In this work is presented stochastic model of binaural hearing in context of another alternative models. According to latest experimental data on mammals, inhibition plays a role in interaural time difference recognition, which is a key for low frequency sound source localization. The outputs of experiments may lead to the conclusion that the binaural hearing works differently in mammals compared to birds. Nowadays there are a few theoretical works addressing this new phenomena, but all of them are relaying on a very precise inhibition timing, which was never proved as physiologically valid. On the other hand, models described in this work are based on the fact, that every neuron has a random delay when reacting to an excitation. If this time jitter is taken into account and combined with inhibitory signal, delay in the neuronal circuit and coincidence detection, then the output firing rate corresponds to the azimuth of the sound source. In this work it is shown, that such a neuronal circuits are giving the same output results compared to experimental data. The models are supported by analytical computations and numerical simulations including simulation of cochlear implant.

It is increasing number of children who presents deaf behaviors even though their hearing level is into the normal range. These behaviors characterize symptom of the Auditory Processing Disorder which may affect speech and learning development. So it is important the early identification of changes in the auditory processing, especially at preschool age, in order to eliminate and minimize future impairments. Purpose: to describe the auditory processing characteristics of a cohort of five-year-old children. Materials and Methods: a cross-sectional clinic quantitative and exploratory survey carried out with 305 children at the age of five, who are part of a 2005 birth cohort. Behavior and socioeconomic aspects and background history of diseases were searched as well as previous pregnancies and health conditions developed during pregnancy, completion of prenatal, data collection regarding delivery and birth. The evaluation was made in private and public schools through special tests: Sound Localization (SL), Non Verbal Sequential Memory (NVSM), Verbal Sequential Memory (VSM) and Cochlear Palpebral Reflex (CPR). The Chi-square test and Pearson s correlation coefficient were selected for results and risk factors analysis and correlation. Results: While 97% of the children passed in the SL test and 60.4% in the VSM test, 85.5% failed in the NVSM test. Concerning CPR, presence was observed in 99.7% of the sample and no significant difference was verified. Furthermore, no crucial difference was perceived in the results of the tests applied in the sexes and in the schools part of the study. In the quantitative analysis of correct answers, only 11.8% had right answers in all the four tests, however, there was no significant difference. Statistically significant correlation was found between the SL test and the 1st minute Apgar risk factors (p=0.09) and Cephalic Perimeter (p=0.018). Correlation was also observed with the following tests: NVSM and the variable government assistance (p=0.046), and poverty index (p=0.003) and VSM for the variable government assistance (p=0.00) and poverty income (p=0.003). In addition, statistically significant correlation between mother s education and the NVSM (p=0.019) and VSM (p=0.000) tests were found. Conclusion: It was verify a large prevalence of the alteration on auditory behavior on this sample; the adequate Cochlear Palpebral Reflex (CPR) and sound localization were present and Non Verbal Sequential Memory and Verbal Sequential Memory were changed in a significant number of children; the inappropriate conditions of pregnancy and childbirth contributed in improvement of alteration in sound localization. Lower socioeconomic conditions and low maternal education cause negatively influence on development on non-verbal sequential memory and verbal sequential memory skills. / É crescente o número de crianças que apresentam comportamentos compatíveis com perdas auditivas, mesmo possuindo limiares de audibilidade normais. Tal comportamento é característico da Desordem do Processamento Auditivo que pode comprometer a fala e o aprendizado, tornando-se importante à identificação de alterações de processamento auditivo o mais cedo possível, principalmente na fase pré-escolar, para eliminar ou minimizar os prejuízos decorrentes. Objetivo: descrever as características do processamento auditivo de uma coorte de crianças aos 5 anos de idade. Material e Método: pesquisa transversal, clínica, quantitativa e exploratória, realizada com 305 crianças de cinco anos, oriundas de uma coorte de nascimentos de 2005. Foram investigados aspectos comportamentais, socioeconômicos, história pregressa de doenças, gestações anteriores, doenças desenvolvidas durante o período gestacional, realização de pré natal, coleta de dados relativos ao parto e ao nascimento. A avaliação auditiva, realizadas nas escolas públicas e privadas, constou da aplicação de testes especiais de Localização Sonora (LS), Memória Sequencial Não Verbal (MSNV), Memória Sequencial Verbal (MSV) e Pesquisa do Reflexo Cocleopalpebral (RCP). Para análise e correlações dos resultados e fatores de riscos adotados foram utilizados os testes do Qui-quadrado de Pearson. Resultados: Na avaliação foi observado que 97% das crianças passaram no teste de LS, 60,4% no teste de MSV, enquanto que 85,5% falharam no teste de MSNV. O RCP foi observado presença em 99,7% da amostra, não sendo verificada diferença significante entre os testes utilizados. Não houve diferença significativa nos resultados dos testes aplicados entre os gêneros, assim como entre as escolas. Na análise da quantidade de acertos, dentre os quatro testes aplicados foi observado que apenas 11,8% acertaram todos os testes, no entanto, não houve diferença significativa. Foram encontradas associações estatisticamente significantes entre o teste de LS e os fatores de risco Apgar 1º minuto (p=0,09) e Perímetro Cefálico (p=0,018). Bem como ocorreu associações estatisticamente significantes com os testes de MSNV e variável auxílio do governo (p=0,046) e renda per pobreza (p=0,003) e MSV para a variável auxílio do governo (p=0,00) e renda per pobreza (p=0,003). Na sequência, foi constatado associações estatisticamente significantes entre a escolaridade materna e os testes de MSNV (p=,019) e MSV (p= ,000). Conclusões: O comportamento auditivo da maioria das crianças estudadas esteve alterado; o Reflexo Cocleopalpebral e a habilidade auditiva de localização sonora estiveram presentes e adequadas na maioria da amostra e a Memória Sequencial Não Verbal e Memória Sequencial Verbal estiveram alteradas em um número expressivo de crianças; condições ruins de gestação e de parto influenciam negativamente o desenvolvimento da habilidade auditiva de localização sonora e condições socioeconômicas familiares ruins e baixa escolaridade materna influenciam negativamente o desenvolvimento das habilidades auditivas de memória sequencial não verbal e memória sequencial verbal.

