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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
341

Newborn response to decreased sound pressure level

Tarquinio, Nancy January 1990 (has links)
No description available.
342

Drawing from voice: an exploration of sound in search of representational codes of the unseen

Williams, Carolyn January 2007 (has links)
This project explores the unseen (that which is not considered) in relation to the idea of the existence of another dimension of language. It considers the possibility that, in regard to language, some essential component may have been omitted or unperceived. Through works of art this project explores possibilities for the visual signification of this information. My interest is in exploring ways in which these qualities can be recovered by creating representational codes of the unseen, which evoke a potential for an inclusive language. My enquiry focuses on sound with particular emphasis on 'voice' as a way in which to explore these concepts through visual means. Voice is considered as something which projects or articulates or otherwise could be described as 'speaking'. For example voice is considered in relation to thought, and also the human experience of sound in space. This includes sound generated by self, intrinsic and extrinsic to the body. Voice plays two roles - one as a space from which to retrieve the unseen, and the other as a drawing tool - a way in which to represent what seems unrepresentable.
343

Investigating Student Understanding of Sound as a Longitudinal Wave

Coombs, Earl C. January 2007 (has links) (PDF)
No description available.
344

In-situ Messung der akustischen (Wand-)Impedanz

Nocke, Christian, christian@nocke.de 24 March 2000 (has links)
No description available.
345

The impact of Acoustic and Sound Quality caused by location of impeller rib in blower

Lee, Chen-hsi 10 August 2010 (has links)
Abstract The advances of modern technology , creating a CPU and hardware speed greatly enhance the relative increase in number of work- ing temperature , so as not to make parts for high temperature, shortened life expectancy , we must take active cooling can be resolved , is gener- ated by the use of forced convection fan the heat away , but the fan noise when running , although not damage the hearing , have the potential to affect users of emotions ; as people increasingly rely on the computer, the fan gradually pay attention to the noise problem , so fans of R & D in recent years , in addition to increasing thermal efficiency , the increasing demands for noise. This article will examine the main centrifugal fan to AIO computer system for the experiment; AIO computer is the host and screen into one of the computer system, characterized by the internal space is small, heat is not easy, so the general would choose as the main centrifugal fan cooling fan, but the disadvantage of centrifugal fan noise is high, so this will do for the improvement of centrifugal fan noise research; to change the location of support ribs as the experimental setting, experimental method consists of three steps; first: Analog and down air inlet differences in velocity distribution, the second: the actual measurement centrifugal fan, is divided into single and measurement noise into the system and the sound quality of the judge, the third: performance testing; study showed that support rib in the middle of the design, the noise about 10% area reduction, sound quality also improved the effectiveness of nearly 50%, performance is also about 10% of the upgrade, the support rib in the middle of the design for double inlet centrifugal fans, for the better design.
346

Study on the feeding activity of Cerithium zonatum (Gastropoda:Mesogastropoda) by an acoustic approach

Hsu, Shi-lin 06 September 2010 (has links)
This study focused on a small gastropoda, Cerithium zonatum, found in seagrass meadow at Gui Wan Bi, Green Island, Taiwan. Because this species is high in density in the seagrass meadow and it uses its specific radular to scrap the substrate and emits a particular sound, we can use this acoustic clue to study its feeding activity. C.zonatum samples were collected from Gu Wan Bi, and Zi-Ping Green Island between November to December 2007,March to June 2008, and April to July 2009. It distributes in three habitats (i.e. seagrass¡Bmacro algae¡Brubble) and scrapping sounds were recorded while they were in these habitats. Light and water temperature were treated as experimented factors and their influence on the feeding frequency was deciphered. I also compared individuals of different sizes to find out the differences in feeding frequency between them. SEM was used to observe the radular of C. zonatum. According to the results, I infer that C. zonatum might prefer seagrass meadow as its must suitable microhabitat where feeding activity was higher. Sunlight and high water temperature might lead to increases in feeding activity, but darkness and low water temperature showed opposite effect; it stopped feeding when water temperature had dropped to 17¢J. Scrap frequency of small individuals was higher than larger ones, and their radular were similar in their morphology. I infer that small ones invest more time and energy in feeding in order to grow. Scrapping sound of C.zonatum was compared to Nerita albicilla; there were pulses in the sound of N.albicilla than C. zonatum. It is inferred that this difference might be due to the difference between their radular morphology. I consider that using an bioacoustic approach to study the feeding activity of small gastropoda is feasible.
347

