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3 Tesla magnetic resonance imaging noise in standard head and neck sequence does not cause temporary threshold shift in high frequency

Lim EY, Tang IP, Peyman M, Ramli N, Narayanan P, Rajagopalan R

Eur Arch Otorhinolaryngol, 2015 Nov;272(11):3109-13.
PMID: 25205300 DOI: 10.1007/s00405-014-3232-y

High acoustic noise level is one of the unavoidable side effects of 3 T magnetic resonance imaging (MRI). A case of hearing loss after 3 T MRI has been reported in this institution and hence this study. The objective of this study was to determine whether temporary threshold shift (TTS) in high frequency hearing occurs in patients undergoing 3 T MRI scans of the head and neck. A total of 35 patients undergoing head and neck 3 T MRI for various clinical indications were tested with pure tone audiometry in different frequencies including high frequencies, before and after the MRI scan. Any threshold change from the recorded baseline of 10 dB was considered significant. All patients were fitted with foamed 3 M earplugs before the procedure following the safety guidelines for 3 T MRI. The mean time for MRI procedure was 1,672 s (range 1,040-2,810). The noise dose received by each patient amounted to an average of 3,906.29% (1,415-9,170%). The noise dose was derived from a normograph used by Occupational Noise Surveys. This was calculated using the nomograph of L eq, L EX, noise dose and time. There was no statistically significant difference between the hearing threshold before and after the MRI procedures for all the frequencies (paired t test, P > 0.05). For patients using 3 M foamed earplugs, noise level generated by 3 T MRI during routine clinical sequence did not cause any TTS in high frequency hearing.

Matched MeSH terms: Hearing Loss, Noise-Induced/etiology*; Noise*
Digital noise reduction in hearing aids and its acoustic effect on consonants /s/ and /z/

Chong FY, Jenstad LM

Med J Malaysia, 2018 12;73(6):365-370.
PMID: 30647205

INTRODUCTION: Modulation-based noise reduction (MBNR) is one of the common noise reduction methods used in hearing aids. Gain reduction in high frequency bands may occur for some implementations of MBNR and fricatives might be susceptible to alteration, given the high frequency components in fricative noise. The main objective of this study is to quantify the acoustic effect of MBNR on /s, z/.
METHODS: Speech-and-noise signals were presented to, and recorded from, six hearing aids mounted on a head and torso simulator. Test stimuli were nonsense words mixed with pink, cafeteria, or speech-modulated noise at 0 dB SNR. Fricatives /s, z/ were extracted from the recordings for analysis.
RESULTS: Analysis of the noise confirmed that MBNR in all hearing aids was activated for the recordings. More than 1.0 dB of acoustic change occurred to /s, z/ when MBNR was turned on in four out of the six hearing aids in the pink and cafeteria noise conditions. The acoustics of /s, z/ by female talkers were affected more than male talkers. Significant relationships between amount of noise reduction and acoustic change of /s, z/ were found. Amount of noise reduction accounts for 42.8% and 16.8% of the variability in acoustic change for /s/ and /z/ respectively.
CONCLUSION: Some clinically-available implementations of MBNR have measurable effects on the acoustics of fricatives. Possible implications for speech perception are discussed.

Matched MeSH terms: Noise
Fulltext A Heuristic Approach for Optical Transceiver Placement to Optimize SNR and Illuminance Uniformities of an Optical Body Area Network

