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Scientific news from division 1

The volume of silicon spheres with a mass of 1 kg could previously be measured by means of hydrostatic weighing with an uncertainty of 0.8 mm³ (k = 2). Using new and more stable thermistors to determine the temperature distribution in the measuring liquid of the fundamental weighing apparatus, a hydrostatic volume determination with an uncertainty of 0.35 mm³ (k = 2) will be possible in the...

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For the first time, torque measurement in nacelle test benches has been traced to the national standard. Common torque calibration standards only provide methods for static torque calibration. However, for torque measurement in nacelle test benches, calibration at varying rotational speeds is required. The findings and research will contribute to a reliable efficiency determination.

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For the recently developed circumaural audiometric RadioEar DD65v2 headphone, reference hearing thresholds were determined for pure-tone audiometry and free-field equalization data for use in speech audiometry. For this purpose, a series of standardized auditory tests were conducted on 25 test subjects who had normal hearing. The reference data for calibrating audiometers equipped with this...

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Within the scope of comparison measurements with regard to the results of the determination of the Avogadro constant and the Planck constant with the aid of the first two monocrystalline silicon spheres AVO28-S5c and AVO28-S8c [1] made of highly enriched silicon (degree of enrichment for 28Si: > 99.99 %), also the mass of the spheres in vacuum was determined again.

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The quality of life experienced in rooms depends significantly on their acoustic properties. Acoustics has to fit the purpose of the room. Meeting rooms must enable the comprehension of spoken language, open-plan offices undisturbed work. Measures for appropriate room acoustics need the sound absorption of room surfaces and interior objects as a main input quantity.

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A procedure to measure airborne ultrasound is being developed within the scope of Ears II, an EU research project. This procedure, which is designed for occupational safety, has been developed to reliably determine the exposure of staff to airborne ultrasound at the workplace. Important findings obtained during its development were provided by sound field scans with a high spatial resolution at a...

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