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17.06 Information Technology Noise

Round-robin testing on Sound power level measurement for Reference Sound Source and Office printer
Time: 6:00 am

Author: Kohei Shimoda

Abstract ID: 1698

Round-robin testing for two samples, Reference Sound Source in accordance with ISO 6926 and Office printer with electrophotographic engine, were executed by seven testing laboratories in Japan on 2020. All tests were executed with parallelepiped measurement surface in hemi anechoic chamber in accordance with testing standard for engineering-grade sound power determination, ISO 3744:2010. The results show that sample standard deviation for RSS is better than printer. Standard deviations for overall A-weighted sound power level for two samples are better than combined standard uncertainties calculated with reference example of standard deviations in ISO 3744 (1.5 dB for Reference Sound Source as standard deviation of operating/mounting condition is negligibly small, 1.6 dB for printer as stable operating/mounting condition 0.5 dB). This paper also indicates tips for those who would conduct round-robin testing to obtain valid results by obviating incorrect operations and malfunctions of printers or similar equipment from the experience of some round-robin tests.

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Statistical assessment of A-weighted sound power level for printer with electrophotographic engine
Time: 6:20 am

Author: Kohei Shimoda

Abstract ID: 1700

Statistical distribution and statistical upper limit (the value which 93.5 % of the batch of new equipment are expected to lie) of A-weighted sound power level for one office printer were experimentally estimated from 10 new samples picked up from market. The printer is capable of A4-size printing with electrophotographic engine which corresponds Annex C.16 Page printers in ECMA?74 17th (2019). A-weighted sound power level for continuous printing mode was determined in accordance with noise test code for ITTE (Information Technology and Telecommunications Equipment such as printers and personal computers), ISO 7779:2018 and ECMA-74 Annex C. Sample standard distribution of production of overall A-weighted sound power level (determined from 100-10000 Hz one-third-octave band) is 0.25 dB, whereas individual one-third-octave band has larger distribution. The value obtained is better than reference distribution 1.32 dB set in ISO 9296:2017 which states estimation of statistical upper limit value of the batch of equipment for ITTE.

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Head related transfer function measurements of common PPE
Time: 8:20 pm

Author: Megan Ewers

Abstract ID: 2134

Due to COVID 19, personal protective equipment (PPE) is now used in everyday life. Such PPE affects communication and perception. This paper provides an overview of the impact of PPE on Head Related Transfer Functions (HRTF’s). Spatial acoustic effects of common PPE on human hearing can be documented to improve and inform field worker safety and communication. After a general description of the measurement process and required tools, we focus on a few methods which contribute significantly to the accuracy and analysis of PPE-based HRTF data. The dedicated setup allows measuring a full 360 degree map in automated fashion. It includes a special ring setup with 25 speakers, and a precise turn table that is used to adjust the angle of the device under test with respect to the ring. Binaural measurements were performed on a set of common PPE items on a Head And Torso Simulator (HATS) system, including hard hats, safety glasses, hearing protection, and various face masks. An overview of the data is presented.

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High-resolution spectral analysis (HSA) vs. discrete fourier transform (DFT)
Time: 7:00 am

Author: Roland Sottek

Abstract ID: 2172

The Discrete Fourier Transform (DFT) is the standard technique for performing spectral analysis. It is used in the form of the well-known fast implementation (FFT) in almost all areas that deal with signal processing. However, the DFT algorithm has some limitations in terms of its resolution in time and frequency: the higher the time resolution, the lower the frequency resolution, and vice versa. The product of time (analysis duration) and analysis bandwidth (frequency resolution) is a constant. DFT results depend on the analysis window used (type and duration), although the physical signal properties do not change. The High-Resolution Spectral Analysis (HSA) method, published at the ASST ‘90, considers the window influence through spectral deconvolution and thus leads to a much lower time-bandwidth product, correlating better with human perception. Recently, variants of the HSA have been used for a psychoacoustic standard (roughness). Additionally, HSA is planned for a new model of fluctuation strength. This paper describes the improvements made to the HSA algorithm as well as its robustness against noise, and compares application results for both methods: HSA and DFT.

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Application of psychoacoustic analyses according to ECMA-418-2
Time: 6:40 am

Author: Julian Becker

Abstract ID: 2174

Assessing and assuring sound quality has become a very important task for product design. Customers expect product sounds without disturbing noises. This is a challenge because spectro-temporal noise patterns (such as tonal sounds or modulated signals that generate a roughness sensation) must be taken into account, in addition to frequency-weighted values like dB(A) and loudness. If the sound of a technical product exhibits these characteristics, it is most likely perceived as having poor quality. The new standard ECMA-418-2 describes methods for the automatic quantification of tonal sounds and modulated sounds, which generate a sensation of roughness. The methods are based on a psychoacoustic hearing model and thus emulate human perception very closely. This paper describes the application of these methods. Several examples show how these parameters can be used for sound engineering and how to interpret the results.

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New ECMA 74 operating conditions for personal computers and workstations
Time: 7:20 am

Author: Willem Beltman

Abstract ID: 2921

Annex C in ECMA 74 outlines the operating conditions for personal computers and workstations during acoustic testing. In practice, the way systems are used and designed changes over time. After InterNoise 2018 in Chicago, a special IT industry workgroup was formed with the goal to update this section in Annex C to better reflect current workloads during use. This paper outlines the new operating conditions that were developed by this workgroup. It describes the different operating modes to be measured, and how to set and document power and performance parameters during the acoustic measurements. In addition to the standard idle condition, it includes operating conditions selected from the following usage scenarios: 1) web browsing, 2) office productivity, 3) media content creation, and 4) power user/gaming.

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