American National Standards Institute Research Articles

Impact of Skin Pigmentation on Pulse Oximetry Blood Oxygenation and Wearable Pulse Rate Accuracy: Systematic Review and Meta-Analysis.

Photoplethysmography (PPG) is a technology routinely used in clinical practice to assess blood oxygenation (SpO2) and pulse rate (PR). Skin pigmentation may influence accuracy, leading to health outcomes disparities. This systematic review and meta-analysis primarily aimed to evaluate the accuracy of PPG-derived SpO2 and PR by skin pigmentation. Secondarily, we aimed to evaluate statistical biases and the clinical relevance of PPG-derived SpO2 and PR according to skin pigmentation. We identified 23 pulse oximetry studies (n=59,684; 197,353 paired SpO2-arterial blood observations) and 4 wearable PR studies (n=176; 140,771 paired PPG-electrocardiography observations). We evaluated accuracy according to skin pigmentation group by comparing SpO2 accuracy root-mean-square values to the regulatory threshold of 3% and PR 95% limits of agreement values to +5 or -5 beats per minute (bpm), according to the standards of the American National Standards Institute, Association for the Advancement of Medical Instrumentation, and the International Electrotechnical Commission. We evaluated biases and clinical relevance using mean bias and 95% CI. For SpO2, accuracy root-mean-square values were 3.96%, 4.71%, and 4.15%, and pooled mean biases were 0.70% (95% CI 0.17%-1.22%), 0.27% (95% CI -0.64% to 1.19%), and 1.27% (95% CI 0.58%-1.95%) for light, medium, and dark pigmentation, respectively. For PR, 95% limits of agreement values were from -16.02 to 13.54, from -18.62 to 16.84, and from -33.69 to 32.54, and pooled mean biases were -1.24 (95% CI -5.31 to 2.83) bpm, -0.89 (95% CI -3.70 to 1.93) bpm, and -0.57 (95% CI -9.44 to 8.29) bpm for light, medium, and dark pigmentation, respectively. SpO2 and PR measurements may be inaccurate across all skin pigmentation groups, breaching U.S. Food and Drug Administration guidance and industry standard thresholds. Pulse oximeters significantly overestimate SpO2 for both light and dark skin pigmentation, but this overestimation may not be clinically relevant. PRs obtained from wearables exhibit no statistically or clinically significant bias based on skin pigmentation.

Transducer Variability in Speech-in-Noise Testing: Considerations Related to Stimulus Bandwidth.

Clinical audiologists typically assume that headphones and insert phones will produce comparable results when they are used to conduct speech-in-noise or other audiological tests; however, this may not always be the case. Here, we show that there are significant differences in the scores that previous studies have reported for headphone and insert-phone transducers on the Words-in-Noise (WIN) Test, and discuss the possibility that the variations in high-frequency output that are allowable under the speech source specifications of American National Standards Institute S3.6 might be contributing to transducer-dependent differences in performance for the WIN and other tests that are presented through the auxiliary input channels of clinical audiometers. A literature review was conducted to identify articles that reported WIN Test results for both listeners with normal hearing and with hearing impairment and specified the type of transducer (insert or TDH-50) used for the data collection. Among the 19 included studies, participants with normal hearing using inserts exhibited systematically worse WIN Test scores compared to those using TDH-50 headphones, while participants with hearing loss showed comparable average scores across transducer types. The results highlight the importance of considering transducer type when interpreting WIN Test outcomes, particularly when comparing to normative scores obtained from individuals with normal hearing. Although further research is needed to elucidate the underlying mechanisms driving differences in test performance across transducer types, these findings underscore the need for standardized test administration protocols and careful documentation of transducer type when administering speech-in-noise tests for clinical or research applications.