Masroor K, Jeoti V, Drieberg M, Cheab S, Rajbhandari S

Sensors (Basel), 2021 Apr 22;21(9).
PMID: 33922288 DOI: 10.3390/s21092943

The bi-directional information transfer in optical body area networks (OBANs) is crucial at all the three tiers of communication, i.e., intra-, inter-, and beyond-BAN communication, which correspond to tier-I, tier-II, and tier-III, respectively. However, the provision of uninterrupted uplink (UL) and downlink (DL) connections at tier II (inter-BAN) are extremely critical, since these links serve as a bridge between tier-I (intra-BAN) and tier-III (beyond-BAN) communication. Any negligence at this level could be life-threatening; therefore, enabling quality-of-service (QoS) remains a fundamental design issue at tier-II. Consequently, to provide QoS, a key parameter is to ensure link reliability and communication quality by maintaining a nearly uniform signal-to-noise ratio (SNR) within the coverage area. Several studies have reported the effects of transceiver related parameters on OBAN link performance, nevertheless the implications of changing transmitter locations on the SNR uniformity and communication quality have not been addressed. In this work, we undertake a DL scenario and analyze how the placement of light-emitting diode (LED) lamps can improve the SNR uniformity, regardless of the receiver position. Subsequently, we show that using the principle of reciprocity (POR) and with transmitter-receiver positions switched, the analysis is also applicable to UL, provided that the optical channel remains linear. Moreover, we propose a generalized optimal placement scheme along with a heuristic design formula to achieve uniform SNR and illuminance for DL using a fixed number of transmitters and compare it with an existing technique. The study reveals that the proposed placement technique reduces the fluctuations in SNR by 54% and improves the illuminance uniformity up to 102% as compared to the traditional approach. Finally, we show that, for very low luminous intensity, the SNR values remain sufficient to maintain a minimum bit error rate (BER) of 10-9 with on-off keying non-return-to-zero (OOK-NRZ) modulation format.

Matched MeSH terms: Signal-To-Noise Ratio
Fulltext Performance of ultra-wideband systems in the presence of WiFi and 3G signals

Rashid, A.S., Khatun, S., Ali, B.M., Khazani, A.M.

ASM Science Journal, 2008;2(1):13-22.
MyJurnal

An analysis of the power spectral density of ultra-wideband (UWB) signals is presented in order to evaluate the effects of cumulative interference from multiple UWB devices on victim narrowband systems in their overlay bands like WiFi (i.e. IEEE802.11a) and 3rdG systems (Universal mobile telecommunications system/wideband code division multiple access). In this paper, the performances are studied through the bit-error-rate as a function of signal-to-noise ratio as well as signal-to-interference power ratio using computer simulation and exploiting the realistic channel model (i.e. modified Saleh-Valenzuela model). Several modifications of a generic Gaussian pulse waveform with lengths in the order of nanoseconds were used to generate UWB spectra. Different kinds of pulse modulation (i.e. antipodal and orthogonal) schemes were also taken into account.

Matched MeSH terms: Signal-To-Noise Ratio
Fulltext Er3+/Yb3+ co-doped fibre amplifier demonstrates significant gain enhancement with improved noise figure

Muhd-Yassin, S.Z., Harun, S.W., Ahmad, H., Abd-Rahman, M.K.

ASM Science Journal, 2008;2(2):163-168.
MyJurnal

An efficient erbium/ytterbium co-doped fibre amplifier was demonstrated by using a dual-stage partial doublepass structure with a band-pass filter (BPF). The amplifier achieved the maximum small signal gain of 56 dB and the corresponding noise figure of 4.66 dB at 1536 nm with an input signal power and total pump power of –50 dBm and 140 mW, respectively. Compared with a conventional single-stage amplifier, the maximum gain enhancement of 16.99 dB was obtained at 1544 nm with the corresponding noise figure was improved by 2 dB. The proposed amplifier structure only used a single pump source with a partial double pass scheme to provide a high gain and dual-stage structure to provide the low noise figure.

Matched MeSH terms: Noise
Fulltext Evaluation of the effect of radio frequency interference on global positioning system (GPS) receivers via GPS simulation

Dinesh, S., Faudzi, M.M., Rafidah, M., Shakhira, B.N.I., Robiah, A.S., Shalini, S.S., et al.

