Image modeling is a foundation for many image processing applications. The compound Gauss-Markov (CGM) image model has been proven useful in picture restoration for natural images. In contrast, other Markov Random Fields (MRF) such as Gaussian MRF models are specialized on segmentation for texture image. The CGM image is restored in two steps iteratively: restoring the line field by the assumed image field and restoring the image field by the just computed line field. The line fields are most important for a successful CGM modeling. A convincing line fields should be fair on both fields: horizontal and vertical lines. The working order and update occasions have great effects on the results of line fields in iterative computation procedures. The above two techniques are the basic for our research in finding the best modeling for CGM. Besides, we impose an extra condition for a line to exist to compensate the bias of line fields. This condition is based upon a requirement of a brightness contrast on the line field. Our best modeling is verified by the effect of image restoration in visual quality and numerical values for natural images. Furthermore, an artificial image generated by CGM is tested to prove that our best modeling is correct.

The interaural level difference (ILD) is a sound localization cue first computed in the lateral superior olive (LSO) by comparing the loudness of sounds between the two ears. In the auditory cortex, one class of neurons is excited by contralateral but not ipsilateral monaural sounds. These "EO" neurons prefer ILDs where contralateral sounds are louder than ipsilateral sounds. Another class, the "PB" neurons, are unresponsive to monaural sounds but respond predominantly to binaural ILDs, when both ears receive simultaneous sounds of roughly equal loudness (0 ILD). Behavioral studies show that ILD sensitivity is invariant to increasing sound levels. However, in the LSO, ILD response functions shift towards the excitatory ear as sound level increases, indicating level-dependence. Thus, changes in firing rate can indicate either a change in sound location or sound level, or both. This suggests a transformation in level-sensitivity between the LSO and the perception of sound sources, yet the location of this transformation remains unknown. I performed recordings in the auditory cortex of the rat to test whether neurons were invariant to overall sound level. I found that with increasing sound levels, ILD responses were level-dependent, suggesting that level invariance of ILD sensitivity is not present in the rat auditory cortex. In general, neurons follow one of two processing strategies. The tuning of cortical cells typically follows the "inheritance strategy", such that the spiking output of the cell matches that of the excitatory synaptic input. However, cortical tuning can be modified by inhibition in the "local processing strategy". In this case, neurons are prevented from spiking at non-preferred stimuli by inhibition that overwhelms excitation. The tuning strategy of cortical neurons to ILD remains unknown. I performed whole-cell recordings in the anesthetized rat and compared the spiking output with synaptic inputs to ILDs within the same neurons. I found that the PB neurons showed evidence of the local processing strategy, which is a novel role for cortical inhibition, whereas the EO neurons utilized the inheritance strategy. This result suggests that an auditory cortical circuit computes sensitivity for midline ILDs. This dissertation includes previously published/unpublished co-authored material.

Masking Level Difference (MLD) tests are an established component of auditory processing test batteries; however, normative data for these tests vary according to procedure. In this study, forty normal, native-English speaking adults between the ages of 18 and 26 were tested for MLD via a newly developed computer software program using both an adaptive procedure (MLDA) and a Bekesy procedure (MLDB). The results from the two procedures were analyzed for sex differences and compared with each other. For both the MLDA and MLDB, the results showed statistically significant sex differences in the masked thresholds used to obtain the MLD (NoSo and NoSπ), but no significant difference in the calculated MLD value (NoSo - NoSπ). These results suggest that since the MLD was similar for both sexes, the normative data need not be reported separately by sex. The results also showed statistically significant differences between procedures, with the MLDA procedure producing higher MLDs than the MLDB procedure. The MLDA procedure lent itself to a d´ analysis, which could not be determined using MLDB due to the nature of a Bekesy assessment. For MLDA, d´ = 1.4, test sensitivity = 96.4%, and test specificity = 60.3%. The results of this study indicate that MLDA is a better testing procedure due to MLDA's higher MLD average and the statistical data available (d´, and measures of sensitivity and specificity) when using the MLDA procedure.

The purpose of this study was to determine if performances on a 500 Hz MLD task and a word-recognition task in multitalker babble covaried or varied independently for listeners with normal hearing and for listeners with hearing loss. Young listeners with normal hearing (n = 25) and older listeners (25 per decade from 40-80 years, n = 125) with sensorineural hearing loss were studied. Thresholds at 500 and 1000 Hz were ≤30 dB HL and ≤40 dB HL, respectively, with thresholds above 1000 Hz <100 dB HL. There was no systematic relationship between the 500 Hz MLD and word-recognition performance in multitalker babble. Higher SoNo and SπNo thresholds were observed for the older listeners, but the MLDs were the same for all groups. Word recognition in babble in terms of signal-to-babble ratio was on average 6.5 (40- to 49-year-old group) to 10.8 dB (80- to 89-year-old group) poorer for the older listeners with hearing loss. Neither pure-tone thresholds nor word-recognition abilities in quiet accurately predicted word-recognition performance in multitalker babble.