Mechanical Characterization of Sisal Fiber Reinforced PP Composite Panels

ABSTRACT This study investigates the mechanical properties of single and double-layer woven sisal mat-reinforced PP composite panels. Sisal fibers were extracted using the manual decortication method, resulting in fibers with a density of 1.43 g/cm3 and a diameter ranging from 0.4 mm to 0.6 mm. To improve the bonding between the sisal fibers and the matrix, the fibers were hand-spun into yarn and woven into mats. The study focuses on the unique material combination and the use of sisal as a natural fiber reinforcement. The 18 mm thick panels were tested for water absorption following ASTM D570, compression strength, and tensile strength following ASTM D3039 using the UTES-100 High Precision universal strength tester machine. Composite panels with single layers of 10% and 15% woven fabric mat, loaded with 8 kg and 10 kg, exhibited compressive strengths of 11.6KN and 12.5KN, respectively. Panels reinforced with two layers of 20% and 30% sisal woven fabric mat, loaded with 8 kg and 10 kg, had compression strengths of 12.2KN and 12.5KN, respectively. Moreover, composite samples with 15% single layer and 30% double-layer sisal woven fabric mat demonstrated a equal compression strength of 12.5KN, falling within the range recommended by ISO13006:2012. The tensile strength of 16.99MPa, although slightly below the recommended ISO13006 value of 20MPa for commercial-grade panels, indicates promising results. The study’s findings suggest that higher fiber content and additional reinforcement layers lead to increased compression and tensile strength. Furthermore, the moisture absorption rate of the developed composite panels was significantly lower than the 0.5% water absorption rate authorized by the American National Standard Institute.

Assessment of Δ9-THC and Δ9-THCCOOH bias, precision, and ionization suppression/enhancement between solid tissue homogenate and supernatant by LC-MS-MS.

Liquid chromatography-triple quadrupole mass spectrometry (LC-MS-MS) assays are frequently utilized for screening and confirmatory purposes in the forensic toxicology laboratory. While these techniques are excellent for the targeted identification and quantitation of a wide variety of drug classes, validation and determining fit-for-purpose is a significant requirement for each method. In the USA, the American National Standards Institute and Academy Standards Board first edition of Standard 036 currently serves as a primary resource in forensic toxicology method validation and mandates that laboratories evaluate critical performance characteristics to help ensure the production of forensically defensible results. Due to the variability of specimen quality frequently encountered in the discipline of postmortem toxicology, the State of Maryland Office of the Chief Medical Examiner Forensic Toxicology Laboratory routinely analyzes solid tissue specimens as part of the medicolegal death investigation process and evaluates liver as a representative solid tissue matrix during method validation. Authentic postmortem specimens (e.g. liver, kidney, skeletal muscle, and spleen) were used to investigate the effects of analyzing solid tissue homogenate versus solid tissue supernatant on bias, precision, and ionization suppression/enhancement of Δ9-THC and Δ9-THCCOOH. Bias was <20% for Δ9-THC and Δ9-THCCOOH in liver homogenate and supernatant with a single exception of the low QC concentration for Δ9-THC in liver homogenate (-29%). Within-run and between-run CV was <20% for Δ9-THC and Δ9-THCCOOH in liver homogenate and supernatant. Δ9-THC and Δ9-THC-d3 exhibited significant ion suppression in both liver homogenate and supernatant, while Δ9-THCCOOH and Δ9-THCCOOH-d3 showed both ion suppression and enhancement in these matrices. Noticeable quantitative differences were observed in authentic postmortem solid tissue homogenate and supernatant specimens despite evaluating identical tissue samplings. A brief discussion of the results is presented using a validated LC-MS-MS method for the confirmation and quantitation of Δ9-THC and Δ9-THCCOOH in postmortem casework.

Methods to Track Effective Doses from Airborne Radioactive Emissions for Compliance with 40 CFR 61, SUBPART H.

US Department of Energy national laboratories can play an integral role in not only the advancement of science but also in the treatment of various medical conditions through research and development activities conducted at radioisotope production facilities. A project has been underway at Oak Ridge National Laboratory since 2016 whose mission is to produce and supply the radioisotope 227Ac, which is used in a radiopharmaceutical developed to treat certain types of prostate cancer and bone metastases. Production activities result in the environmental release of airborne radioactive emissions, which are governed by Clean Air Act regulations described in 40 CFR Part 61, Subpart H. Stack 3039, the source that emits radioactive effluents from 227Ac production, is subject to additional requirements outlined in American National Standards Institute (ANSI) N13.1-1969 due to its grandfathered status. Radioactive emissions are limited to levels below those that would cause annual compliance dose standards for members of the public to be exceeded and stack 3039 to lose its grandfathered status. To allow for maximum production of 227Ac without exceeding relevant dose limits, monthly tracking of project emissions and resulting CAP88-PC modeled effective doses to a maximally exposed individual have been implemented. Four years of tracking data were compiled and analyzed to identify additional methods that could be used to estimate project doses more frequently, potentially further optimizing 227Ac production while maintaining compliance with applicable regulations.