ASM Science Journal, 2014;8(1):11-20.
MyJurnal

In this study, Global Positioning System (GPS) simulation was employed to study the effect of radio frequency interference (RFI) on two hand-held GPS receivers; Garmin GPSmap 60CSx (evaluated GPS receiver) and Garmin GPSmap 60CS (reference GPS receiver). Both GPS receivers employed the GPS L1 coarse acquisition (C/A) signal. It was observed that the interference signal power levels required to affect the location fixes of the GPS receivers were significantly high compared to the corresponding GPS signal power levels. The noiselike C/A code structure, which modulated the L1 signal over a 2 MHz bandwidth, allowed for the signal to be received at low levels of interferences. The evaluated GPS receiver had better RFI operability as compared to the reference GPS receiver. This is because the evaluated GPS receiver had higher receiver sensitivity, allowing it to have increased carrier-to-noise density (C/N0) levels for GPS satellites tracked by the receiver. The absence of other error parameters, including ionospheric and tropospheric delays, satellite clock, ephemeris and multipath errors, and unintentional signal interferences and obstructions, resulted in the required minimum jamming power levels in this study to be significantly higher as compared to field evaluations. These minimum jamming power levels vary with location and time. This was due to the GPS satellite constellation being dynamic, causing varying GPS satellite geometry over location and time, resulting in the minimum required GPS jamming power levels being location / time dependent. In general, the lowest minimum jamming power levels were observed for readings with the highest position dilution of precision (PDOP) values, and vice versa.

Matched MeSH terms: Noise
Fulltext Optical tomography: real time image reconstruction for various flow regimes in gravity flow conveyor

Abdul Rahim, R., Pang, J.F., Chan, K.S., Leong, L.C., Fazalul Rahiman, M.H.

ASM Science Journal, 2007;1(1):27-36.
MyJurnal

In this study, real-time imaging was monitored for flowing solid particles when various baffles were created to block certain areas of the pipe. The generated flow regimes were full-flow, three-quarter-flow, half-flow and quarter-flow. A vertical pneumatic conveyor was designed to hold a 85 mm inner diameter pipeline. The four projection optical tomography systems used, applied the parallel beam projection approach and use infrared light sources so that the sensor was free of noise from the surrounding visible light source. The two orthogonal and two rectilinear projections were axial, but ideally they should have been in the same layer. The sensor readings could be related to the varying light intensity effects of the dropping particles and were used to provide cross-sectional distribution information for the conveyor. By using computer programming, the information was reconstructed to produce coloured images and concentration was obtained by reference to a colour code. The results obtained from this study showed how imaged flow followed the artificial flow regime. This study could benefit industrial production lines in maintaining the desired flow rates.

Matched MeSH terms: Noise
Fulltext Comparison studies of resolution and noise properties between drum type and laser type film digitization systems

Khairul Anuar Mohd Salleh, Ab. Razak Hamzah, Wan Muhammad Saridan Wan Hassan

Journal of Nuclear and Related Technologies, 2008;2008(2):35-45.
MyJurnal

Developments of computer technology and image processing have shifted conventional industrial radiography application to industrial digital radiography (IDR) system. In this study, two types of IDR modules for non destructive testing (NDT), namely drum- and laser- type film digitizer with 50 μm pixel pitch have been evaluated for NDT applications. The modulation transfer function (MTF) and noise power spectrum (NPS) measurement were adapted to evaluate the image quality of IDR images. Results shown the averaged MTF for drum- and laser- type film digitizer at 20% modulation were 6.15 cycles/mm and 6.55 cycles/mm respectively. For NPS measurement and calculation, the result obtained shows that drum type film digitizer produced higher noise then laser type film digitizer. The study shows that the laser type film digitizer is the best system to be used for film digitization purposes because the MTF result shows that it modulates better than drum type and has the lowest and stable NPS.

Matched MeSH terms: Noise
Overcoming Limitations of LoRa Physical Layer in Image Transmission

Jebril AH, Sali A, Ismail A, Rasid MFA

Sensors (Basel), 2018 Sep 27;18(10).
PMID: 30262793 DOI: 10.3390/s18103257

As a possible implementation of a low-power wide-area network (LPWAN), Long Range (LoRa) technology is considered to be the future wireless communication standard for the Internet of Things (IoT) as it offers competitive features, such as a long communication range, low cost, and reduced power consumption, which make it an optimum alternative to the current wireless sensor networks and conventional cellular technologies. However, the limited bandwidth available for physical layer modulation in LoRa makes it unsuitable for high bit rate data transfer from devices like image sensors. In this paper, we propose a new method for mangrove forest monitoring in Malaysia, wherein we transfer image sensor data over the LoRa physical layer (PHY) in a node-to-node network model. In implementing this method, we produce a novel scheme for overcoming the bandwidth limitation of LoRa. With this scheme the images, which requires high data rate to transfer, collected by the sensor are encrypted as hexadecimal data and then split into packets for transfer via the LoRa physical layer (PHY). To assess the quality of images transferred using this scheme, we measured the packet loss rate, peak signal-to-noise ratio (PSNR), and structural similarity (SSIM) index of each image. These measurements verify the proposed scheme for image transmission, and support the industrial and academic trend which promotes LoRa as the future solution for IoT infrastructure.

