increase the size, load capacity and stiffness of the platform. In addition, the D-optimal designs used by the system overcomes the redundant measurement errors introduced by array-based measurements. Based on the above, a more accurate 3D force decoupling expression is obtained using the linear decoupling algorithm of the full regression method. A system prototype is then designed and tested based on the results of this approach. Experimental results show that the system guarantees high load capacity (416 kN) and stiffness, the dynamic relative error within the 8–800 Hz frequency range is less than 3% for a 3D generalized force in the force hammer test, and the relative error of the test system under sinusoidal excitation is within 5%; additionally, the linearity for generalized forces over the full range is within 0.1% full scale and the results are not affected by the characteristics of the measured object.

A novel sound absorber foam based on ethylene propylene diene monomer (EPDM) to absorb low‐frequency waves: Influence of EPDM ethylene content

AbstractIn this study, a partially reticulated foam was fabricated based on ethylene propylene diene monomer rubber to absorb low‐frequency acoustic waves. The effect of ethylene content was studied on the cellular structure, viscoelastic behavior, and sound abortion characteristics. High airflow resistivity of the developed partially reticulated structure, as well as highly deformable cell walls of EPDM foams, led to large dissipation of sound energy at low and medium frequencies. Samples with lower ethylene content which exhibited lower storage modulus and larger pore sizes showed higher viscose motions with superior sound absorption. The foam sample with the lowest ethylene content offered the best sound absorption coefficient with a sharp peak as high as 0.91 within the 500–2500 Hz frequency range. The results imply the role of ethylene content as a molecular structure tool to optimize the acoustic absorption potential of EPDM foam. Besides, the foam samples showed considerable insulation performance, yielding a sound reduction index equal to 26–29 dB. The absorption and reflection of the sound waves were integrated to provide the insulation. Thus, a developed lightweight insulator with high resistance to harsh environmental conditions and great low‐frequency sound absorption could be achieved by structural engineering.

Changes in brain activity with tominersen in early-manifest Huntington's disease.

It is unknown whether alterations in EEG brain activity caused by Huntington’s disease may be responsive to huntingtin-lowering treatment. We analysed EEG recordings of 46 patients (mean age = 47.02 years; standard deviation = 10.19 years; 18 female) with early-manifest Stage 1 Huntington’s disease receiving the huntingtin-lowering antisense oligonucleotide tominersen for 4 months or receiving placebo as well as 39 healthy volunteers (mean age = 44.48 years; standard deviation = 12.94; 22 female) not receiving treatment. Patients on tominersen showed increased resting-state activity within a 4–8 Hz frequency range compared with patients receiving placebo (cluster-based permutation test, P < 0.05). The responsive frequency range overlapped with EEG activity that was strongly reduced in Huntington’s disease compared with healthy controls (cluster-based permutation test, P < 0.05). The underlying mechanisms of the observed treatment-related increase are unknown and may reflect neural plasticity as a consequence of the molecular pathways impacted by tominersen treatment.Hawellek et al. report that patients with Huntington’s disease treated with the huntingtin-lowering antisense oligonucleotide tominersen exhibited increased EEG power in the theta/alpha frequency range. The underlying mechanisms of the observed changes are unknown and may reflect neural plasticity as a consequence of the molecular pathways impacted by tominersen treatment.