Study on Fume Hood Improvements for Energy Savings and Minimum Face Velocity

A fume hood is a device that safely exhausts harmful substances generated during the experimental process to the outside, and for the safety of researchers and the protection of experimental samples, the balance between the amount of air flowing in and the speed at which it is discharged to the outside is extremely important. The Face velocity of the fume hood is recommended to be 0.5m/s (ASHRAE 110-2016) specified by the American National Standards Institute (ANSI). The Korea Occupational Safety and Health Corporation specifies 0.4 m/s (KOSHA-G-7-1999). To increase the functionality of the fume hood, it must be operated 24 hours a day while maintaining the prescribed Face velocity to make a safe laboratory environment. However, constantly powering them consumes a significant amount of electrical energy. Therefore, it's crucial to make efforts to reduce energy consumption. Some labs have adopted a method to minimize electrical usage by powering the hoods only when they're in use. In that case, it should be done with great caution. Because hazardous substances inside the hood could be leaked, putting the entire lab at risk. By implementing such measures, organizations and institutions managing lab facilities can effectively reduce energy consumption while ensuring the use of safe fume hoods. Additionally, there's a growing trend in research facilities to maintain Face velocity of fume hoods below 0.25 m/s as part of efforts to decrease and conserve electrical energy. This study stems from preliminary research aimed at achieving a stable face velocity in fume hoods. In this study, to reduce the face velocity of the fume hood, we changed the structural design of the fume hood based on existing research. As a result, the face velocity of the fume hood is reduced from 0.5 m/s to 0.297 m/s. the study reduced the face velocity to a maximum of 0.297m/s. To verify the performance of the fume hood with minimum face velocity, we tested the ventilation performance with the international standard test method. It proves that the fume hood with face velocity 0.297 m/s make no differences compared to existing fume hood with higher face velocity. In addition, the fume hood with minimum face velocity enables the reduction of energy consumption.

A Comprehensive Study on Safety and Working Gloves Used in Indian Aviation

This study aims to learn about Indian aviation’s safety norms, the world’s fastest-growing aviation market. In this, we will understand the different types of safety measures regarding safety and working gloves implemented by DGCA, Operators of Civil Aviation and Governing bodies of Defence Aviation during the operation, servicing and rectifying aircraft and its subsidiary systems. The author explains the current methods and conditions technicians and operators adopt regarding gloves. We will understand and analyse the advantages and limitations of these guidelines circulated by the Aircraft Maintenance Manual (AMM) and Governing agencies. We are studying different standards as per European Committee for Standardization (CEN), American National Standards Institute (ANSI), International Electrotechnical Commission (IEC) and the Bureau of Indian Standards (BIS) and cross-compare them with each other and understanding their pictograms. The author tries to compare these requirements in the aviation field and implement them in every guideline of aviation governing bodies regarding safety/working gloves used in aircraft maintenance and operations.

Saturated phase change threshold of plume flow gas species under low temperature and rarefied environment

Gas species in high altitude plume flow are all exposed to low temperature, thus making possible phase change processes on those other than H2O vapor. In order to obtain saturated threshold of gas species, which is normally abundant in plume flow, this study establishes Gibbs phase calculation method for CO2, CO, H2, and N2. The non-continuum effect caused by rarefied gas environment is quantitatively calculated by ratio between molecular free path scale and characteristic length of investigated object. Validation on Gibbs method is guaranteed by comparison between calculated results and data from American National Standards Institute (ANSI), while non-continuum effect method is verified by revealing essential reason for gas-solid phase change processes resembling droplet condensation phenomenon observed in high altitude environment. According to the results, non-continuum effect only influences gas-solid boundary. Phase change for rarefied gas species can only occur under low temperature. Saturated threshold deflects toward solid phase region below specific molecules number density, thus decreasing gas to solid phase change trend. Both increasing on characteristic length and existence of other gas components contamination decreases non-continuum effect. Variation on non-continuum effect shows biggest influence on CO2 saturated phase change threshold, while shows smallest influence on that of N2.