Masking Level Difference (MLD) tests are an established component of auditory processing test batteries; however, normative data for these tests vary according to procedure. In this study, forty normal, native-English speaking adults between the ages of 18 and 26 were tested for MLD via a newly developed computer software program using both an adaptive procedure (MLDA) and a Bekesy procedure (MLDB). The results from the two procedures were analyzed for sex differences and compared with each other. For both the MLDA and MLDB, the results showed statistically significant sex differences in the masked thresholds used to obtain the MLD (NoSo and NoSπ), but no significant difference in the calculated MLD value (NoSo - NoSπ). These results suggest that since the MLD was similar for both sexes, the normative data need not be reported separately by sex. The results also showed statistically significant differences between procedures, with the MLDA procedure producing higher MLDs than the MLDB procedure. The MLDA procedure lent itself to a d´ analysis, which could not be determined using MLDB due to the nature of a Bekesy assessment. For MLDA, d´ = 1.4, test sensitivity = 96.4%, and test specificity = 60.3%. The results of this study indicate that MLDA is a better testing procedure due to MLDA’s higher MLD average and the statistical data available (d´, and measures of sensitivity and specificity) when using the MLDA procedure.

This paper explores how vision affects spatial audio perception in virtual reality. We created four virtual environments with different reverb and room sizes, and recorded binaural clicks in each one. We conducted two experiments: one where participants judged the audio-visual match, and another where they pointed to the click direction. We found that vision influences spatial audio perception and that congruent audio-visual cues improve accuracy. We suggest some implications for virtual reality design and evaluation.

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.

No description available.

Sound localization is a vital aspect of hearing for safe navigation of everyday environments. It is also an important factor in speech intelligibility. This ability is facilitated by the interaural level difference (ILD) cue, which arises from binaural hearing: a sound will be more intense at the nearer ear than the farther. In a hearing-impaired listener, this binaural cue may not be available for use and localization may be diminished. While conventional, bilateral, wide dynamic range compression (WDRC) hearing aids distort the interaural level difference by independently altering sound intensities in each ear, wirelessly-linked devices have been suggested to benefit this task by matching amplification in order to preserve ILD. However, this technology has been shown to have varying degrees of success in aiding speech intelligibility and sound localization. As hearing impairment has wide-ranging adverse impacts to physical and mental health, social activity, and cognition, the task of localization improvement must be urgently addressed. Toward this end, neural modelling techniques are used to determine neural representations of ILD cues for linked and unlinked bilateral WDRC hearing aids. Findings suggest that wirelessly-linked WDRC is preferable over unlinked hearing aids or unaided, hearing-impaired listening, although parameters for optimal benefit are dependent on sound level, frequency content, and preceding sounds. / Thesis / Master of Applied Science (MASc)

