A technique for in situ measurements of acoustic properties of a fibrous porous material is proposed in this paper. Proposed technique exploits a directivity pattern of a dipole source in its very near field. Theoretical analysis for the proposed technique is based on the Rayleigh integral with a complex reflection included. Results are compared with results of FEM analysis and show that flow resistivity of a porous material placed in the very near field of the dipole source has significant influence on the sound pressure at its ring. Results provide an excellent starting point for the design of the sensor for sound absorption.
COBISS.SI-ID: 13491995
Impulse noise is one of the most hazardous and annoying types of noise, which is present in the working and community environment. A-weighted equivalent sound pressure level, describing most types of noise, appears not to be the appropriate descriptor, especially not for high-impulsive and high-energy impulsive noise. However, this descriptor is often used as a basis for impulse noise evaluation, when combined with appropriate adjustment terms. But despite of objective character of such evaluation, care should be taken regarding certain facts, especially the source of impulse noise, its environment and time of measurement. In this article, the relationships between all these influential parameters have been investigated in detail. Today, on the other hand, a sophisticated sound level meter offers the possibility of simultaneous measurement of many acoustical descriptors. By combining some of these descriptors with some analytical investigations, as shown in this article, more useful information concerning impulse noise can be obtained. In this article some of them are used for more detailed analysis of impulse correction, according to some international standards.
COBISS.SI-ID: 13177627
The possibility of identifying vibration modes of a double bass bow, with a non-contact measurement of sound pressure in the Very Near Field (VNF) was investigated. This paper shows the application of this cost-effective method for vibroacoustic testings of the bow. The spectra of generated tones do not give sufficient information about a particular bow, but its vibroacoustical behavior provides additional properties. The visualization for all vibration modes below 4000 Hz was achieved by using sound pressure scanning in a VNF. Differences in the vibroacoustical properties of a double bass bow with different hair tension were analyzed.
COBISS.SI-ID: 13722139
A nationwide study was conducted to explore the short term association between daily individual meteorological parameters and the incidence of acute coronary syndrome (ACS) treated with coronary emergency catheter interventions in the Republic of Slovenia, a south-central European country. Method: We linked meteorological data with daily ACS incidence for the entire population of Slovenia, for the population over 65 years of age and for the population under 65 years of age. Data were collected daily for a period of 4 years from 1 January 2008 to 31 December 2011. In line with existing studies, we used a main effect generalized linear model with a log-link-function and a Poisson distribution of ACS. Results and Conclusions: Three of the studied meteorological factors (daily average temperature, atmospheric pressure and relative humidity) all have relevant and significant influences on ACS incidences for the entire population. However, the ACS incidence for the population over 65 is only affected by daily average temperature, while the ACS incidence for the population under 65 is affected by daily average pressure and humidity. In terms of ambient temperature, the overall findings of our study are in line with the findings of the majority of contemporary European studies, which also note a negative correlation. The results regarding atmospheric pressure and humidity are less in line, due to considerable variations in results. Additionally, the number of available European studies on atmospheric pressure and humidity is relatively low. The fourth studied variable—season—does not influence ACS incidence in a statistically significant way.
COBISS.SI-ID: 1536032195
In addition to direct effects on the auditory system, excessive noise also causes so-called nonauditory effects. These generally occur at lower sound pressure levels (SPL) and include changes in many organ systems and physiological processes. Review of recent literature shows that today non-auditory effects are quite well explained. In this article we list the most important sources of noise, their extent and extra-acoustic factors that modify the link between noise and its effects. We describe the pathophysiology, prevalence and significance of noise effects on hormonal status, immune functions, cardiovascular system, balance, visual functions, sleep quality, cognitive functions and behavior. We also summarize the conclusions of recent research on the impact of noise on the formation of acoustic neuroma and formation of connective tissue in the liver.
COBISS.SI-ID: 275409920