Study on audiometer calibration at the extended high-frequency range 8–16 kHz

Audiometry is a branch of acoustical measurements that concentrated on testing the devices related to hearing and used in medical part such as audiometer. It is substantial to calibrate the audiometer to assure the measurement traceability and to safe human health. So, it is considered as a major claim. The importance of calibration comes from the request for advanced instrument to test accurately the hearing loss for human, especially for those people who might be at risk due to noise. The conventional audiometry covered from 125 to 8 kHz, while the extended high-frequency (EHF) audiometry above 8 up to 20 kHz, the last-mentioned type may be useful in early diagnosis of hearing loss. The audiometer calibration performed using ear simulator, standard or working microphone, sound level meter, and frequency analyzer according to IEC60645-1. The physical parameters such as sound pressure level, frequency and distortion may be affected by environmental conditions such as temperature change. The gained results observed that the measured value of all the tests performed was affected by temperature variation. There were deviations observed from each performed test’s nominal values in the calibration process as the temperature varies from 16 to 40°C. So, this is a detailed study for the significance, method, and uncertainty estimation for audiometer calibration covering the EHF ranges within the temperature from 16 to 40°C.

Overview of legal traceability of GPS positioning in Australia

Global Positioning System (GPS) position verification and legal traceability in Australia supports industry, trade, science and innovation and is trusted and recognized domestically and internationally. At the end of 2017, the Australia’s national datum was transitioned from the Geocentric Datum of Australia 1994 (GDA94) to the Geocentric Datum of Australia 2020 (GDA2020). As such, the datum for the legal traceability of GPS positions in Australia has also moved to GDA2020. This paper highlights the importance of legal metrology and measurement in terms of GPS positions in accordance with the National Measurement Act 1960 (Commonwealth of Australia). Here we provide an overview of the process of issuing the so-called ‘Regulation 13 Certificates’ for Continuously Operating Reference Stations (CORS) across Australia. The position verification methodology is detailed, including the quality control, metadata assurance, and dynamic management of the certificates as well as positional uncertainty determination of CORS with varying quality. A quality monitoring system of positions is also discussed along with how measurement traceability is ensured including short-term and long-term position monitoring schemes.

Lean and metrology: a systematic review and bibliometric analysis of the scientific literature from the last 20 years

The metrology area is responsible for measurement properties and is present in the market through services related to calibration, standardization, maintenance, measurement traceability, and certification. While there is a demand from metrology companies for efficient methods of managing the quality of their services and operations, lean culture encompasses the most important management techniques with applications in various segments. Considering the aspects that permeate these two areas, the question arises about a possible intersection between the demands of companies and metrology laboratories to remain competitive and certified in the market and benefits provided by lean culture. Thus, this paper performs a systematic review, according to the PRISMA protocol, in order to verify if there is an intersection between lean and metrology in the scientific literature. Through bibliometric and qualitative analyses, the research shows a gap of application with a lack of articles in this area, as well as a great potential of places and tools to be implemented.

Case study for sampling effect in nanometric surface roughness of ultra-precision grinding

Nanometric surface roughness (NSR) is commonly produced in ultra-precision grinding (UPG). However, the NSR would be significantly affected by the sampling frequency (SF), i.e. sampling effect, since it is governed by rich low, middle, and high spatial frequency features. Hereby, the case study focused on discussing sampling effect in the NSR of UPG. The theoretical and experimental results have been found that along with the SF increase the NSR rises and rapidly converges and the SF is over 10 times of the spatial frequency for the NSR within the 5% distortion. Moreover, the NSR is acceptable within its 5% variation ratio under two SFs. Further, the SFs should be provided as the measurement traceability, together. Significantly, the case study draws up a better insight into sampling effect in the NSR of UPG along with a feasible suggestion on its measurement.