Audio in today’s first person computer games plays a vital role in informing players about their surroundings as well as general gameplay elements. Awareness of the direction, distance, and spatial placement of audio sources can be crucial for players in various contexts. Spatialising audio through stereo panning can pose challenges to players when it comes to accurately localising sound sources in front, behind, below, or above the player. Binaural audio is another technique used for spatialising audio by simulating how sound interacts with the head and ears before reaching the eardrums from a specific direction before the signal is rendered through the headphones. While binaural audio attempts to alleviate the front-back confusion, the cues from binaural audio are lost when the listener moves their head if some form of head tracking solution is not incorporated. Hence, this study’s research question is: ”How is localisation of audio sources in first-person computer games — while wearing headphones— helped by spatialising the soundscape in relation to head movement utilising head tracking technology?”. To be able to answer the research question a prototype of a game was developed following design science guidelines. The objective was to timely and accurately localise 14 invisible targets emitting sound in a virtual three-storey house. During one half of the test the spatilisation with head movements was inactive and the other half had it activated in order to compare the testers ability for localisation with and without the tool. The order for which half would have spatilisation activated was randomised for each test. The research strategy consisted of two types of experiments, blind — with 20 participants, and open — with five testers, that were conducted to measure and evaluate the participants’ head movement and performance in terms of accuracy and time of localising the targets by shooting them. For data collection this study used a mixed methods approach that included questionnaires with closed questions and semistructured interviews. Data about the testers’ performance was automatically logged during the test. The results from the first, blind experiment showed little head movement and no significant impact on localisation performance from the spatialisation. Consequently an open follow-up experiment was performed to discover if the blind experiment design affected the results. The results demonstrated a higher degree of head movement but corroborated the first test in no substantial effect on the testers’ accuracy or time when localising the targets. In summary, there could be found no positive or negative impact on one’s localisation of audio sources in first-person computer games —while wearing headphones— when spatialising the soundscape in relation to head movements by utilising head tracking technology. Additionally, some participants found the tool to be unfit for the genre that the prototype resembled and suggested that spatialisation of audio with head tracking could perhaps be better suited for other genres. This could serve as material for future research on the use of head tracking for spatialisation of audio in computer games.

Due to the covid-19 pandemic, companies and schools had to online go for meetings. With the opening of countries, people can now choose to attend meetings both physically and remotely which has led to the evolution of hybrid meetings. This thesis project focuses on how the perceived presence could be enhanced for remote participants. The purpose of the research is to explore the technology of dynamic binaural audio in the context of hybrid meetings and what the effects are on the remote participants.The paper presents the results through observations and interviews with the case study group, in combination with different literature studies. With the findings, a prototype for dynamic binaural audio has been developed and user-tested. As result, the remote participants reported a higher perceived presence with the implementation of dynamic binaural audio. Although, the implementation of dynamic binaural audio together with a static two dimensional video left some remote participants with a lower perceived presence due to asynchrony.

The goal of this study was to explore the potential of using video games with binaural beats as an alternative to regular binaural beat therapy. As previous studies have shown, music therapy, binaural beat therapy, and video games have been used for relaxation purposes to varying success. To prove this, three types of therapies were held in order to test their effectiveness. 16 students participated in the test in which their goal was to partake in one of the three therapy sessions, with two interviews before and after the therapy session. The results showed that a video game therapy with binaural beats could work as an alternative to a standard music therapy session, and that the binaural beats improved the relaxing factor in a video game. However, this area of study is quite new, which means more studies would be needed to ascertain the effectiveness of this kind of therapy. / <p>Det finns övrigt digitalt material (t.ex. film-, bild- eller ljudfiler) eller modeller/artefakter tillhörande examensarbetet som ska skickas till arkivet.</p>

Auditory neurons selectively respond to frequency and amplitude of sound. In the auditory midbrain, duration-tuned neurons (DTNs) are subsets of neurons that selectively respond to the duration of sound. DTNs may help further understand the neural mechanism underlying temporal processing in the central nervous system. Temporal processing has been shown to play important roles in speech, discriminating species-specific signals, and echolocation. The goal of this thesis is to explore the role of DTNs through single-unit electrophysiological recordings in the auditory midbrain of the big brown bat (Eptesicus fuscus). Monotic and dichotic paired-tone stimulation was used to evoke excitatory and inhibitory responses from DTNs. Two stimuli consisted of best duration (BD) excitatory and non-excitatory (NE) tones. In the monotic condition, both tones were presented to the contralateral ear, and when they were close in time, the NE tone always suppressed spikes evoked by the BD tone. In the dichotic condition, the BD tone was presented to the contralateral ear. The NE tone was presented to the ipsilateral ear and suppressed BD tone evoked spiking in ~50% of cells. Properties of the ipsilaterally-evoked inhibition were investigated by varying the frequency of the NE tone from the best excitatory frequency (BEF), throughout a cell’s excitatory bandwidth (eBW). We measured the inhibitory frequency response area, best inhibitory frequency (BIF), and inhibitory bandwidth (iBW) of each cell. We found inhibition became weaker as the frequency of the NE tone moved further from the middle of the eBW. We found that a DTN’s BEF and BIF closely matched, but the eBW was broader than the iBW and overlapped the iBW measured from the same cell. This suggests temporal selectivity of midbrain DTNs are created by monaural inputs, with binaural inputs playing a lesser role in shaping duration selectivity. / Thesis / Master of Science (MSc)

