Sound predictability as a higher-order cue in auditory scene analysis

A major challenge for the auditory system is to disentangle signals emitted by two or more sound sources that are active in a temporally interleaved manner (sequential stream segregation). Besides distinct characteristics of the individual signals (e.g., their timbre, location, and pitch), one important cue for distinguishing the sound sources is how their emitted signals unfold over time. It seems intuitively plausible that signals that unfold predictably with respect to their acoustic features and time-points of occurrence, such as the repetitive signature of a train moving on the rails, can be more readily identified as originating from one sound source. Based on this rationale, predictive elements have successfully been incorporated into computational models of auditory scene analysis for many years

Identifying the Burdens and Opportunities for Tribes and Communities in Federal Facility Cleanup Activities: Environmental Remediation Technology Assessment Matrix For Tribal and Community Decision-Makers

The cleanup of this country's federal facilities can affect a wide range of tribal and community interests and concerns. The technologies now in use, or being proposed by the Department of Energy, Department of Defense and other federal agencies can affect tribal treaty protected fishing, hunting and other rights, affect air and water quality thereby requiring the tribe to bear the burden of increased environmental regulation. The International Institute for Indigenous Resource Management developed a tribal and community decision-maker's Environmental Remediation Technology Assessment Matrix that will permit tribes and communities to array technical information about environmental remediation technologies against a backdrop of tribal and community environmental, health and safety, cultural, religious, treaty and other concerns and interests. Ultimately, the matrix will allow tribes and communities to assess the impact of proposed technologies on the wide range of tribal and community interests and will promote more informed participation in federal facility cleanup activities

Perceptual bistability in auditory streaming: how much do stimulus features matter?

The auditory two-tone streaming paradigm has been used extensively to study the mechanisms that underlie the decomposition of the auditory input into coherent sound sequences. Using longer tone sequences than usual in the literature, we show that listeners hold their first percept of the sound se¬quence for a relatively long period, after which perception switches between two or more alternative sound organizations, each held on average for a much shorter duration. The first percept also differs from subsequent ones in that stimulus parameters influence its quality and duration to a far greater degree than the subsequent ones. We propose an account of auditory streaming in terms of rivalry be¬tween competing temporal associations based on two sets of processes. The formation of associations (discovery of alternative interpretations) mainly affects the first percept by determining which sound group is discovered first and how long it takes for alternative groups to be established. In contrast, sub¬sequent percepts arise from stochastic switching between the alternatives, the dynamics of which are determined by competitive interactions between the set of coexisting interpretations

Modulation-frequency acts as a primary cue for auditory stream segregation

In our surrounding acoustic world sounds are produced by different sources and interfere with each other before arriving to the ears. A key function of the auditory system is to provide consistent and robust descriptions of the coherent sound groupings and sequences (auditory objects), which likely correspond to the various sound sources in the environment. This function has been termed auditory stream segregation. In the current study we tested the effects of separation in the frequency of amplitude modulation on the segregation of concurrent sound sequences in the auditory stream-segregation paradigm (van Noorden 1975). The aim of the study was to assess 1) whether differential amplitude modulation would help in separating concurrent sound sequences and 2) whether this cue would interact with previously studied static cues (carrier frequency and location difference) in segregating concurrent streams of sound. We found that amplitude modulation difference is utilized as a primary cue for the stream segregation and it interacts with other primary cues such as frequency and location difference

Different roles of similarity and predictability in auditory stream segregation

Sound sources often emit trains of discrete sounds, such as a series of footsteps. Previously, two dif¬ferent principles have been suggested for how the human auditory system binds discrete sounds to¬gether into perceptual units. The feature similarity principle is based on linking sounds with similar characteristics over time. The predictability principle is based on linking sounds that follow each other in a predictable manner. The present study compared the effects of these two principles. Participants were presented with tone sequences and instructed to continuously indicate whether they perceived a single coherent sequence or two concurrent streams of sound. We investigated the influence of separate manipulations of similarity and predictability on these perceptual reports. Both grouping principles affected perception of the tone sequences, albeit with different characteristics. In particular, results suggest that whereas predictability is only analyzed for the currently perceived sound organization, feature similarity is also analyzed for alternative groupings of sound. Moreover, changing similarity or predictability within an ongoing sound sequence led to markedly different dynamic effects. Taken together, these results provide evidence for different roles of similarity and predictability in auditory scene analysis, suggesting that forming auditory stream representations and competition between alter¬natives rely on partly different processes