Comparing alcohol involvement among injured pedalcycle and motorcycle riders across three national public-use datasets

Background Annually since 2008; over 38% of fatally injured motorcycle riders and 20% of pedalcyclists involved in traffic crashes were under the influence of alcohol, yet public health surveillance of alcohol involvement in these injuries is underdeveloped. This study determined alcohol involvement among fatally and non-fatally injured pedalcycle and motorcycle riders and compared findings across three national public-use datasets. Methods Using the 2019 National Emergency Medical Services Information System (NEMSIS), the Fatality Analysis Reporting System (FARS), and National Electronic Injury Surveillance System (NEISS) datasets, we identified alcohol involvement in fatal and non-fatal injuries to pedalcycle and motorcycle riders (≥21 years). Alcohol involvement was positive based on the clinician’s evaluation of alcohol at the scene (NEMSIS) or within the ED record (NEISS); or when Blood Alcohol Content (BAC) values were ≥.01 (FARS). Pedalcycle and motorcycle injuries were identified across datasets using: 1) ICD10 codes for pedalcycle (V10-V19) or motorcycle (V20-V29) within the cause of injury and EMS respondent’s impression of the encounter variables (NEMSIS); 2) product codes for bicycles or moped/power-assisted cycle/minibike/two-wheeled, powered, off-road vehicles (NEISS); and 3) American National Standard Institute’s classifications for pedalcycle and motorcycle in the person and vehicle type variables (FARS). The descriptive epidemiology was compared across datasets. Results There were 26,295 pedalcyclist and 50,122 motorcycle rider injuries resulting in an EMS response within NEMSIS data; 10.2% and 8.5% of these injuries respectively involved alcohol. These estimates were greater than the 7.3% of pedalcyclist and 6.1% of moped/power-assisted cycle/minibike/two-wheeled, powered, off-road vehicle injuries involving alcohol among patients who presented to an ED within the NEISS dataset. Based on FARS data, alcohol was involved in 27.0% of pedalcyclist and 42.0% of motorcyclist fatal injuries. Regardless of the data source, pedalcyclist and motorcycle fatal and non-fatal injuries were more likely to involve alcohol among middle-aged adults compared to older and early aged adults, and for men compared to women, with proportions that were generally 3-8% higher for men. Conclusions Measures for pedalcycle and motorcycle injuries and alcohol involvement vary substantially across national public-use datasets. Standardized, valid, and feasible methods are needed to accurately inform injury prevention efforts.

Coupling Gold Nanospheres into Nanochain Constructs for High-Contrast, Longitudinal Photoacoustic Imaging.

Structural parameters play a crucial role in determining the electromagnetic and thermal responses of gold nanoconstructs (GNCs) at near-infrared (NIR) wavelengths. Therefore, developing GNCs for reliable, high-contrast photoacoustic imaging has been focused on adjusting structural parameters to achieve robust NIR light absorption with photostability. In this study, we introduce an efficient photoacoustic imaging contrast agent: gold sphere chains (GSCs) consisting of plasmonically coupled gold nanospheres. The chain geometry results in enhanced photoacoustic signal generation originating from outstanding photothermal characteristics compared to traditional gold contrast agents, such as gold nanorods. Furthermore, the GSCs produce consistent photoacoustic signals at laser fluences within the limits set by the American National Standards Institute. The exceptional photoacoustic response of GSCs allows for high-contrast photoacoustic imaging over multiple imaging sessions. Finally, we demonstrate the utility of our GSCs for molecular photoacoustic cancer imaging, both in vitro and in vivo, through the integration of a tumor-targeting moiety.