This dissertation aims to develop a formal foundation to design an adaptive output feedback predictor for a class of unknown systems where parameters and order are unknown or high-dimensional. We present a reduced-order adaptive output-predictor scheme based on modal reduction and Lyapunov's method. Moreover, the credibility of the proposed reduced-order adaptive output-predictor scheme is validated by mathematical proof, and numerical and experimental studies, such as single pendulum, double pendulum, six-link pendulum, rope as a high-dimensional rope, and EEG data. Then the dissertation goal is to experimentally validate the proposed reduced-order model parameterization technique for tracking uncertain linear time-invariant (LTI) single-input, single-output (SISO) systems. The proposed theory focuses on parameterizing a high-dimensional, uncertain model and introduces a reduced-order adaptive output predictor capable of forecasting the system's output. This predictor utilizes auto-regressive filtered vectors, incorporating the input and output history. The adaptive output predictor is a simplified and known model, making it suitable for controlling high-dimensional, uncertain SISO systems without access to full-state measurements. Specifically, this work establishes the foundation for parameterizing uncertain models, creating a virtual structure that emulates the actual system, and offering a more manageable model for control when the objective is solely to regulate the system's output. The primary focus of this research is to assess the effectiveness and output-tracking capabilities of the proposed approach. These capabilities are extensively examined across diverse platforms and hardware configurations, relying solely on input and output data from the models without incorporating any additional information on the system dynamics. In the first experiment, the predictor's ability to track the angle of a single pendulum, including additional dynamics, is evaluated using only input-output data. The second experiment targets tracking the endpoint of a rope connected to a single pendulum, where the rope emulates a high-dimensional model. A vision system is designed and employed to acquire the rope endpoint position data. Before the rope experiment, a set of experiments is conducted on single pendulum hardware to ensure the accuracy of the vision system's data collection. Comparative analysis between data from object tracking via vision and data acquired through an encoder demonstrates negligible error. Finally, the input and the endpoint output data from the rope experiment are fed into the predictor to assess its capability to track the rope endpoint position without utilizing specific knowledge of the experimental hardware. Achieving negligible error in tracking implies that the predictor provides a simple and accurate representation of the rope dynamics. Consequently, designing a controller for this known model is equivalent to designing a controller for the actual rope system dynamics. The predictor, by closely emulating the behavior of the rope, becomes a reliable surrogate model for control design, simplifying the task of controller design for the complex and uncertain high-dimensional system. Finally, this study introduces a novel approach to enhance controller design for complex brain dynamics by employing a reduced-order adaptive output predictor proposed in [1], fine-tuned with chirp binaural beats. The proposed technique is promising for developing closed-loop controllers in non-invasive brain stimulation therapies, such as binaural beats stimulation, to improve working memory. The study focuses on parameterizing uncertain models and creates a predictor that utilizes auto-regressive filtered vectors to forecast mean phase lock values generated by binaural beats stimulation. The simplified and known model of the predictor proves effective in tracking brain responses, as demonstrated in experiments evaluating its ability to track mean phase locking values. The results indicate negligible tracking error, suggesting the predictor's reliability in representing brain dynamics and simplifying the task of controller design for the complex and uncertain high-dimensional system. / Doctor of Philosophy / This dissertation explores the development of a reduced-order adaptive output predictor for unknown systems with unknown or high-dimensional parameters and order. A reduced-order adaptive output predictor scheme is introduced, validated through mathematical proof, and tested in diverse scenarios, including pendulum systems and EEG data. The focus is on parameterizing uncertain models and creating a simplified adaptive output predictor capable of forecasting system output, specifically for SISO systems. Experimental validation involves tracking the angle of a single pendulum and the endpoint of a high-dimensional rope, demonstrating the predictor's accuracy without detailed knowledge of system dynamics. The study extends its application to complex brain dynamics, using the predictor fine-tuned with chirp binaural beats. Results show promise for developing closed-loop controllers in non-invasive brain stimulation therapies, offering a novel approach to improve working memory via helping to design closed-loop controllers.