För att uppnå ett hållbart samhälle krävs en omställning av transportsystemet. Region Stockholmsmålsättning är att andelen cykelresor ska mer än dubbleras till år 2030 och stå för 20% av alla resor ilänet. Bristande underhåll och dålig utformning på cykelbanor står för ca 60% av allvarligasingelolyckor på cykel. Denna ökning av cykelresor ställer därmed höga krav på utformning ochunderhåll av cykelinfrastrukturen. För att cykelbanans komfort ska vara god, krävs det attcykelbanan är jämn, vilket kan komma i konflikt med brunnslock, då det ofta uppstår sättningar ibeläggningen omkring brunnarna. Brunnslocken kan upplevas som obehagliga att cykla över och haräven lägre friktion än omkringliggande yta. Detta kan resultera i halka vilket särskilt är påtagligt närvägbanan är fuktig. Brunnslock är vanligt förekommande på cykelbanor, i denna studie inventeradesde centrala delarna av elva regionala cykelstråk och där förekom ca 1200 brunnslock. Dessa var avvarierande storlek, position i cykelbanan och höjdläge jämfört med den omkringliggandebeläggningen. Brunnslock kan vara ett potentiellt hinder på cykelbanor, vilket minskar cykelbananstillgängliga bredd. Cykelbanans tillgängliga bredd är den yta som är funktionellt möjlig att cykla på.Konstruerad bredd är däremot den bredd cykelbanan byggdes med utan hänsyn till eventuellahinder.Syftet med studien är att undersöka ifall brunnslock, specifikt manhålsbrunnar och kabelbrunnar,anses vara ett hinder för cyklister på cykelbanor och hur brunnslocken påverkar den tillgängligabredden på de fyra studieplatserna. Den tillgängliga bredden på studieplatserna jämförs medrekommenderade cykelbanebredder i handböcker. Studien avgränsades för att eftersträvastudieplatsernas likvärdighet och att enbart brunnslockens egenskaper skilde studieplatserna åt. Destuderade brunnslocken var: manhålsbrunn med och utan kant samt kabelbrunn med och utan kant.Studiens resultat visar det finns en skillnad mellan situationer med och utan mötande cyklist.Majoriteten av cyklisterna håller sig till höger om brunnslocken oberoende av möte eller ej möte,vilket kan bero på deras naturliga sidledsposition. När det inte är möte väljer många att cykla tillvänster om brunnslocken. Däremot, i situationer med möte väljer nästan ingen att cykla till vänsterom brunnslocken. Minskningen i antal som cyklar vänster om brunnslocken vid möte motsvararungefär ökningen i antal som cyklar höger om brunnslocken i samma situation. Antalet som cyklaröver brunnslock skiljer sig marginellt mellan situationer med och utan möte. Detta kan tolkas somatt cyklister byter sida om brunnslocken och undviker att cykla över dem. Vid de fyra studieplatsernaär det få som cyklar över brunnslocken vilket gör att dessa brunnslock troligen bör ses som etthinder som minskar den tillgängliga bredden.Det kan konstateras att de undersökta kabelbrunnarna är ett större hinder för cyklister änmanhålsbrunnarna. Brunnslock med kant är ett större hinder än brunnslock utan kant. Fler brunnarbehöver studeras innan det går att dra mer generella slutsatser om brunnslock på cykelbanor. Dettagäller både de undersökta brunnarna och andra sorters brunnar.Den tillgängliga bredden på studieplatserna jämfördes med rekommenderade cykelbanebredder idessa handböcker: VGU, GCM-handboken, Stockholms läns regionala cykelplan, Stockholmscykelplan, Cykeln i staden och Solnas cykelplan. Bredderna som rekommenderas i handböckernauppfylls inte sett till den tillgängliga bredden på studieplatserna. / The transport system must transform to achieve a sustainable society. Region Stockholm's goal is forthe proportion of bicycle trips to more than double by 2030 and account for 20% of all trips in thecounty. Lack of maintenance and poor cycle paths account for about 60% of serious single accidentson bicycles. This increase consequently places high demands on the design and maintenance of thebicycle infrastructure. For the cycle path's comfort to be good, it is required that the cycle pathremains even, which can come into conflict with manhole covers, as subsidence often occur at andaround the manholes. The manhole covers can be experienced as unpleasant to cycle over and havelower friction than the surrounding surface. This can cause skidding, especially if the road surface iswet. Manhole covers are common on cycle paths, in this study 1 200 manhole covers were found onthe central parts of eleven regional cycle paths. These were of varying size, position in the cycle pathand height compared to the surrounding pavement. Manhole covers can be a potential obstacle oncycle paths, which reduces the available width of the cycle path. The available width of the cyclepath is the surface that is functionally possible to cycle on. Constructed width, on the other hand, isthe width the cycle path was built with without regard to any obstacles.The purpose of the study is to investigate whether manhole covers are considered an obstacle forcyclists on cycle paths and how the manhole covers affect the available width of the four study sites.The available width of the study sites is compared with recommended cycle path widths inguidelines. The study was delimited to strive for the equivalence of the study sites and that only theproperties of the manhole covers separated the study sites. Two types of manhole covers werestudied and these two types were also studied with and without edges.The results of the study show that there is a difference between situations with and without anoncoming cyclist. A majority of cyclists stay to the right of the manhole covers regardless ofoncoming cyclist or not, which may be due to their natural lateral position. When there is nooncoming cyclist, many choose to cycle to the left of the manhole covers. However, in situations ofencounter, almost no one chooses to cycle to the left of the manhole covers. The decrease in thenumber of cyclists to the left of the manhole covers at an encounter roughly corresponds to theincrease in the number of cyclists to the right of the manhole covers in the same situation. Thenumber who cycle over manhole covers differs marginally between situations with and withoutoncoming cyclists. This can be interpreted as cyclists changing sides of the manhole covers andavoiding cycling over them. At the four study sites, few people cycle over the manhole covers, whichmeans that these manhole covers should probably be seen as an obstacle that reduces the availablewidth.It can be stated that the manhole covers with edges are a greater obstacle than manhole coverswithout edges. More manholes need to be studied before it is possible to draw more generalconclusions about manhole covers on cycle paths. This applies to both the investigated manholesand other types of manholes.The available width of the study places was compared with the recommended cycle path widths inthese guidelines: “VGU”, “GCM-handboken”, “Stockholm County's regional cycle plan”, “Stockholm'scycle plan”, “Cykeln i staden” and “Solna's cycle plan”. The widths recommended in the guidelinesare not met in terms of the available width of the study places.