The Acoustic Characteristics of Vocal Twang

The Acoustic Characteristics of Vocal Twang Ingo R. Titze (bio) VOICE RESEARCH AND TECHNOLOGY Vocalists are capable of imitating many of the sound qualities of musical instruments. As with impersonation of sounds other humans make, a caricature of the main feature of the instrumental sound is produced. Vocal timbre can be flute-like, brass-like, or percussive. Often the desired sound quality is that of the instruments that accompany the voice. Give the vastly different geometry and material properties of the human airway compared to those of musical instruments, only one or two acoustic features can usually be imitated. The word “twang” comes from the sound of a plucked guitar string. There is little in common between guitar strings transmitting sound to wooden plates and vocal folds transmitting sound through a 17 cm vocal tract, yet a common feature can be the clustering of frequencies produced. Woodhouse published frequency spectra of plucked guitar strings. Regardless of the pitch produced, the dominant harmonics clustered around 1500–2000 Hz. The fundamental frequency was never the dominant one.1 Such a frequency spectrum can be approximated by shaping the vocal tract such that both the epilaryngeal and the pharyngeal airway are narrow. The bottom row of Figure 1 shows this airway configuration in comparison to other shapes that produce different voice qualities, such as neutral, yawn, ring, and call. On the right panel, the input impedance to the vocal tract is shown for each configuration in the 100–2000 Hz region. The thin line is input resistance and the thick line is input reactance. High positive reactance means that harmonics are reinforced by the vocal tract. Note that twang has the highest reactance between 800 Hz and 1600 Hz. (The ring configuration has its highest reactance in the 3000–4000 Hz range, not shown in Figure 1). With a variety of tongue and lip configurations, the impedance peaks in the 1000–2000 Hz range can be moved up and down, as well as closer together or farther apart. Saldias et al. have shown midsagittal airway images that clearly show the narrowing in the epilaryngeal and pharyngeal regions in twang phonation. They have also shown that the corresponding spectrum has a broad peak in the 1000–2000 Hz region.2 A second feature of twang is nonsteadiness. The spectrum of a plucked string does not remain constant. It is transient as the sound dies out. A sharp twang drifts to a more mellow twang. A singer can imitate this transient quality by keeping the vowel or vocal fold adduction variable. Country singers often [End Page 613] make their vowels more speech-like, drifting from one vowel to another with co-articulation. This is in contrast to classical singers, who often maintain a steady voice quality, thereby mimicking steady tone instruments, such as flutes, brasses, and bowed strings. Click for larger view View full resolution Figure 1. (left) Airway shapes and (right) corresponding vocal tract input impedance over a 100–2000 Hz frequency range. Thin lines are resistances and thick lines are reactances. This author has had multiple conversations with singing teachers about what constitutes “twang” in the industry. In an audition, singers may be asked to produce a twang sound, but it comes out more like a belt or a pressed voice. My advice would be to listen carefully to the sound of a plucked steel string. Imitate that sound first in isolation, then embed that quality into running speech, and finally “sang a sawng” with it. Ingo R. Titze NOTES 1. J. Woodhouse, “Plucked Guitar Transients: Comparison of Measurements and Synthesis,” Acta Acustica united with Acustica 90, no. 5 (September/October 2004): 945–965. 2. Marcelo Saldías, Anne-Maria Laukkanen, Marco Guzmán, Gonzalo, Maranda, Justin, Stoney, Paavo Alku, and Johan Sundberg, “The Vocal Tract in Loud Twang-Like Singing While Producing High and Low Pitches,” Journal of Voice 35, no. 5 (September 2021): 807.e1–807.e23. Copyright © 2022 National Association of Teachers of Singing, Inc

3D Phase tensor inversion and Joint inversion using impedance and phase tensor components aiming better subsurface mapping and interpretation in Dhanjori basin, Singhbhum craton, eastern India

Dhanjori formation, a significant member of Singhbhum Craton, Eastern India, is well-known for its complex mineralogical character and huge content of Au-mineralization. This 2.1 Ga old Paleoproterozoic formation is composed of siliciclastic metasedimentary rocks interlayered with mafic/ultramafic volcanic rocks. Traces of gold has been spotted by many researchers in the sulfide-hosted mafic-ultramafic volcanic rocks and quartz pebble conglomerate units by different studies. Regional Audio Magnetotelluric (AMT) survey was conducted in 10 kHz–10 Hz frequency range over various lithological units of Dhanjori and adjacent Iron Ore Group. The key challenge faced during the analysis of magnetotelluric (MT) data is due to the presence of near-surface heterogeneities. The amplitude of the MT response gets distorted by galvanic effects which further create difficulties in modelling and inversion. If the effect is not removed in advance, it might lead to erroneous subsurface modelling and interpretations. On the contrary, the phase tensor data does not show any change in values even in the presence of galvanic distortion. Though phase tensors are the computed values from impedance tensor, still the response is free from any shallow level ambiguities unlike impedance data. We have performed 3-D inversion of phase tensor data to generate a conductivity model of Dhanjori basin. The objective was to verify whether the inclusion of phase tensor components in the inversion routine was able to provide some extra information that might add value to the analysis. Model from phase tensor inversion indicates only relative variation in the subsurface conductivity structure due to lack of amplitude information in the data. Hence, we also performed 3D joint inversion including both impedance and phase tensor components for obtaining the final conductivity model of Dhanjori to recover the absolute subsurface conductivity structure unaffected by galvanic distortion. Correlation of the conductivity model with available geoscientific information in Dhanjori and adjacent geological units helped us to relate the conductors to the sulfide mineralization prospect.