This thesis focuses on the mapping of the microphone array’s response to match the characteristics of a human subject’s Head-Related Transfer Function (HRTF). The mapping of the response is first explored with a ‘monaural HRTF matching’ that filters the response independent of the arrival angles. For arbitrary array geometry with the listener external to the acoustic, the monaural HRTF matching did not provide listeners with enough spatial information to precisely localize sound sources. To correct this, a preprocessor control algorithm was added to the HRTF matching, a ‘binaural HRTF matching’ process. The binaural HRTF matching increased the listeners’ performance in perceiving the location of a sound source. With the addition of simulated head movement, the listeners’ perception increased by 20%. An issue with this approach is the use of HRTFs other than the listeners’ measured HRTF, creating a psychoacoustic based error in localization, i.e., front/back confusion. / Master of Science

Detta arbete ämnar att undersöka hur den upplevda rumsstorleken i digitala spel påverkas vid användningen av binauralt ljud i jämförelse med stereoljud. Denna studie relaterar till tidigare forskning inom ljudteknik för digitala spel. För att undersöka frågeställningen skapades en artefakt i form av en digital miljö där målet är att få en uppfattning av vilket av fyra olika rum som känns störst respektive minst. Artefakten är skapad så att det finns två stereomiljöer och två binaurala miljöer. Arbetet har fokuserat på främst kvalitativa metoder men har även inkluderat ett fåtal kvantitativa frågor. Resultatet av dessa sammanställs och analyseras för att fastställa vilken teknik som fungerar bäst gällande upplevd rumsstorlek samt immersionen därav. / <p>Stavningsvarierad titel: Ljudets påverkan på uppfattning av rumsstorlek i spel</p>

Binaural beats är den subjektiva upplevelsen hos någon som, genom hörlurar, exponeras för en ton i ena örat och en ton på en annan frekvens i det andra. Somliga förnimmer differensen mellan de två tonerna som en tredje ton, andra upplever det mer som en spänning. Med hjälp av EEG (Elektroencefalografi), vilket mäter hjärnans elektricitet, har påvisats att det går att reglera hjärnrytmen med hjälp av binaural beats. Det audiella fenomenet förekommer i hjärnforskning inom sömn, meditation och kognition. Vidare har det föreslagits som behandlingsmetod och hjälpmedel vid diagnostisering av vissa neuropsykiatriska besvär. Denna konstnärliga studie utforskar tillämpningen av binaural beats i musikproduktion och musiklyssnande. Det primära syftet är att undersöka om binaural beats kan fungera som ett verktyg inom musikproduktion. Påverkar användandet av binaural beats musikskaparen i den konstnärliga processen? Har binaural beats potential att platsa som ett användbart redskap i den musikaliska verktygslådan? Påverkar förekomsten av ett integrerat binaural beat i ett musikstycke lyssnarens upplevelse på något sätt? Detta har har metodologiskt undersökts genom att komponera musik innehållande binaural beats. Processen har dokumenterats löpande varvat med reflektion för att åskådliggöra om eller hur det har influerat förloppet. Sedan har delar av detta musikaliska material prövats på testpersoner, i en mindre enkätstudie byggd på självskattning, för att se om förekomsten av binaural beats förändrar lyssnarens upplevelse på något vis. Binaural beats påverkade den konstnärliga skapandeprocessen då det genererade inspiration under arbetet. Om det beror på de effekter binaural beats tros ha på hjärnan eller om kreativiteten stimulerades av det faktum att dessa ljud var ett nytt element i det egna musikskapandet kan diskuteras. Resultaten av studiens lyssningsexperiment indikerar inga förändringar hos lyssnarnas upplevelse. Däremot har det gett upphov till idéer kring hur liknande tester skulle kunna utformas för att leda till mer användbara data. De vaga tendenser som förekom skulle kunna vara intressanta att undersöka i en mer omfattande studie.