Chapter 2: My Hearing Aid Isn't Working Like It Used to…

AbstractThis chapter will take you through specific patient complaints and the test box measures you can use to address these complaints. These measurements give you data that aid in your decision making about what is wrong, if anything, with the hearing aid and how you might address the problem. Before we discuss specific patient complaints and problems, let us review the American National Standard Institute (ANSI) guidelines for hearing aid testing in a test box.

Comparison of two acoustic test fixtures for measuring impulse level dependent attenuation

In the American National Standards Institute (ANSI) S12.42-2010 standard for measuring insertion loss of hearing protection devices (HPDs) in impulsive noise, the range of peak sound pressure levels for the impulses is 132 to 168 dB peak sound pressure level (dB pSPL). The specification of the acoustic test fixtures (ATFs) included an IEC 60318-4 ear simulator fitted with a microphone. The microphones typically used are a ¼” cartridge and have a dynamic range up to about 169 dB pSPL. For most small caliber firearms, the peak SPLs are less than 170 dB SPL at the location of the shooters ear (Schulz et al. 2013). For some military weapon systems that produce impulses greater than 170 dB pSPL, impulse insertion loss cannot be assessed without exceeding the microphone maximum dynamic range. Some condenser microphones have maximum dynamic ranges of 190 dB pSPL. This paper compares insertion losses for HPDs measured on two GRAS 45CB ATFs with microphones with maximum dynamic ranges of 169 and 193 dB pSPL. Waveform distortion, field probe to unoccluded transfer functions between the ATF and field probe will be examined for distortion and accuracy when estimating the impulse level dependent attenuation.

Navigating the bioacoustic landscape: Standardization and interoperability of acoustic data products

The importance of bioacoustics for understanding and protecting the natural world has grown significantly over the last few decades. Our capacity to monitor the acoustical landscape has increased with lower cost instrumentation, improved communication, infrastructure, and storage, as well as the development of reliable machine learning methods for analysis. Understanding long-term trends in animal populations as well as the impacts of anthropogenic noise requires the ability to retain and interpret records over decadal time scales, record in detail what type of analysis has been performed and understand when multiple analyses may be combined and when they should not be. This is not possible without a well-defined set of terms and meanings. In this talk, we will provide an overview of the work of Acoustical Society of America’s working group S3-SC1-WG7 that has been charged with developing an American National Standards Institute standard for bioacoustics information derived from acoustic recordings. The proposed standard details what information should be recorded for bioacoustics recording and analysis effort, ranging from specification of data to be noted about instrumentation to information gleaned from recordings such as noise levels, animal calls, and acoustic source locations.

Spectral Dependence of Light Exposure on Retinal Pigment Epithelium Disruption in Living Primate Retina.

RPE disruption with light exposures below or close to the American National Standards Institute (ANSI) photochemical maximum permissible exposure (MPE) have been observed, but these findings were limited to two wavelengths. We have extended the measurements across the visible spectrum. Retinal imaging with fluorescence adaptive optics scanning light ophthalmoscopy (FAOSLO) was used to provide an in vivo measure of RPE disruption at a cellular level. The threshold retinal radiant exposures (RREs) for RPE disruption (localized detectable change in the fluorescence image) were determined at 460, 476, 488, 530, 543, 561, 594, 632, and 671nm (uniform 0.5° square exposure) using multiples locations in 4 macaques. FAOSLO is sensitive in detecting RPE disruption. The visible light action spectrum dependence for RPE disruption with continuous wave (CW) extended field exposures was determined. It has a shallower slope than the current ANSI blue-light hazard MPE. At all wavelengths beyond 530nm, the disruption threshold is below the ANSI blue-light hazard MPE. There is reciprocity of exposure irradiance and duration for exposures at 460 and 594nm. We measured with FAOSLO the action spectrum dependence for photochemical RPE disruption across the visible light spectrum. Using this in vivo measure of phototoxicity provided by FAOSLO, we find that thresholds are lower than previously measured. The wavelength dependence in our data is considerably shallower than the spectral dependence of the traditional ANSI blue-light hazard, emphasizing the need for more caution with increasing wavelength than expected.