Matched MeSH terms: Signal-To-Noise Ratio
Fulltext Bilateral Heschl’s Gyrus display non-reciprocity in connectivity during the performance of simple arithmetic addition task

Yusoff, A.N., Te, L.H., Mukari, S.Z.M., Abd Hamid, A.I.

Jurnal Sains Kesihatan Malaysia, 2016;14(1):37-45.
MyJurnal

Heschl’s gyrus (HG) is known to interact with other auditory related areas of the same hemisphere during the performance
of an auditory cognitive task. However, the information about how it interacts with the opposite HG is still lacking.
The aim of this study was to investigate the psychophysiologic interaction (PPI) between the bilateral HG during a
simple arithmetic addition task and to verify the role of noise as an experimental factor that would modulate the PPI.
Functional magnetic resonance imaging (fMRI) scans were performed on eighteen healthy participants, in which a
single-digit addition task were solved during in-quiet (AIQ) and in-noise (AIN) conditions. The fMRI data were analysed
using Statistical Parametric Mapping (SPM8). The interaction between the bilateral HG was investigated using PPI
analysis. The response in right HG was found to be linearly influenced by the activity in left HG, vice-versa, for both
in-quiet and in-noise conditions. The connectivity from right to left HG in noisy condition seemed to be modulated
by noise, while the modulation is relatively small oppositely, indicating a non-reciprocal behavior. A two-way PPI
model between right and left HG is suggested. The connectivity from right to left HG during a simple addition task in
noise is driven by a higher ability of right HG to perceive the stimuli in a noisy condition. Both the bilateral HGs took
part in the cognitive processes of arithmetic addition from which the interactions between the two were found to be
different in noise.

Matched MeSH terms: Noise
Fulltext Noise Eliminated Ensemble Empirical Mode Decomposition Scalogram Analysis for Rotating Machinery Fault Diagnosis

Faysal A, Ngui WK, Lim MH, Leong MS

Sensors (Basel), 2021 Dec 04;21(23).
PMID: 34884120 DOI: 10.3390/s21238114

Rotating machinery is one of the major components of industries that suffer from various faults due to the constant workload. Therefore, a fast and reliable fault diagnosis method is essential for machine condition monitoring. In this study, noise eliminated ensemble empirical mode decomposition (NEEEMD) was used for fault feature extraction. A convolution neural network (CNN) classifier was applied for classification because of its feature learning ability. A generalized CNN architecture was proposed to reduce the model training time. A sample size of 64×64×3 pixels RGB scalograms are used as the classifier input. However, CNN requires a large number of training data to achieve high accuracy and robustness. Deep convolution generative adversarial network (DCGAN) was applied for data augmentation during the training phase. To evaluate the effectiveness of the proposed feature extraction method, scalograms from related feature extraction methods such as ensemble empirical mode decomposition (EEMD), complementary EEMD (CEEMD), and continuous wavelet transform (CWT) are classified. The effectiveness of scalograms is also validated by comparing the classifier performance using grayscale samples from the raw vibration signals. All the outputs from bearing and blade fault classifiers showed that scalogram samples from the proposed NEEEMD method obtained the highest accuracy, sensitivity, and robustness using CNN. DCGAN was applied with the proposed NEEEMD scalograms to further increase the CNN classifier's performance and identify the optimal number of training data. After training the classifier using augmented samples, the results showed that the classifier obtained even higher validation and test accuracy with greater robustness. The proposed method can be used as a more generalized and robust method for rotating machinery fault diagnosis.