Aujourd'hui, les technologies de captation et de restitution sonore se développent dans le but de diffuser des scènes avec un rendu spatialisé. Avant leur diffusion, les extraits sonores peuvent être évalués en terme de qualité par des méthodes recommandées par I'Union lnternationale des Télécommunications (évaluation des codecs de compression, procédés de prise ou restitution sonore...). Cependant, ces standards d'évaluation montrent certaines faiblesses notamment en ce qui concerne les attributs de qualité à évaluer. La dimension spatiale n'est pas prise en compte spécifiquement. Dans ce travail, une méthodologie dédiée à l'évaluation de la qualité de I'audio spatialisé est mise en place notamment pour répondre aux biais identifiés. De par l'utilisation d'une catégorisation libre et d'une analyse multidimensionnelle, vingt-huit attributs ont été catégorisés en trois familles d'attributs : le Timbre, l'Espace et les Défauts. Ces trois attributs généraux ont été inclus dans un test d'écoute. Celui-ci se déroule en deux phases : l'évaluation de la qualité globale suivie de l'évaluation des trois attributs simultanément sur une même interface. Les tests sont réalisés sans référence explicite, le fichier original constitue une référence cachée. De plus, trois signaux audio, dit ancrages, spécifiques à chacun des trois attributs ont été définis puis superposés pour définir un ancrage unique triplement dégradé. La méthode a été testée à la fois sur un système de restitution au casque avec des contenus binauraux mais également sur un système multicanal 5.1. L'évaluation de stimuli de qualité intermédiaire est préconisée ainsi que des contenus présentant un effet spatial prononcé. L'évaluation multicritère a montré son intérêt dans certaines conditions et permet ainsi d'identifier les caractéristiques qui sont dégradées. Les attributs Défauts et Timbre ont montré un poids influant sur la qualité globale tandis que le poids de I'attribut Espace est plus discutable. / Nowadays, recording and restitution technologies focus on a spatial rendering of sound. Before their broadcast, the quality evaluation of sound excerpts is often necessary. Methods recommended by the international telecommunication union denote some weaknesses about sound attributes to be evaluated.For example, spatial dimension is barely taken into account. A methodology dedicated to the assessment of spatial audio quality is proposed in order to avoid some biases. With a free categorization and a multidimensional scaling, 28 attributes were clustered in three families '. Timbre, Space and Defecfs. These three categories were included in a listening test split into two sessions : first, the assessment of overall quality and then, the evaluation of the three categories presented simultaneously on a same interface.Tests were conducted without explicit reference, but, the original version was considered as a hidden reference. Moreover, three specific anchors, each one associated to dedicated categories, were defined and then were mixed to define a unique anchor impaired in three ways. The method was tested on a 5.1 system and on binaural contents with headphone restitution. lntermediate quality of contents is recommended as well as contents with relevant spatial effects. The interest of a multicriteria assessment is to identify which properties of sound are impaired. Linear regression shows that Defecfs and Timbre attributes have influential weight on overall quality while the weight of Space attribute is more dubious.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The modeling of reverberant environments using techniques based on geometry, such as Ray Tracing or behavior-based wave, such as Finite Elements are devoted respectively to large and small places . But the great difficulty arises in the simulation of medium enclosures, based on precision to the geometrical approach and the computational cost for the behavior-based wave. Therefore, the objective of this work is to obtain Impulse Response Room (Room Impulse Response - RIR ) in midsize through technical Digital Waveguide Mesh ( Digital Waveguide Mesh - DWG ) environments . During the simulations the excitation was made by a half-sine, representing an approximation of the Dirac Delta. To simulate the reverberant field, were explored different geometries of meshes. Applying the results obtained it was possible to predict numerically the acoustic behavior of a sample of the same audio playing through the auralization. Added to this, certain parameters of acoustic quality which are directly derived from the RIR could be calculated . Finally, a comparative study of the RIR obtained experimentally , theoretically and via DWG was performed . From the initial proposal of the work , we have reached a computational tool able to predict the acoustic behavior in two and three dimensional environments , a relatively low computational time and quality in their results . Therefore , it was possible to make a preliminary analysis of the acoustic quality of the room , including allowing the sound reproduced in the virtual room. / A modelagem de ambientes reverberantes por meio de técnicas baseadas na geometria, como o Ray Tracing ou na propagação de ondas acústica, como Elementos Finitos são consagrados respectivamente para recintos de grande e pequeno porte. Porém, a grande dificuldade reside na simulação dos recintos médios, em função da precisão, para a abordagem geométrica, e do custo computacional, para os baseados no comportamento da onda. Assim sendo, o objetivo deste trabalho consiste na obtenção da Resposta Impulsiva da Sala (Room Impulse Response RIR) em ambientes de médio porte por meio da técnica de Malhas de Guias Digitais de Ondas (Digital Waveguide Mesh DWG). Durante as simulações a excitação se deu por meio de um meio seno, representando uma aproximação do Delta de Dirac. Para simular o campo reverberante, foram exploradas diferentes geometrias de malhas. Aplicando os resultados obtidos numericamente foi possível prever o comportamento sonoro de uma amostra de áudio sendo reproduzida no mesmo, por meio da auralização. Somado a isso, certos parâmetros da qualidade acústica, que são diretamente derivados da RIR puderam ser calculados. Para finalizar, um estudo comparativo das RIR obtidas experimentalmente, teoricamente e via DWG foi realizado. A partir da proposta inicial do trabalho, chegou-se a uma ferramenta computacional capaz de prever o comportamento acústico em ambientes bi e tridimensionais, num tempo computacional, relativamente baixo e com qualidade em seus resultados. Por conseguinte, foi possível fazer uma análise prévia da qualidade acústica da sala, inclusive permitindo ouvir o som reproduzido no recinto virtual. / Doutor em Engenharia Mecânica