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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.
1

En effektiv lektion : En interventionsstudie kring akustikåtgärder och taluppfattbarhet hos en femteklass / An effective class : An interventional study of how changes in room acoustics affect speech intelligibility and time efficiency in a fifth grade class

Holm, Sebastian, Lagerberg, Petra January 2015 (has links)
Detta är en interventionsstudie av hur rumsakustiken i ett klassrum påverkar en lektion beträffande tidseffektivisering samt taluppfattbarhet. Studien jämför resultat av olika mätningar och tester före och efter en rumsakustisk åtgärd i form av ett nedpendlat akustiktak. Åtgärden utförs i ett klassrum på S:t Hansskolan i Visby, i syfte att undersöka huruvida en förbättring av ljudmiljön i klassrummet kan ge positiva samhällsekonomiska effekter. De mätningar och tester som genomförts ger tillsammans en bild av klassrummets akustiska egenskaper före och efter åtgärden. Mätningarna innefattar tidtagning av uppstartstid av en lektion samt olika rumsakustiska mätningar och tester beträffande taluppfattbarhet. Mätningar visar att klassrummets ljudmiljö efter den rumsakustiska åtgärden har förbättrats med kortare efterklangstider, förbättrade förhållanden med rummets reflexer samt ett förbättrat talöverföringsindex. Även ett lyssningstest har genomförts och resultaten visar att taluppfattbarheten har ökats. Lärarens tidtagning visar att uppstartstiden förkortats med åtminstone 15 minuter per vecka. Sammantaget visar studien att den rumsakustiska åtgärden inneburit en ökning i nyttjad lektionstid som dessutom blivit mer effektiv genom en uppmätt ökad taluppfattbarhet. Observerade nyttoeffekter anses väga tyngre än investeringskostnaden till den grad att installationen rekommenderas till befintliga skolmiljöer och inte bara vid nyproduktion. / This is an interventional study of how classroom acoustics affects a class in regards to time effectiveness and speech intelligibility. The study compares results of measurements and tests before and after acoustical treatments in the form of a new acoustic ceiling. The treatments are made in a classroom in S:t Hansskolan elementary school, with the aim to see whether an improvement in room acoustics can lead to socio economic gains through an increase in the effective time for a lesson. The combined measurements and tests show the state of the acoustical environment before and after the treatments. Measurements includes the time it takes to get a lesson going, as well as various acoustical measurements and tests regarding speech intelligibility. Results shows that the room acoustics have improved with reduced reverberation times, an increase in early reflexes compared to late, as well as improved speech transmission index values. The class also scores higher on hearing in noise tests, which implies an increase in speech intelligibility. The teacher’s timekeeping shows that the time it takes to start classes has shortened by at least 15 minutes per week. On a whole the study shows that the acoustic treatments has led to an increase in use of planned time for each lesson, which through increased speech intelligibility also has become more effective. Observed socio economic effects outweigh the cost of the installation to the point that it is recommended not only to new classrooms but also to existing school environments.
2

Taluppfattbarhet med strupmikrofon / Speech intelligibility with throat microphone

Wickman, Erik January 2018 (has links)
Contact microphones, especially throat microphones, have been developed to be used in environments with high background noises to improve the speech intelligibility in communication. They pick up vibrations from the surface they are attached to and are therefore less sensitive to sound and noise from the air. Comparison of the speech intelligibility with other types of microphones have previously been done by letting test persons examine the communication devices in question. This study examines the possibility to make use of the STI-method instead and therefore make a comparison faster, more cost-efficient and customizable. The thought is that if the relationship between speech signals and vibrations were known, it could be used to transform the STI test signal to vibrations and then use the STImethod to estimate the speech intelligibility for the chosen contact microphone. This study, containing 22 men and women, evaluated the vibrations at the most suitable locations on the head for contact microphones and compared it with the speech signal of the same test person. Frequency responses were calculated for all locations of the head and a more detailed study showed that the frequency response of the neck may be approximated as a second order lowpass filter with a cut-off frequency of about 300 Hz that attenuates speech signals with higher frequencies. Experiments were also done to measure the STI value of a throat microphone with the known relationship. However, the results pointed out several problems that needs to be addressed before a STI method can be performed successfully. The results from this study may also be used to deeper study the relationships between different vibrations resulting from speech signals and suggestions on how the performance of contact microphones may be improved are given.
3

Perceptually meaningful time and frequency resolution in applying dialogue enhancement in noisy environments : Dialogue Enhancement research

PATIL, SUSHANTH January 2023 (has links)
Dialogue Enhancement (DE) is a process used in audio delivery systems to improve the clarity, intelligibility, and overall quality of the spoken dialogue in audio content. It is primarily used when dialogue is masked by music, surrounding noise, or other audio sources. This thesis project involves experiments to find the optimal time and frequency resolution needed for a DE system. The time resolution focuses on experimenting with various attack/release times for a DE system. The frequency domain analysis investigates whether people prefer a noise spectrum-dependent gain over a conventional full-band gain. The research methodology comprises three main parts. The first part focuses on system setup and choosing content/vectors to be used for the experiments. Next, the experiments are designed for time and frequency resolution. An exponential smoothing model is used to amplify/attenuate the dialogue stream at various times of attack/release. For the frequency counterpart, a banded gain model is designed which uses banded noise levels as input. Subsequently, a modified subjective listening test is designed to evaluate the experiments designed. The responses recorded for various types of content-noise combinations from the listeners are recorded and analyzed. Finally, the main outcome of this research emphasizes the advantages of a DE system. Further, it paves the way for further exploration of DE models and rigorous testing schemes with expert listeners. / Dialogue Enhancement (DE) är en process som används i ljudleveranssystem för att förbättra tydligheten, förståeligheten och den övergripande kvaliteten på den talade dialogen i ljudinnehåll. Det används främst när dialog maskeras av musik, omgivande brus eller andra ljudkällor. Detta examensarbete omfattar experiment för att hitta den optimala tids- och frekvensupplösningen för ett DEsystem. Tidsupplösningsexperimenten fokuserar på olika attack- och releasetider för ett DE-system. Frekvensdomänanalysen undersöker om människor föredrar en brusspektrumberoende förstärkning framför en konventionell fullbandsförstärkning. Forskningsmetodiken består av tre huvuddelar. Den första delen fokuserar på systeminställning och val av innehåll/vektorer som ska användas för experimenten. Därefter designas tids- och frekvensupplösningsexperimenten. En exponentiell tidsenvelopp används för att förstärka/dämpa dialogen vid olika tider för attack/release. För frekvensdomänexperimenten används en bandad förstärkningsmodell som använder bandade brusnivåer som insignal. I den tredje delen utformas ett subjektivt lyssningstest för att utvärdera experimenten. Lyssnarnas svar för olika typer av innehåll-bruskombinationer registreras och analyseras. Det huvudsakliga resultatet av denna forskning betonar fördelarna med ett DEsystem. Vidare banar det väg för utforskning av fler DE-modeller och rigorösa testscheman med expertlyssnare.

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