The sound insulation of single leaf finite size rectangular plywood panels with orthotropic frequency dependent bending stiffness

Current theories for predicting the sound insulation of orthotropic materials are limited to a small range of infinite panels. This paper presents a method that allows for the prediction of the sound insulation of a finite size orthotropic panel. This method uses an equation for the forced radiation impedance of a finite size rectangular panel. This approach produces an equation that has three nested integrals. The long numerical calculation times were reduced by using approximate formulas for the azimuthally averaged forced radiation impedance. This reduced the number of nested integrals from three to two. The resulting predictions are compared to results measured using two sample sizes of four different thicknesses of plywood and one sample size of another three different thicknesses of plywood. Plywood was used for all the tests because it is somewhat orthotropic. It was found during testing that the Young's moduli of the plywood were dependent on the frequency of excitation. The influence of the frequency dependent Young's moduli was then included in the prediction method. The experimental results were also compared with a simple isotropic prediction method.

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Speed of sound in diseased liver observed by scanning acoustic microscopy with 80 MHz and 250 MHz

In this study, the speed of sound(SOS) of two types of rat livers (eight normal livers, four cirrhotic livers) was measured with a scanning acoustic microscope using two transducers, one of which had an 80-MHz and the other a 250-MHz center frequency. The 250-MHz transducer had a better spatial resolution adapted to studying fiber or hepatic parenchymal cells. In normal livers, averages of the SOS values were from 1598 to 1677 m/s at 80-MHz and from 1568 to 1668 m/s at 250-MHz. In the fiber tissue of cirrhotic livers, averages of the SOS values were from 1645 to 1658 m/s at 80-MHz and from 1610 to 1695 m/s at 250-MHz, while the SOS values in the other tissue of cirrhotic livers ranged from 1644 to 1709 m/s at 80-MHz and from 1641 to 1715 m/s at 250-MHz. In one liver,SOS in fiber tissue was larger than that of tissues without fiber while in others it was lower. The resulting two-dimensional SOS maps provide a unique quantitative insight of liver acoustic microstructures in a healthy liver and in a cirrhotic ones. This study would be helpful to understand the complex relationship between acoustic properties and liver disease including fiber tissue.

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Vanderbilt Audiology's Journal Club: Noise Reduction, Directional Microphones, and Listening Effort

Dr. Gus Mueller:  Our presenter today for our Vanderbilt Journal Club is Dr. Erin Picou.  We are fortunate to have someone talking about current hearing aid research who also is conducting and publishing her own research in this area. 

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Everybody on your Feet! Introducing Cheer!

This course is an introduction to the Cheer family of products. Cheer is a well-balanced line-up of Sonic products featuring impressive sound quality statistics. Anyone who has ever fit a Sonic product knows the natural component of sound is something that we hold near and dear to our hearts. Today, we are going to talk about all of the things that are important to Cheer. First and foremost is the sound. Natural sound begins with a sound processor that is engineered for premium quality. We have an industry-acclaimed system.

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Phonak CROS II

Editor’s Note: This text course is an edited transcript of a live webinar. Download supplemental course materials.Learning ObjectivesAt the conclusion of this course, you will be able to describe the different wireless CROS and Bi-CROS solution

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The effect of weight-bearing asymmetry on dynamic postural stability in healthy young individuals

Publication date: March 2016
Source:Gait & Posture, Volume 45
Author(s): Digna de Kam, Jip. F. Kamphuis, Vivian Weerdesteyn, Alexander C.H. Geurts
BackgroundIn people with lateralized disorders, such as stroke, Weight-Bearing Asymmetry (WBA) is common. It is associated with postural instability, however, WBA is one of several abnormalities that may affect postural stability in these disorders. Therefore, we investigated the isolated effects of WBA on dynamic postural stability in healthy individuals.MethodsTen young participants were subjected to multidirectional stance perturbations by support surface translations at three levels of WBA (0, 10 and 20% of body weight unloading of one leg). The stepping threshold was determined iteratively for each condition and in four perturbation directions (forward, backward, leftward and rightward). The stepping threshold was defined as the highest perturbation intensity recovered from with a feet-in-place response. The Margin of Stability (MOS) at the stepping threshold was defined as the smallest distance between the vertical projection of the Extrapolated Center of Mass (XCOM) and the edge of the base of support.ResultsWBA decreased the stepping threshold (stability decreased) for perturbations towards the loaded side (translations towards the unloaded side), whereas it increased stepping thresholds for perturbations towards the unloaded side. No significant effects of WBA were found on the MOS. WBA increased the frequency of stepping with the unloaded leg upon forward and backward perturbations.ConclusionWBA increased dynamic stability towards the unloaded leg following external balance perturbations and resulted in a greater probability of stepping with this leg. Future studies are needed to evaluate the functional significance of these WBA-related effects on postural stability in people with lateralized disorders.



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Toddlers' Verb Lexicon Diversity and Grammatical Outcomes

Purpose

The goals of this study were to quantify longitudinal expectations for verb lexicon growth and to determine whether verb lexicon measures were better predictors of later grammatical outcomes than noun lexicon measures.

Method

Longitudinal parent-report measures from the MacArthur-Bates Communicative Development Inventory (Fenson et al., 2007) from ages 21 to 30 months from an archival database were used to model growth in common noun and verb lexicon size for 45 typically developing toddlers. Communicative Development Inventory growth coefficients and 24-month measures of lexical diversity from spontaneous language samples were used to predict 30-month grammatical outcomes on the Index of Productive Syntax (Scarborough, 1990).

Results

Average verb growth was characterized by 50.57 verbs at 24 months, with linear growth of 8.29 verbs per month and deceleration overall. Children with small verb lexicons or slow linear growth at 24 months accelerated during this developmental period. Verb lexicon measures were better predictors of grammatical outcomes than noun lexicon measures, accounting for 47.8% of the variance in Index of Productive Syntax scores. Lexical verb diversity in spontaneous speech emerged as the single best predictor.

Conclusion

Measures of verb lexicon size and diversity should be included as part of early language assessment to guide clinical decision making with young children at risk for language impairment.

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