Matched MeSH terms: Noise
Fulltext Noise exposure effect on testicular histology, morphology and on male steroidogenic hormone

Swami CG, Ramanathan J, Charan Jeganath C

Malays J Med Sci, 2007 Jul;14(2):28-35.
PMID: 23515367 MyJurnal

The noise stress, after it passes through the hearing apparatus, not only affects the auditory apparatus but also other body functions. The alterations in the levels of cortical hormone, adrenocorticosterone, nor-epinephrine hormone (which are primarily considered as stress hormones) on follicular stimulating hormone, testosterone, and lutinizing hormone were reported in relation with stress. Male albino rats weighing 200 to 250 grams were exposed to 100 dB of noise for one hour and three hours in acute group and daily one hour exposure for 60 day, and 90 day in chronic group. The serum testosterone levels were measured in these animals. There was significant reduction in serum testosterone levels and this was similar with earlier reports. The tissues were collected for light and confocal microscopic study. 100dB of traffic noise exposure of varying duration had definite permanent effect on testicular histology and morphology and on the male sex hormone. The adaptation mechanism was noticed at the hormonal level only but the structural changes noticed were definite and permanent. The agglutinated dead sperms revealed the possibility of infertily when chronically exposed to noise stress.

Matched MeSH terms: Noise
Fulltext Hearing loss and contributing factors among airport workers in Malaysia

Nasir MH, Rampal KG

Med J Malaysia, 2012 Feb;67(1):81-6.
PMID: 22582554 MyJurnal

Sensorineural hearing loss is a common and important source of disability among the workers and often caused by occupational noise exposure. Aims of the study were to determine the prevalence and contributing factors of hearing loss among airport workers. A cross-sectional study was carried out at an airport in Malaysia. This study used stratified sampling method that involved 358 workers who were working in 3 different units between November 2008 and March 2009. Data for this study were collected by using questionnaires eliciting sociodemographic, occupational exposure history (previous and present), life-style including smoking habits and health-related data. Otoscopic and pure-tone audiometric tests were conducted for hearing assessment. Noise exposure status was categorize by using a noise logging dosimeter to obtain 8-hour Time-Weighted Average (TWA). Data was analyzed by using SPSS version 12.0.1 and EpiInfo 6.04. The prevalence of hearing loss was 33.5%. Age >40 years old (aOR 4.3, 95%CI 2.2-8.3) is the main risk factors for hearing loss followed by duration of noise exposure >5 years (aOR 2.5, 95%CI 1.4-4.7), smoking (aOR 2.1, 95%CI 1.2-3.4), duration of service >5 years (aOR 2.1, 95%CI 1.1-3.9), exposure to explosion (aOR 6.1, 95%CI 1.3-29.8), exposure to vibration (aOR 2.2, 95%CI 1.1-4.3) and working in engineering unit (aOR 5.9, 95%CI 1.1-30.9). The prevalence rate ratio of hearing loss for nonsmokers aged 40 years old and younger, smokers aged 40 years old and younger, non-smokers older than 40 years old and smokers older than 40 years old was 1.0, 1.7, 2.8 and 4.6 respectively. This result contributes towards better understanding of risk factors for hearing loss, which is relatively common among Malaysian workers.

Matched MeSH terms: Hearing Loss, Noise-Induced/etiology*; Hearing Loss, Noise-Induced/epidemiology
Screening of dental staff nurses for noise induced hearing loss

Daud MK, Noh NF, Sidek DS, Abd Rahman N, Abd Rani N, Zakaria MN

B-ENT, 2011;7(4):245-9.
PMID: 22338236

The effect of noise on employees of dental clinics is debatable. The purposes of this study were to determine the intensity and frequency components of dental instruments used by dental staff nurses and the prevalence of noise induced hearing loss.

Matched MeSH terms: Hearing Loss, Noise-Induced/diagnosis; Hearing Loss, Noise-Induced/epidemiology*
The effectiveness of applying different permissible exposure limits in preserving the hearing threshold level: a systematic review