Detta kandidatarbete handlar om hur implementation av binauralt ljud kan användas för att öka precisionen för spelares ljudlokalisering i datorspel. I detta arbete skapades en artefakt som testade spelares förmåga att lokalisera ljudkällor på olika vertikala nivåer. Resultatet analyserades och problematiserades med kvantitativa- och kvalitativa undersökningsmetoder. Arbetet kopplas till tidigare forskning inom binauralt ljud och hur det används inom digitala medier. Studien tar även upp ämnen som involverar den mänskliga hörseln och ljudimplementation i datorspel.

In this work is presented stochastic model of binaural hearing in context of another alternative models. According to latest experimental data on mammals, inhibition plays a role in interaural time difference recognition, which is a key for low frequency sound source localization. The outputs of experiments may lead to the conclusion that the binaural hearing works differently in mammals compared to birds. Nowadays there are a few theoretical works addressing this new phenomena, but all of them are relaying on a very precise inhibition timing, which was never proved as physiologically valid. On the other hand, models described in this work are based on the fact, that every neuron has a random delay when reacting to an excitation. If this time jitter is taken into account and combined with inhibitory signal, delay in the neuronal circuit and coincidence detection, then the output firing rate corresponds to the azimuth of the sound source. In this work it is shown, that such a neuronal circuits are giving the same output results compared to experimental data. The models are supported by analytical computations and numerical simulations including simulation of cochlear implant.