Abnormal neural oscillations in clinical high risk for psychosis: a magnetoencephalography method study

BackgroundNeural oscillations directly reflect the rhythmic changes of brain activities during the resting state or while performing specific tasks. Abnormal neural oscillations have been discovered in patients with schizophrenia. However,...

Oxygen-vacancy-ordering-induced metal-insulator transition in MgO single crystals

Dielectric properties of MgO single crystal were investigated in the temperature range of 300–1100 K and frequency range of 4x101-106 Hz. The sample exhibits intrinsic dielectric response below 400 K, two oxygen-vacancy-related phase transitions around 800 K, and thermally activated relaxation above 815 K. Impedance analysis revealed that the first phase transition is accompanied by an electronic phase transition of metal–insulator transition (MIT) and abnormal dielectric relaxation. These results can be well understood based on the scenario of oxygen-vacancy-ordering process. The first and second phase transitions are related to oxygen vacancies changing from disordered state to ordered state and then returning back to disordered state, respectively. The appearance of oxygen-vacancy-ordered phase leads to grain-boundary-like interfaces between the ordered phase and the surrounding medium, which in turn yields positive temperature coefficient of resistance giving rise to the MIT effect and the abnormal dielectric relaxation.

Combining translational and rotational seismic motions to invert local-scale seismic data for time-variable moment tensors: do rotational motions help for high-frequency seismic data produced by underground explosions?

SUMMARY We present an analysis of combining translational and rotational seismic data in an inversion for the time-variable source time functions corresponding to the components of the seismic moment tensor. We conduct a series of numerical experiments where the data are simulated by a combination of an underground explosion and a co-located double couple shear source and recorded on surface-mounted seismometers within 1–2 km of the source. The experiments are designed to mimic explosion seismology experiments, and thus the data are in the 1–10 Hz frequency range and contain very few surface waves. We use a Monte Carlo method to propagate Earth model uncertainty into the estimates of seismic source parameters. In our experiments, we find that the uncertainty of the estimated seismic source parameters increases when we add rotational seismic motions to the inversion when using a constant number of data channels. In this case, the increased degree of uncertainty in the final results is most likely due to the near-surface Earth model uncertainty that we introduce in our simulations. However, for a fixed number of seismic stations, adding rotational seismic motions to the inversion acts to decrease the uncertainty of the estimated seismic source parameters, most likely due to the increase in the number of data channels used in the inversion.

Characteristics of ULF Magnetic Fields in the 3D Inhomogeneous Earth‐Ionosphere Waveguide

AbstractWe develop an algorithm for calculating the characteristics of the magnetic field of signals in the frequency range of (0.1–20) Hz in the horizontally and vertically inhomogeneous spherical Earth‐ionosphere waveguide. This algorithm involves calculations of the surface impedance of an inhomogeneous ionosphere. The frequency dependences of the amplitude, phase and polarization of the magnetic field generated by a horizontal magnetic dipole were analyzed. It is shown that the horizontal inhomogeneity of the Earth‐ionosphere waveguide can significantly affect the frequency dependence of the amplitude and polarization of the magnetic field, increasing the degree of circular polarization. The horizontal inhomogeneity only slightly influences the results in daytime conditions. The most noticeable difference in the amplitude dependences of the magnetic components and large phase shifts (up to 40°) are observed when the terminator passes through the geodetic line connecting the source and receiver, and in the presence of sporadic layers with a horizontally inhomogeneous structure along the low‐frequency wave propagation path. We compare the calculation results with the magnetic pulsations recorded at Nurmijarvi station during the 2001 campaigns of Kola Peninsula ultra low frequency emitter operation. The obtained results make it possible to qualitatively explain peculiarities of the amplitude and polarization spectra of the artificial magnetic signals recorded in this campaigns that are not explained within the framework of the flat homogeneous waveguide model.

