A natural auditory scene contains many sound sources each of which produces complex sounds. These sounds overlap and reach our ears at the same time, but they also change constantly. To still be able to follow the sound source of interest, the auditory system must decide where each individual tone belongs to and integrate this information over time. For well-controlled investigations on the mechanisms behind this challenging task, sound sources need to be simulated in the lab. This is mostly done with sine tones arranged in certain spectrotemporal patterns. The vast majority of studies simply interleave two sub-sequences of sine tones. Participants report how they perceive these sequences or they perform a task whose performance measure allows hints on how the scene was perceived. While many important insights have been gained with this procedure, the questions that can be addressed with it are limited and the commonly used response methods are partly susceptible to distortions or only indirect measures. The present thesis enlarged the complexity of the tone sequences and the diversity of perceptual measures used for investigations on auditory scene analysis. These changes are intended to open up new questions and give new perspectives on our knowledge about auditory scene analysis. In detail, the thesis established three-tone sequences as a tool for specific investigations on the perceptual foreground and background processing in complex auditory scenes. In addition, it modifies an already established approach for indirect measures of auditory perception in a way that enables detailed and univocal investigations on background processing. Finally, a new response method, namely a no-report method for auditory perception that might also serve as a method to validate subjective report measures, was developed. This new methodological approach uses eye movements as a measurement tool for auditory perception. With the aid of all these methodological improvements, the current thesis shows that auditory foreground formation is actually more complex than previously assumed since listeners hold more than one auditory source in the foreground without being forced to do so. In addition, it shows that the auditory system prefers a limited number of specific source configurations probably to avoid combinatorial explosion. Finally, the thesis indicates that the formation of the perceptual background is also quite complex since the auditory system holds perceptual organization alternatives in parallel that were basically assumed to be mutually exclusive. Thus, both the foreground and the background follow different rules than expected based on two-tone sequences. However, one finding seems to be true for both kinds of sequences: the impact of the tone pattern on the subjective perception is marginal, be it in two- or three-tone sequences. Regarding the no-report method for auditory perception, the thesis shows that eye movements and the reported auditory foreground formations were in good agreement and it seems like this approach indeed has the potential to become a first no-report measure for auditory perception.:Abstract 3 Acknowledgments 5 List of Figures 8 List of Tables 9 Collaborations 11 1 General Introduction 13 1.1 The auditory foreground 13 1.1.1 Attention and auditory scene analysis 13 1.1.2 Investigating auditory scene analysis with two-tone sequences 16 1.1.3 Multistability 18 1.2 The auditory background 21 1.2.1 Investigating auditory background processing 22 1.3 Measures of auditory perception 23 1.3.1 Report procedures 23 1.3.2 Performance-based measures 26 1.3.3 Psychophysiological measures 27 1.4 Summary and goals of the thesis 30 2 The auditory foreground 33 2.1 Study 1: Foreground formation in three-tone sequences 33 2.1.1 Abstract 33 2.1.2 Introduction 33 2.1.3 Methods 37 2.1.4 Results 43 2.1.5 Discussion 48 2.2 Study 2: Pattern effects in three-tone sequences 53 2.2.1 Abstract 53 2.2.2 Methods 53 2.2.3 Results 54 2.2.4 Discussion 58 2.3 Study 3: Pattern effects in two-tone sequences 59 2.3.1 Abstract 59 2.3.2 Introduction 59 2.3.3 General Methods 63 2.3.4 Experiment 1 – Methods and Results 65 2.3.5 Experiment 2 – Methods and Results 67 2.3.6 Experiment 3 – Methods and Results 70 2.3.7 Discussion 72 3 The auditory background 74 3.1 Study 4: Background formation in three-tone sequences 74 3.1.1 Abstract 74 3.1.2 Introduction 74 3.1.3 Methods 77 3.1.4 Results 82 3.1.5 Discussion 86 4 Audio-visual coupling for investigations on auditory perception 90 4.1 Study 5: Using Binocular Rivalry to tag auditory perception 90 4.1.1 Abstract 90 4.1.2 Introduction 90 4.1.3 Methods 92 4.1.4 Results 100 4.1.5 Discussion 108 5 General Discussion 113 5.1 Short review of the findings 113 5.2 The auditory foreground 114 5.2.1 Auditory foreground formation and attention theories 114 5.2.2 The role of tone pattern in foreground formation 116 5.2.3 Methodological considerations and continuation 117 5.3 The auditory background 118 5.3.1 Auditory object formation without attention 120 5.3.2 Multistability without attention 121 5.3.3 Methodological considerations and continuation 122 5.4 Auditory scene analysis by audio-visual coupling 124 5.4.1 Methodological considerations and continuation 124 5.5 Artificial listening situations and conclusions on natural hearing 126 6 Conclusions 128 References 130

Alerting signals often serve to reduce temporal uncertainty by predicting the time of stimulus onset. The resulting response time benefits have often been explained by facilitated translation of stimulus codes into response codes on the basis of established stimulus-response (S-R) links. In paradigms of masked S-R priming alerting signals also modulate response activation processes triggered by subliminally presented prime stimuli. In the present study we tested whether facilitation of visuo-motor translation processes due to alerting signals critically depends on established S-R links. Alerting signals resulted in significantly enhanced masked priming effects for masked prime stimuli that included and that did not include established S-R links (i.e., target vs. novel primes). Yet, the alerting-priming interaction was more pronounced for target than for novel primes. These results suggest that effects of alerting signals on masked priming are especially evident when S-R links between prime and target exist. At the same time, an alerting-priming interaction also for novel primes suggests that alerting signals also facilitate stimulus-response translation processes when masked prime stimuli provide action-trigger conditions in terms of programmed S-R links.