Sayapathi BS, Su AT, Koh D

J Occup Health, 2014;56(1):1-11.
PMID: 24270928

OBJECTIVES: A systematic review was conducted to identify the effectiveness of different permissible exposure limits in preserving the hearing threshold level. This review compared the limits of the US National Institute of Occupational Safety and Health with those of the US Occupational Safety and Health Administration. The prevalence of occupational noise-induced hearing loss is on an increasing trend globally. This review was performed to reduce the prevalence of noise-induced hearing loss.
METHODS: We searched 3 major databases, i.e., PubMed, Embase and Lippincott Williams & Wilkins Journals@Ovid, for studies published up until 1May 2013 without language restrictions. All study designs were included in this review. The studies were identified and retrieved by two independent authors.
RESULTS: Of 118 titles scanned, 14 duplicates were removed, and a total of 13 abstracts from all three databases were identified for full-text retrieval. From the full text, eight articles met the inclusion criteria for this systematic review. These articles showed acceptable quality based on our scoring system. Most of the studies indicated that temporary threshold shifts were much lower when subjects were exposed to a noise level of 85 dBA or lower.
CONCLUSIONS: There were more threshold shifts in subjects adopting 90 dBA compared with 85 dBA. These temporary threshold shifts may progress to permanent shifts over time. Action curtailing noise exposure among employees would be taken earlier on adoption of 85 dBA as the permissible exposure limit, and hence prevalence of noise-induced hearing loss may be reduced.

Matched MeSH terms: Hearing Loss, Noise-Induced/epidemiology; Hearing Loss, Noise-Induced/prevention & control*; Noise, Occupational/adverse effects*; Noise, Occupational/prevention & control
A study on compliance to hearing conservation programme among industries in Negeri Sembilan, Malaysia

Nor Saleha IT, Noor Hassim I

Ind Health, 2006 Oct;44(4):584-91.
PMID: 17085919

Noise is one of the hazards faced by workers. A cross-sectional study was conducted among industries in Negeri Sembilan with the objective to assess their compliance to Hearing Conservation Programme (HCP). The other objectives of this study were to determine the factors influencing it and to show the industries' compliance to each element of the programme. It was also to identify the association between compliance to HCP and the prevalence of hearing impairment and standard threshold shift. Data for this study were collected using questionnaires sent by mail and also the results of the latest audiometric tests. A total of 167 industries were analysed for this study. It was found that 41.3% of these industries fully complied to the programme. It was also found that the industries preferred to provide hearing protection device (92.8%) and least complied to noise control (61.1%). There were significant associations (p<0.05) between compliance and number of employees, status of ownership and the presence of officer in charge of hearing conservation programme. Having at least 150 employees actually raised the compliance to HCP in two folds (beta = 0.717, OR = 2.048, C.I 95% = 1.063 to 3.944). The prevalences of hearing impairment and standard threshold shift were 23.9% and 5.2% respectively. There was no significant association between the prevalence for hearing impairment and compliance to HCP. The prevalence for standard threshold shift was inversely related to compliance. This study showed that compliance percentage need to be improved as an effort to prevent the hearing problems among workers exposed to noise.

Matched MeSH terms: Hearing Loss, Noise-Induced/etiology; Hearing Loss, Noise-Induced/epidemiology; Hearing Loss, Noise-Induced/prevention & control*; Noise, Occupational/adverse effects*
Fulltext A novel sample based quadrature phase shift keying demodulator

Mohamed Moubark A, Ali SH

ScientificWorldJournal, 2014;2014:107831.
PMID: 25197687 DOI: 10.1155/2014/107831

This paper presents a new practical QPSK receiver that uses digitized samples of incoming QPSK analog signal to determine the phase of the QPSK symbol. The proposed technique is more robust to phase noise and consumes up to 89.6% less power for signal detection in demodulation operation. On the contrary, the conventional QPSK demodulation process where it uses coherent detection technique requires the exact incoming signal frequency; thus, any variation in the frequency of the local oscillator or incoming signal will cause phase noise. A software simulation of the proposed design was successfully carried out using MATLAB Simulink software platform. In the conventional system, at least 10 dB signal to noise ratio (SNR) is required to achieve the bit error rate (BER) of 10(-6), whereas, in the proposed technique, the same BER value can be achieved with only 5 dB SNR. Since some of the power consuming elements such as voltage control oscillator (VCO), mixer, and low pass filter (LPF) are no longer needed, the proposed QPSK demodulator will consume almost 68.8% to 99.6% less operational power compared to conventional QPSK demodulator.

