MEASUREMENT OF THE EFFECT ON VIOLINS OF AGEING AND PLAYING
This is a report on the first three years of a long-term experiment designed to measure how two very similar violins change with time. After being constructed ‘in parallel,’ one is stored under controlled conditions in a museum and is played infrequently, while the other is played regularly by a professional musician. Vibro-acoustic measurements were performed on the instruments and parts thereof during and after construction. Playing and listening tests by a panel of experienced violinists were conducted at completion, after three years with no adjustment, and then after minor adjustments were made to the played violin only. Panels of players and listeners rated the two violins at all stages, and all results are consistent with the null hypothesis: at present there is no significant preference for either instrument over a range of categories.
Wavelets in elimination of distortions in the recorded violin sound
The topic of the article is a continuation of the works about violin sound recognition. This paper shows how to achieve higher quality of recorded sound, which is closer to human's subjective perception, using signal processing and algorithms, which consider using violin playing techniques and behavior of the violinist. The filter, which provides the best result as well as perception and data analysis spectrum is a one-shot filter based on wavelet transform, with experimentally designated universal wavelet form for each technique. The work also delivers such information as safety and optimization way of processing audio parameters in the production code.
FORTE observations of lightning radio‐frequency signatures: Capabilities and basic results
The FORTE satellite, launched on August 29, 1997, carries both radio‐frequency‐receiver and optical (imaging and photometric) payloads for the study of lightning. The radio‐frequency (RF) data for the first 7 months of operation are described, both to illustrate the satellite's capabilities and to explain the basic statistical findings so far. FORTE's multichannel RF trigger system represents a significant advance in space‐based monitoring of lightning emissions. We are able to observe even rather weak and diffuse RF emissions from lightning and are no longer limited to the brightest known events, “transionospheric pulse pairs,” or TIPPs. We do see TIPPs, and we show that the FORTE observations of TIPPs are consistent only with the second pulse's being due to a ground reflection. We find that TIPPs are basically bimodal in character, one type having a steep roll‐off of power from 38 to 130 MHz and the other being essentially flat‐spectrum in that range. The steep‐spectrum TIPPs cluster together in the manner of most RF emissions from lightning, while the flat‐spectrum events tend to maintain a wider spacing (>0.1 s) between recurrent emissions.