Timing of brain entrainment to the speech envelope during speaking, listening and self-listening

⁠This study investigates the dynamics of speech envelope tracking during speech production, listening and self-listening. We use a paradigm in which participants listen to natural speech (Listening), produce natural speech (Speech Production), and listen to the playback of their own speech (Self-Listening), all while their neural activity is recorded with EEG. After time-locking EEG data collection and auditory recording and playback, we used a Gaussian copula mutual information measure to estimate the relationship between information content in the EEG and auditory signals. In the 2–10 Hz frequency range, we identified different latencies for maximal speech envelope tracking during speech production and speech perception. Maximal speech tracking takes place approximately 110 ms after auditory presentation during perception and 25 ms before vocalisation during speech production. These results describe a specific timeline for speech tracking in speakers and listeners in line with the idea of a speech chain and hence, delays in communication.

A Fish and Dolphin Biophony in the Boat Noise-Dominated Soundscape of the Cres-Lošinj Archipelago (Croatia)

Spatio-temporal variability of marine soundscapes reflects environmental dynamics and local habitat health. This study characterizes the coastal soundscape of the Cres-Lošinj Natura 2000 Site of Community Importance, encompassing the non-tourist (11–15 March 2020) and the tourist (26–30 July 2020) season. A total of 240 h of continuous recordings was manually analyzed and the abundance of animal vocalizations and boat noise was obtained; sound pressure levels were calculated for the low (63–2000 Hz) and high (2000–20,000 Hz) frequency range. Two fish sound types were drivers of both seasonal and diel variability of the low-frequency soundscape. The first is emitted by the cryptic Roche’s snake blenny (Ophidion rochei), while the second, whose emitter remains unknown, was previously only described in canyons and coralligenous habitats of the Western Mediterranean Sea. The high-frequency bands were characterized by bottlenose dolphin (Tursiops truncatus) vocalizations, indicating dolphins’ use of area for various purposes. Boat noise, however, dominated the local soundscape along the whole considered periods and higher sound pressure levels were found during the Tourist season. Human-generated noise pollution, which has been previously found 10 years ago, is still present in the area and this urges management actions.

Effect of Annealing and Ion Beam Irradiation on AC Electrical Properties for Gold Sputtered PM-355

Deposition of different gold thickness on PM-355 cleaned by ethanol forming thin films using magnetron sputtering. Gold layer with thickness 300, 400, 500, 700, 1000, 1300, and 1500 nm were deposited to prepare Au / PM-355 thin films. Then, ac electrical properties response of thin films for a wide frequency range 20Hz - 5MHz were measured at roomtemperature. Meanwhile, the measurements of ac conductivity, dielectric constant, and dielectric loss factor were plotted at different frequencies to determine the optimum thickness. Hence, the comparison was done between optimum Au thickness thin films cleaned by two organic solvents and ethanol before annealing at different frequencies. Also, study the effect of annealing and ion beam that extracted radially from conical anode and disc cathode ion source on optimum Au thickness thin film electrical properties. It is found that the annealing increases both dielectric constant, dielectric loss, and ac conductivity of optimum Au thin film at different frequencies. Despite, the nitrogen ion beam effected on these thin films by decreasing the dielectric constant and ac conductivity for all thin films except the chloroform one. Finally, study the comparison between the annealing and followed by ion irradiation thin films. It is noticed the decrease in ac electrical conductivity and dielectric constant at different frequencies.