Costs involved in compliance with new endoscope reprocessing guidelines.

In March 2022, the Association for the Advancement of Medical Instrumentation (AAMI) released the American National Standards Institute (ANSI)/AAMI ST91:2021, their latest update on comprehensive, flexible, and semirigid endoscope reprocessing. These updated standards recommend the sterilization of high-risk endoscopes when possible and provide new recommendations for the precleaning, leak testing, manual cleaning, visual inspection, automated reprocessing, drying, storage, and transport of endoscopes. ANSI/AAMI ST91:2021 was compared with ANSI/AAMI ST91:2015 for major reprocessing differences that result in either time and/or cost increases. Time estimates were captured by explicit recommendation inclusion or taken from the literature. All the costs were estimated using publicly available resources. The updated standards represent a potential 24.3-minute and 52.35 to 67.57 United States dollars increase per procedure in terms of reprocessing time and spending, respectively, not including capital investments. Capital costs per procedure were highly dependent on the procedure volume of the facility. The new AAMI standards recommend several major changes, such as sterilization, for facilities to reprocess and manage endoscopes between uses. As more facilities increase their reprocessing methods to reflect the updated standards, they do so at a cost and introduce several delays. As the reprocessing landscape evolves, facilities should consider their true costs and alternative solutions, such as single-use endoscopes.

Solubilidade e pH dos cimentos forradores de hidróxido de cálcio

ABSTRACT Objective: To analyze the solubility and the potential of hydrogen ions in calcium hydroxide-based lining cements used in dentistry to protect the dentin-pulp complex during rehabilitation treatments. Methods: The evaluated cements bear the commercial names Dycal (Dentsply Sirona), Hydcal (Maquira), Hydro C (Dentsply Sirona), and light-cured Biocal (Biodinâmica). Solubility measurements followed the methodologies proposed by the American National Standards Institute and the American Dental Association, while the potential of hydrogen was determined using a digital pH meter. Results: Solubility exhibited no significant differences either individually or between the groups. Regarding the potential of hydrogen, the results were as follows: Dycal 12.06, Hydcal 12.06, Hydro C 10.5, and light-cured Biocal 8.48, highlighting disparities between the groups. Conclusion: There were no statistically significant differences in the descriptive analysis of the solubility of the tested calcium hydroxide cements. However, the descriptive analysis of the pH of the cements revealed statistically significant variances between the groups.

A Microfluidic High-Capacity Screening Platform for Neurological Disorders.

Compartmentalized cell cultures (CCCs) provide the possibility to study mechanisms of neurodegenerative diseases, such as spreading of misfolded proteins in Alzheimer's or Parkinson's disease or functional changes in, e.g., chronic pain, in vitro. However, many CCC devices do not provide the necessary capacity for identifying novel mechanisms, targets, or drugs in a drug discovery context. Here, we present a high-capacity cell culture microtiter microfluidic plate compliant with American National Standard Institute of the Society for Laboratory Automation and Screening (ANSI/SLAS) standards that allows to parallelize up to 96 CCCs/experimental units, where each experimental unit comprises three microchannel-connected compartments. The plate design allows the specific treatment of cells in individual compartments through the application of a fluidic barrier. Moreover, the compatibility of the plate with neuronal cultures was confirmed with rodent primary as well as human-induced pluripotent stem cell-derived neurons of the central or peripheral nervous system for up to 14 days in culture. Using immunocytochemistry, we demonstrated that the plate design restricts neuronal soma to individual compartments, while axons, but not dendrites, can grow through the connecting microchannels to neighboring compartments. In addition, we show that neurons are spontaneously active and, as deemed by the appearance of synchronous depolarizations in neighboring compartments, are synaptically coupled. In summary, the design of the microfluidic plate allows for both morphological and functional studies of neurological in vitro cultures with increased capacity to support identification of novel mechanisms, targets, or drugs.

