An optimisation approach to the location and sizing of multiple leaks in a duct

A single leak in a duct can be located, and its size predicted, by measuring the input impedance of the duct and then solving an inverse problem. However, extending this procedure to a duct containing several leaks is non-trivial, with the resulting mathematical expressions proving to be highly complex. In this paper, an optimisation approach to the location and sizing of multiple leaks in a duct is described. The approach employs a standard theoretical model of a duct that contains several leaks. The initial parameters of the duct model (e.g. duct radius, number of leaks, leak positions and sizes) are chosen arbitrarily. An optimisation function then adjusts the parameters of the model until its input impedance matches the measured impedance of the duct under investigation. Results are presented which demonstrate the success of this optimisation approach in both locating and sizing multiple leaks in a duct

Heritability of non-speech auditory processing skills

Recent insight into the genetic bases for autism spectrum disorder, dyslexia, stuttering, and language disorders suggest that neurogenetic approaches may also reveal at least one etiology of auditory processing disorder (APD). A person with an APD typically has difficulty understanding speech in background noise despite having normal pure-tone hearing sensitivity. The estimated prevalence of APD may be as high as 10% in the pediatric population, yet the causes are unknown and have not been explored by molecular or genetic approaches. The aim of our study was to determine the heritability of frequency and temporal resolution for auditory signals and speech recognition in noise in 96 identical or fraternal twin pairs, aged 6–11 years. Measures of auditory processing (AP) of non-speech sounds included backward masking (temporal resolution), notched noise masking (spectral resolution), pure-tone frequency discrimination (temporal fine structure sensitivity), and nonsense syllable recognition in noise. We provide evidence of significant heritability, ranging from 0.32 to 0.74, for individual measures of these non-speech-based AP skills that are crucial for understanding spoken language. Identification of specific heritable AP traits such as these serve as a basis to pursue the genetic underpinnings of APD by identifying genetic variants associated with common AP disorders in children and adults

Experimental investigation into noise insulation of straw and reeds / Šiaudų ir nendrių triukšmo izoliacijos eksperimentiniai tyrimai

Sound insulation is mainly affected by the mass or density of the wall. Therefore, in order to compare their effectiveness depending on thickness, the specimens of the same density have been made. Sound insulation also depends on sound frequency, and therefore frequency dependent analysis has been conducted. Considering all positions of thickness, the effectiveness of sound reduction has been dispersed with deep dips in some specific frequencies. Besides, the effectiveness of straw and different configurations of reeds has been compared with respect to frequency bands. Santrauka Ieškoma vis naujų akustinių problemų sprendimo būdų. Tyrinėjamos naujos ir pamirštos medžiagos, kurių apdorojimo procesas galėtų būti darnus aplinkai. Natūralių atliekinių medžiagų panaudojimas gali būti tvarus sprendimas. Nendrės, apaugančios ežerų, upių ir marių krantus, gali būti pjaunamos natūraliai išdžiūvusios žiemą ir naudojamos kaip konstrukcinė, šilumos izoliacinė arba garso sugerties medžiaga. Šis tyrimas siekė nustatyti šiaudų ir nendrių kaip triukšmo izoliavimo medžiagų galimybes. Triukšmo slopinimo kameroje tirti vienodo tankio (88, 125, 164 kg/m3) skirtingų storių (5, 10, 15, 20 cm) šiaudų ir nendrių bandiniai. Nendrių bandiniai turėjo ryškų rezonanso efektą žemų dažnių srityje. Šiaudų bandiniai efektyviausiai sumažino garso lygį žemų dažnių srityje. Garso lygio sumažėjimo vertės augo didėjant bandinio storiui ir pasiekė 43 dB 3150 Hz srityje 20 cm pailgų nendrių bandinyje. Raktiniai žodžiai: garso lygio sumažėjimas; triukšmo slopi­nimo kamera; šiaudai; nendrė; tvari medžiag