Secure Exchange of Digital Metrological Data in a Smart Overhead Crane.

Digitalization and the rapid development of IoT systems has posed challenges for metrology because it has been comparatively slow in adapting to the new demands. That is why the digital transformation of metrology has become a key research and development topic all over the world including the development of machine-readable formats for digital SI (D-SI) and digital calibration certificates (DCCs). In this paper, we present a method for using these digital formats for metrological data to enhance the trustworthiness of data and propose how to use digital signatures and distributed ledger technology (DLT) alongside DCCs and D-SI to ensure integrity, authenticity, and non-repudiation of measurement data and DCCs. The implementation of these technologies in industrial applications is demonstrated with a use case of data exchange in a smart overhead crane. The presented system was tested and validated in providing security against data tampering attacks.

Categorical scaling of partial loudness in a condition of masking release.

Categorical loudness scaling was used to measure suprathreshold release from masking. The signal was a 986-Hz sinusoid that was embedded in a bandpass-filtered masking noise. This noise was either unmodulated or was amplitude modulated with a square-wave modulator. The unmodulated noise had either the same level as the modulated noise or had a level that was reduced by the difference in thresholds for the 986-Hz signal obtained with the modulated and unmodulated noise masker presented at the same level (i.e., the masking release). A comparison with loudness matching data of the same set of subjects showed that the data obtained with loudness scaling capture main aspects of the change in suprathreshold perception of the sinusoid when the masker was modulated. The scaling data for the signal masked by the unmodulated noise with the reduced masker level were similar to that for the signal embedded in the modulated noise. This similarity supports the hypothesis that the mechanism eliciting the masking release is effectively reducing the masker level.

Relation between loudness in categorical units and loudness in phons and sones.

Data are presented on the relation between loudness measured in categorical units (CUs) using a standardized loudness scaling method (ISO 16832, 2006) and loudness expressed as the classical standardized measures phon and sone. Based on loudness scaling of narrowband noise signals by 31 normal-hearing subjects, sound pressure levels eliciting the same categorical loudness were derived for various center frequencies. The results were comparable to the standardized equal-loudness level contours. A comparison between the loudness function in CUs at 1000 Hz and the standardized loudness function in sones indicates a cubic relation between the two loudness measures.

Spectro-temporal weighting of loudness.

Real-world sounds like speech or traffic noise typically exhibit spectro-temporal variability because the energy in different spectral regions evolves differently as a sound unfolds in time. However, it is currently not well understood how the energy in different spectral and temporal portions contributes to loudness. This study investigated how listeners weight different temporal and spectral components of a sound when judging its overall loudness. Spectral weights were measured for the combination of three loudness-matched narrowband noises with different center frequencies. To measure temporal weights, 1,020-ms stimuli were presented, which randomly changed in level every 100 ms. Temporal weights were measured for each narrowband noise separately, and for a broadband noise containing the combination of the three noise bands. Finally, spectro-temporal weights were measured with stimuli where the level of the three narrowband noises randomly and independently changed every 100 ms. The data consistently showed that (i) the first 300 ms of the sounds had a greater influence on overall loudness perception than later temporal portions (primacy effect), and (ii) the lowest noise band contributed significantly more to overall loudness than the higher bands. The temporal weights did not differ between the three frequency bands. Notably, the spectral weights and temporal weights estimated from the conditions with only spectral or only temporal variability were very similar to the corresponding weights estimated in the spectro-temporal condition. The results indicate that the temporal and the spectral weighting of the loudness of a time-varying sound are independent processes. The spectral weights remain constant across time, and the temporal weights do not change across frequency. The results are discussed in the context of current loudness models.

Spectral loudness summation of nonsimultaneous tone pulses.

The level of broadband signals is usually lower than that of equally loud narrow-band signals. This effect, referred to as spectral loudness summation, is commonly measured for broadband signals where all frequency components are presented simultaneously. The present study investigated to what extent spectral loudness summation also occurs for nonsimultaneously presented frequency components. Spectral loudness summation was measured in normal-hearing listeners with an adaptive forced-choice procedure for sequences of short tone pulses with varying frequencies, randomly chosen from a set of five frequencies. In addition, spectral loudness summation was measured for the simultaneous presentation of all five frequencies. The comparison stimulus consisted of tone pulses with the same frequency for all tone pulses of the sequence and the same repetition rate and overall duration as the test signal. The pulse duration was 10, 20, 50, or 100 ms and the inter-pulse interval ranged from 0 to 390 ms. In general, a considerable nonsimultaneous spectral loudness summation was found for short pulse durations and inter-pulse intervals, but a residual effect was also observed for the largest inter-pulse interval. The data are discussed in the light of repetition-rate dependent spectral loudness summation and effects of persistence of specific loudness after tone-pulse offset.