Matched MeSH terms: Signal-To-Noise Ratio
Hearing loss after noise exposure

Govindaraju R, Omar R, Rajagopalan R, Norlisah R, Kwan-Hoong N

Auris Nasus Larynx, 2011 Aug;38(4):519-22.
PMID: 21236610 DOI: 10.1016/j.anl.2010.12.006

The higher field strength magnetic resonance imaging (MRI) such as 3 Tesla (T) and above generates noise that has potential detrimental effects on the hearing. Temporary threshold shifts following MRI examination have been reported for MRI with lower field strength. Such effect, however, have not been reported so far for a 3T MRI. We report a case that exemplifies the possible detrimental effects of a 3 T MRI generated noise on the auditory system. Our patient underwent investigation of his chronic backache in a 3 T MRI unit and developed hearing loss and tinnitus post-MRI examination. Hearing assessment was done using pure tone audiogram, distortion product otoacoustic emission (DPOAE) and brainstem electrical response audiometry (BERA) which revealed a unilateral sensorineural hearing loss which recovered within 3 days. However the tinnitus persisted. This is possibly a case of temporary threshold shift following noise exposure. However a sudden sensorineural hearing loss remains the other possibility.

Matched MeSH terms: Hearing Loss, Noise-Induced/diagnosis; Hearing Loss, Noise-Induced/etiology*; Hearing Loss, Noise-Induced/physiopathology
Optimization of dose and image quality of paediatric cardiac catheterization procedure

Lubis LE, Bayuadi I, Pawiro SA, Ng KH, Bosmans H, Soejoko DS

Phys Med, 2015 Nov;31(7):659-68.
PMID: 26050060 DOI: 10.1016/j.ejmp.2015.05.011

The purpose of this study is to quantify the quality of the available imaging modes for various iodine-based contrast agent concentration in paediatric cardiology. The figure of merit (FOM) was defined as the squared signal to noise ratio divided by a patient dose related parameter. An in house constructed phantom simulated a series of vessel segments with iodine concentrations from 10% or 30 mg/cc to 16% or 48 mg/cc of iodine in a blood plasma solution, all within the dimensional constraints of a paediatric patient. The phantom also used test inserts of tin (Sn). Measurements of Entrance Surface Air Kerma (ESAK) and exit dose rate were performed along with calculations of the signal-to-noise ratio (SNR) of all the objects. A first result showed that it was favourable to employ low dose fluoroscopy mode and lower frame rate modes in cine acquisition if dynamic information is not critical. Normal fluoroscopy dose mode provided a considerably higher dose level (in comparison to low dose mode) with only a slight improvement in SNR. Higher frame rate cine modes should be used however when the clinical situation dictates so. This work also found that tin should not be intended as iodine replacement material for research purposes due to the mismatching SNR, particularly on small vessel sizes.

Matched MeSH terms: Signal-To-Noise Ratio
Fulltext 56 nm Wide-Band Tunable Q-Switched Erbium Doped Fiber Laser with Tungsten Ditelluride (WTe2) Saturable Absorber

Ahmad H, Albaqawi HS, Yusoff N, Yi CW

Sci Rep, 2020 Jun 17;10(1):9860.
PMID: 32555280 DOI: 10.1038/s41598-020-66664-9

A wide-band and tunable Q-switched erbium-doped fiber (EDF) laser operating at 1560.5 nm with a tungsten ditelluride (WTe2) saturable absorber (SA) is demonstrated. The semi-metallic nature of WTe2 as well as its small band gap and excellent nonlinear optical properties make it an excellent SA material. The laser cavity uses an 89.5 cm long EDF, pumped by a 980 nm laser diode as the linear gain while the WTe2 based SA generates the pulsed output. The WTe2 based SA has a modulation depth, non-saturable loss and saturation intensity of about 21.4%, 78.6%, and 0.35 kW/cm2 respectively. Stable pulses with a maximum repetition rate of 55.56 kHz, narrowest pulse width of 1.77 µs and highest pulse energy of 18.09 nJ are obtained at the maximum pump power of 244.5 mW. A 56 nm tuning range is obtained in the laser cavity, and the output is observed having a signal to noise ratio (SNR) of 48.5 dB. The demonstrated laser has potential for use in a large number of photonics applications.

Matched MeSH terms: Signal-To-Noise Ratio

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