Spatial hearing is crucial in real life but deteriorates in participants with severe sensorineural hearing loss or single-sided deafness. This ability can potentially be improved with a unilateral cochlear implant (CI). The present study investigated measures of sound localization in participants with single-sided deafness provided with a CI. Sound localization was measured separately at eight loudspeaker positions (4°, 30°, 60°, and 90°) on the CI side and on the normal-hearing side. Low- and high-frequency noise bursts were used in the tests to investigate possible differences in the processing of interaural time and level differences. Data were compared to normal-hearing adults aged between 20 and 83. In addition, the benefit of the CI in speech understanding in noise was compared to the localization ability. Fifteen out of 18 participants were able to localize signals on the CI side and on the normal-hearing side, although performance was highly variable across participants. Three participants always pointed to the normal-hearing side, irrespective of the location of the signal. The comparison with control data showed that participants had particular difficulties localizing sounds at frontal locations and on the CI side. In contrast to most previous results, participants were able to localize low-frequency signals, although they localized high-frequency signals more accurately. Speech understanding in noise was better with the CI compared to testing without CI, but only at a position where the CI also improved sound localization. Our data suggest that a CI can, to a large extent, restore localization in participants with single-sided deafness. Difficulties may remain at frontal locations and on the CI side. However, speech understanding in noise improves when wearing the CI. The treatment with a CI in these participants might provide real-world benefits, such as improved orientation in traffic and speech understanding in difficult listening situations.

Bakgrund: Förmågan att kunna lokalisera ljud är en binaural process som försvåras i samband med hörselnedsättning, eftersom tillgången till akustiska ledtrådar begränsas. Hörapparattillverkare strävar efter att främja användarnas tillgång till dessa ledtrådar genom nya innovationer. Den vanligaste modellen av hörapparat är i dagsläget bakom-örat-apparaten med högtalarenhet i hörselgången (RIE). Modellens mikrofonplacering bakom örat tillåter inte användaren att utnyttja öronmusslans akustiska egenskaper som hjälper vid ljudlokalisation. En hörapparattillverkare har därför tagit fram en ny teknik (M&RIE) som implementerar en ytterligare mikrofon placerad i hörselgången som bland annat syftar till att gynna användarens förmåga att lokalisera ljud. Syftet med denna studie är att undersöka ljudlokalisationsförmågan i horisontalplan med de två högtalarenheterna “M&RIE” och “RIE” hos normalhörande vuxna. Metod: 18 normalhörande deltagare genomförde tre lokalisationstest med respektive teknik. Signalerna i testen bestod av ett pulserande brus, en biltuta samt en ringklocka. Resultat: RIE presterade generellt bättre än M&RIE i lokalisationstestet vid samtliga signaler. En mindre andel bak-fram-förväxlingar skedde vid lokalisation med RIE än med M&RIE. Slutsatser: Den begränsande faktorn att M&RIE behöver anpassas med täta domer leder till nackdel i lokalisationsförmåga vid anpassning för mild hörselnedsättning. Undersökningen indikerar att fördelen av en öppen anpassning hos RIE är större än fördelen av en extra mikrofon i hörselgången för normalhörande deltagare vid horisontell ljudlokalisation. / Background: The ability to localize sounds is a binaural process that is limited by hearing loss due to a decreased access to acoustic cues. Hearing aid manufacturers strive to promote users' access to these cues through new innovations. Currently, the most common type of hearing aid is the behind-the-ear device with the speaker unit located in the ear canal (RIE). The model's microphone placement behind the ear does not allow the user to take advantage of the acoustic properties of the pinna, which aid sound localization. Therefore, a hearing aid manufacturer has developed a new technology (M&RIE) that implements an additional microphone placed in the ear canal, which aims to benefit its users' ability to locate sounds. Aim: The aim of this study is to investigate the ability to locate sound in the horizontal plane using the two speaker units "M&RIE" and "RIE" in normal-hearing adults. Methods: 18 normal-hearing participants performed three localization tests with each technology. The signals in the tests consisted of a pulsating noise, a car horn, and a bicycle bell. Results: RIE generally outperformed M&RIE in the localization test for all signals. A lower percentage of back-front-confusions occurred in localization with RIE than with M&RIE. Conclusions: The limiting factor that M&RIE must be fitted with occluded domes leads to a disadvantage in the localization ability when fitted for mild hearing loss. The study indicates that the advantage of an open-fit in RIE is greater than the advantage of an extra microphone in the ear canal for normal-hearing participants in horizontal sound localization.

No description available.

