The pandemic of COVID-19 and the resulting countermeasures have made it difficult or impossible to perform listening tests in controlled laboratory environments. This paper examines the possibility of using speech for level calibration of sound reproduction systems used in listening tests performed in non-laboratory conditions, i.e., when such tests are distributed through the means of electronic communication and performed in a home environment. Moreover, a larger pool of potential test subjects can be reached in this manner. The perception of what the “normal” level of reproduced speech should be was examined through a listening experiment by letting the listeners set the level of reproduced speech samples as they saw fit, depending on the used sound reproduction system, the (non)existence of visual stimulus, and the voice of the speaker. The results show that the perception of normal speech level is highly individual when it comes to setting that level by listening to reproduced speech. The interindividual differences between the subjects are considerably larger than the impact of the three main effects. The understanding of what the “normal” level of read speech should be was examined experimentally as well by asking the subjects to read a paragraph of text, depending on the visual stimulus. The results show that the “normal” level of read speech is reasonably consistent and averages at 55 dBA at a normal conversational distance of 1 m, in a room with room acoustics conditions typical for home environment and low background noise, and with the visual stimulus that mimics the interlocutor put within the personal space of the reader. A preliminary proposal is given of a level calibration method for non-laboratory listening experiments based on these results, and some of its aspects that require further research are discussed.

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CCQM-K124 was organized by the Inorganic Analysis Working Group (IAWG) of CCQM to assess and document the capabilities of the national metrology institutes (NMIs) or the designated institutes (DIs) to measure the mass fractions of trace elements (As, B, Cd, Ca, Cr, Hg and Mo) and hexavalent chromium (Cr(VI)) in drinking water. The National Metrology Institute of Japan (NMIJ) and the Government Laboratory, Hong Kong SAR (GLHK) acted as the coordinating laboratories. This comparison is divided into two parts. Part A was organized by the NMIJ and the trace elements were the analytes, and Part B was organised by the GLHK and Cr(VI) was the analyte. In Part A, results were submitted by 14 NMIs and nine DIs. The participants used different measurement methods, though most of them used direct measurement using inductively coupled plasma-optical emission spectrometry (ICP-OES), inductively coupled plasma-mass spectrometry (ICP-MS), and isotope dilution technique with ICP-MS. The results of As, B, Cd, Ca and Cr show good agreement with the exception of some outliers. Concerning Hg, instability was observed when the sample was stored in the light. And some participants observed instability of Mo. Therefore, it was agreed to abandon the Hg and Mo analysis as this sample was not satisfactory for KC. In Part B, results were submitted by six NMIs and one DI. The methods applied were direct measurement using 1,5-diphenylcarbazide (DPC) derivatisation UV-visible spectrophotometry, standard addition using ion chromatography-UV-visible spectrophotometry or HPLC—inductively coupled plasma-mass spectrometry (ICP-MS) and isotope dilution technique with ion chromatography—ICP-MS. The results of all participants show good agreement. Accounting for relative expanded uncertainty, comparability of measurement results for each of As, B, Cd, Ca, Cr and Cr(VI) was successfully demonstrated by the participating NMIs or DIs. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

The use of audio systems that employ binaural synthesis with head tracking has become increasingly popular, particularly in virtual reality gaming systems. The binaural synthesis process uses the Head-Related Transfer Functions (HRTF) as an input required to assign the directions of arrival to sounds coming from virtual sound sources in the created virtual environments. Generic HRTFs are often used for this purpose to accommodate all potential listeners. The hypothesis of the research is that the use of individual HRTF in binaural synthesis instead of generic HRTF leads to improved accuracy and quality of virtual sound source localization, thus enhancing the user experience. A novel methodology is proposed that involves the use of dynamic virtual sound sources. In the experiments, the test participants were asked to determine the direction of a dynamic virtual sound source in both the horizontal and vertical planes using both generic and individual HRTFs. The gathered data are statistically analyzed, and the accuracy of localization is assessed with respect to the type of HRTF used. The individual HRTFs of the test participants are measured using a novel and efficient method that is accessible to a broad range of users.

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