Acoustic characteristics of fine powders in fluidized beds /

Herrera C., Carlos A., January 2000 (has links)
Thesis (Ph. D.)--Lehigh University, 2000. / Includes vita. Includes bibliographical references (leaves 160-165).
348

Sound production in longear sunfish (Lepomis megalotis) : acoustic behavior and geographic variation /

Johnson, Dawn Lee, January 2001 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references (leaves 177-189). Available also in a digital version from Dissertation Abstracts.
349

Investigation and Prediction of the Sound Transmission Loss of Plywood Constructions

Wareing, Robin Richard January 2015 (has links)
The sound transmission loss of a range of plywood panels was measured to investigate the influence of the orthotropic stiffness of the plywood panels. The plywood panels were tested as single and also double leaf partitions, with a range of stud configurations. A new method was developed for predicting the sound transmission loss of single leaf partitions with both orthotropic and frequency dependent stiffness values. The sound transmission loss was evaluated for two significantly different sample sizes. The observed influence of the sample size on the measured sound transmission loss was profound. The construction of the partition was shown to significantly affect the influence of the sample size on the sound transmission loss. A qualitative analysis based on existing published research of the contributing factors is presented, and methods for adjusting the results for the small sample size for comparison with the large results were developed. The influence of a range of acoustic treatments of lightweight plywood partitions was investigated. The treatments involved internal viscoelastic materials and decoupled mass loaded barriers in various arrangements. The attachment between the treatment and the plywood panel was found to influence the sound transmission loss significantly. A prediction method based on published models was modified to allow the influence of the treatments to be included. Reasonable agreement was achieved between the predicted and measured results for a wide range of samples. A prediction method was developed that accounts for the influence of orthotropic, frequency dependent material parameters. This method utilised an adaptive, numerical integration method to solve an analytical formulation for the sound transmission loss. The influence of the finite sample size was accounted for using an expression for the finite panel radiation impedance. The finite panel radiation impedance was predicted analytically and an approximation was also presented. The presence of a significant source room niche was accounted for by applying an appropriate limit to the integration range of the angle of incidence. The prediction methods developed are compared with the measured transmission loss results from both the small and large test facilities. Good agreement was seen for some of the predicted results. Generally the agreement within the coincidence region was worse than for the rest of the transmission loss curve. The inclusion of orthotropic and frequency dependent stiffness values significantly improved the agreement within the coincidence region.
350

Unwanted wanted sounds : Perception of sounds from water structures in urban soundscapes

Rådsten Ekman, Maria January 2015 (has links)
Water structures, for example, fountains, are common design elements in urban open public spaces. Their popularity is probably explained by their visual attractiveness. Less is known about how the sounds of water struc-tures influence the urban soundscape. This thesis explores the potential ef-fects of water sounds on urban soundscapes based on the character of water sounds. Three psychoacoustic studies were conducted in which listeners rated the perceptual properties of various water sounds. Study I found that water sounds had a limited ability to mask traffic noise, as the frequency composition of the sounds resulted in road-traffic noise masking fountain sounds more than the reverse. A partial loudness model of peripheral audito-ry processes overestimated the observed masking effect of water sound on road-traffic noise, and it was suggested that this was related to central pro-cesses, in particular, target/masker confusion. In Study II, water sounds of different degrees of perceived pleasantness were mixed with road-traffic noise to explore the overall effect on soundscape quality. The overall pleas-antness was increased substantially by adding a highly pleasant water sound; however, less pleasant water sounds had no effect or even reduced overall pleasantness. This result suggests that the perceptual properties of water-generated sounds should be taken into consideration in soundscape design. In Study III, this was explored by analyzing a large set of recordings of sounds of water fountains in urban open spaces. A multidimensional scaling analysis of similarity sortings of sounds revealed distinct groups of percep-tually different fountain sounds. The group of pleasant fountain sounds was characterized by relatively low loudness and high fluctuation strength and tonality, generating purling and rippling sounds. The group of unpleasant fountain sounds was characterized by high loudness and low fluctuation strength and tonality, generating a steady-state like noisy sound.. A joint result of all three studies is that sounds from water structures with a high flow rate (i.e., a large jet and basin in Study I, a waterfall in Study II, and large fountains in Study III) generating a steady-state noisy sound should be avoided in soundscape design. Instead, soundscape design might better focus on more fluctuating water sounds, which were considered more pleasant in both studies II and III. A general conclusion from this thesis is that water-generated sounds may be used to improve the soundscape, but that great care must be taken in selecting the type of water sound to use. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Manuscript.</p>

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