The encoding of auditory spatial acuity (measured as the precision to distinguish between two spatially distinct stimuli) by neural circuits in both auditory cortices is a matter of ongoing research. Here, the event-related potential (ERP) mismatch negativity (MMN), a sensitive indicator of preattentive auditory change detection, was used to tap into the underlying mechanism of cortical representation of auditory spatial information. We characterized the MMN response affected by the degree of spatial deviance in lateral acoustic space using a passive oddball paradigm. Two stimulation conditions (SCs)—specifically focusing on the investigation of the mid- and far-lateral acoustic space—were considered: (1) 65° left standard position with deviant positions at 70, 75, and 80°; and (2) 95° left standard position with deviant positions at 90, 85, and 80°. Additionally, behavioral data on the minimum audible angle (MAA) were acquired for the respective standard positions (65, 95° left) to quantify spatial discrimination in separating distinct sound sources. The two measurements disclosed the linkage between the (preattentive) MMN response and the (attentive) behavioral threshold. At 65° spatial deviations as small as 5° reliably elicited MMNs. Thereby, the MMN amplitudes monotonously increased as a function of spatial deviation. At 95°, spatial deviations of 15° were necessary to elicit a valid MMN. The behavioral data, however, yielded no difference in mean MAA thresholds for position 65 and 95°. The different effects of laterality on MMN responses and MAA thresholds suggest a role of spatial selective attention mechanisms particularly relevant in active discrimination of neighboring sound sources, especially in the lateral acoustic space.

Objective assessment for the effect of hearing protectors, background noise levels, and backup alarm acoustic features on listeners' abilities to localize backup alarm signals in the horizontal dimension, as well as on their ability to detect backup alarm signals in the distance dimension, is lacking in the acoustics and safety literature. Accordingly, two research experiments were conducted for this dissertation. In the first experiment, the effect of seven hearing protectors, two background pink noise levels (60 dBA and 90 dBA), and two backup alarm signals (standard and spectrally-modified) on the ability of normal hearing listeners to localize backup alarm signals in the horizontal dimension was investigated. Results indicated that a diotic sound transmission earmuff significantly degraded localization accuracy as compared to all other hearing protectors and the open ear condition. In addition, no significant difference existed between the open ear condition and the other hearing protectors in localization accuracy in most of the conditions tested. However, the E-A-R/3M HiFiTM earplug was advantageous in localization performance since it provided a significantly higher percentage correct localization than the Moldex foam earplug, the diotic earmuff, and the dichotic earmuff in 90 dBA pink noise. As for main effects of the other independent variables, the 90 dBA pink noise significantly degraded localization performance as compared to the quiet condition of 60 dBA, and a spectrally-modified backup alarm significantly improved localization performance as compared to the standard (narrowband) backup alarm. Potential application of these results includes the revision of backup alarm standards. In addition, these results provide clear advice for safety professionals to avoid the application of diotic sound transmission earmuffs for workers if localizing backup alarms is important. In the first experiment, listeners' feeling of comfort for each hearing protector was assessed subjectively by using a comfort rating scale. In addition, a subjective assessment for listeners' confidence in their localization decisions was established. Results indicated no significant difference between the hearing protectors in terms of comfort. However, in terms of listeners' confidence in localization decisions, their confidence was significantly degraded when they were fitted with the diotic earmuff. By contrast, they showed significantly more confidence in their localization decisions when they were fitted with the E-A-R/3M HiFi™ earplug as compared to when they were fitted with the Moldex foam earplug, the E-A-R/3M Ultrafit™ earplug, and the Bilsom passive earmuff. In the second experiment, listeners' performance in detecting a stationary backup alarm signal, including both a standard (narrowband) and broadband (pulsed white noise) alarm, was determined while they were equipped with various passive and electronic hearing protection devices. Listeners' performance was quantified by detection distance, which was defined as the distance between the stationary backup alarm device and the position where the listener detected the backup alarm signal. The resultant data demonstrated that normal hearing listeners detected a standard (narrowband) backup alarm signal at significantly longer distances as compared to the broadband (Brigade™) backup alarm signal, thus indicating the earlier forewarning by the standard alarm. In addition, passive hearing protection devices characterized with high attenuation significantly reduced the detection distance. These results may be applied to assist safety professionals in selecting hearing protectors and backup alarm signals that provide on-foot workers with ample time to react to an approaching backing vehicle, thus improving their safety. / Ph. D.

No description available.