Öğrenme Ortamlarının Mevcut İmkanlarından Faydalanılarak Akustik Ortamların Oluşturulması ve Karşılaştırılması

In this study, the situation that noise in schools has a significant effect on students' adaptation and understanding of the lesson was discussed. In classroom environments where students gain academic, social and emotional skills, 60.00-75.00% of learning activities require verbal communication with the teacher and other students (American National Standards Institute [ANSI], 2002; The Institute for Enhanced Classroom Hearing [IECH], 2018). In this context, the process was carried out in order to consider the acoustic quality of the educational environment as one of the important elements that determine the quality of the learning and teaching process. In this research, the effect of the acoustic arrangement of the classrooms as a learning environment on the listening and perception activities of the students was examined. For this reason, the main purpose of this research, the acoustic arrangements, without any professional support, alternatively, with the help of the students' bags or with acoustic diffusers that they can make themselves (for example, plastic bottles) are based on the situation of making the learning environment more efficient acoustically. The research design is the experimental design. The experimental process was carried out in the classroom environment of Maltepe Kadir Has Science and Art Center. The classroom and students in which the audio recordings were made were randomly assigned. Measurements were made by lecturing in an environment where acoustic study was not done and where it was done. The listening and perception activities of the students in the classroom in line with the acoustic studies were examined with the help of a semi-structured interview form. In this direction, it has been determined that an acoustic environment can be created with simple materials and that the acoustic environment affects student listening and perception activity. Keywords: Acoustics, Listening, Perception, Learning Environments

Professional Standards in Questioned Documents Expertises

Criminalistic/forensic expert examination of documents is a segment of criminal technique, i.e. forensic science. In modern countries, these activities are undertaken by highly specialized services that are frequently under the control of various security structures (judiciary, police, immigration services, etc.). In Bosnia and Herzegovina (as well as in the countries of the former Yugoslavia), these jobs have traditionally been associated with police agencies whose actions fall into the sphere of criminal techniques (more recently, forensics). Certain methods of behaving, ways of functioning, as well as processes linked to staff training and ways of acting within individual activities of this sort of expertise, have been formed via the accomplishment of the aforementioned duties. The purpose of this article is to introduce the field of criminal expert examination of questioned documents, namely the knowledge and conditions that a welltrained expert in this field should have. Furthermore, the work demonstrates in greater detail how the necessary insights and knowledge should be gathered. The fundamental reason for this work´s theme is the goal to describe this field from the standpoint of modern science, profession, and established standards that are used around the world. Another motive is the goal to explain the settings of this sector in a scientific and practical manner from the standpoint of international experience. Specifically, the article will examine some of the international standards and procedures for this field of expertise. The preceding study will be based on a survey of comparative literature as well as an examination of the standards and practices of organizations such as: The Scientific Working Group for Forensic Document Examination (SWGDOC), American Board of Forensic Document Examiners (ABFDE), American Academy of Forensic Sciences (AAFS), American National Standards Institute (ANSI), The American Society of Questioned Document Examiners (ASQDE), Southwestern Association of Forensic Document Examiners (SWAFDE), Southeastern Association of Forensic Document Examiners (SAFDE) and The European Network of Forensic Science Institutes (ENFSI).

On the test method for short-term level fluctuation of sound calibrators

Most noise bylaws state that a precision sound level meter which meets the International Electrotechnical Commission Publication 651 or the American National Standards Institute S1.4-1983 needs to be used for noise measurements. To ensure measurement accuracy, sound calibrators are used to check the sound level meter accuracy before and after any such measurements, as required by most noise regulations. The sound calibrator itself needs to be calibrated routinely and traceable to national standards. The International Standard IEC 60942, Electroacoustics - Sound calibrators, specifies performance requirements for the sound pressure level, short-term level fluctuation, frequency, and distortion and associated test methods. However, the test method for short-term level fluctuation specified in IEC 60942 is problematic. The short-term level fluctuation cannot be measured in some cases using the method specified in IEC 60942. In this paper, a detailed theoretical analysis is presented addressing this particular issue. Closed-form solutions are obtained for typical sinusoidal sound signals. Two experimental setups and measurement results for the validation of the theoretical analysis are also presented. One uses a commercial sound level meter and the other uses a precision sound pressure measurement system developed recently at the National Research Council Canada.