Modeling the auditory scene: predictive regularity representations and perceptual objects

Predictive processing of information is essential for goal directed behavior. We offer an account of auditory perception suggesting that representations of predictable patterns, or ‘regularities’, extracted from the incoming sounds serve as auditory perceptual objects. The auditory system continuously searches for regularities within the acoustic signal. Primitive regularities may be encoded by neurons adapting their response to specific sounds. Such neurons have been observed in many parts of the auditory system. Representations of the detected regularities produce predictions of upcoming sounds as well as alternative solutions for parsing the composite input into coherent sequences potentially emitted by putative sound sources. Accuracy of the predictions can be utilized for selecting the most likely interpretation of the auditory input. Thus in our view, perception generates hypotheses about the causal structure of the world

Feature predictability flexibly supports auditory stream segregation or integration

Many sound sources emit series of discrete sounds. Auditory perception must bind these sounds together (stream integration) while separating them from sounds emitted by other sources (stream segregation). One cue for identifying successive sounds that belong together is the predictability between their feature values. Previous studies have demonstrated that independent predictable patterns appearing separately in two interleaved sound sequences support perceptual segregation. The converse case, whether a joint predictable pattern in a mixture of interleaved sequences supports perceptual integration, has not yet been put to a rigorous empirical test. This was mainly due to difficulties in manipulating the predictability of the full sequence independently of the predictability of the interleaved subsequences. The present study implemented such an independent manipulation. Listeners continuously indicated whether they perceived a tone sequence as integrated or segregated, while predictable patterns set up to support one or the other percept were manipulated without the participants’ knowledge. Perceptual reports demonstrate that predictability supports stream segregation or integration depending on the type of predictable pattern that is present in the sequence. The effects of predictability were so pronounced as to qualitatively flip perception from predominantly (62%) integrated to predominantly (73%) segregated. These results suggest that auditory perception flexibly responds to encountered regular patterns, favoring predictable perceptual organizations over unpredictable ones. Besides underlining the role of predictability as a cue within auditory scene analysis, the present design also provides a general framework that accommodates previous investigations focusing on sub-comparisons within the present set of experimental manipulations. Results of intermediate conditions shed light on why some previous studies have obtained little to no effects of predictability on auditory scene analysis

Assessing the validity of subjective reports in the auditory streaming paradigm

Here, we tested three possible biasing effects on perceptual reports in the auditory streaming paradigm: errors due to imperfect understanding of the instructions, voluntary perceptual biasing, and susceptibility to implicit expectations. 1) Analysis of the responses to catch trials separately promoting each of the possible percepts allowed us to exclude participants who likely have not fully understood the instructions. 2) Explicit biasing instructions led to markedly different behavior than the conventional neutral-instruction condition, suggesting that listeners did not voluntarily bias their perception in a systematic way under the neutral instructions. Comparison with a random response condition further supported this conclusion. 3) No significant relationship was found between social desirability, a scale-based measure of susceptibility to implicit social expectations, and any of the perceptual measures extracted from the subjective reports. This suggests that listeners did not significantly bias their perceptual reports due to possible implicit expectations present in the experimental context. In sum, these results suggest that valid perceptual data can be obtained from subjective reports in the auditory streaming paradigm

Understanding the implementation and adoption of an information technology intervention to support medicine optimisation in primary care: qualitative study using strong structuration theory

Objectives: Using strong structuration theory, we aimed to understand the adoption and implementation of an electronic clinical audit and feedback tool to support medicine optimisation for patients in primary care. Design: This is a qualitative study informed by strong structuration theory. The analysis was thematic, using a template approach. An a priori set of thematic codes, based on strong structuration theory, was developed from the literature and applied to the transcripts. The coding template was then modified through successive readings of the data. Setting: Clinical commissioning group in the south of England. Participants: Four focus groups and five semi-structured interviews were conducted with 18 participants purposively sampled from a range of stakeholder groups (general practitioners, pharmacists, patients and commissioners). Results: Using the system could lead to improved medication safety, but use was determined by broad institutional contexts; by the perceptions, dispositions and skills of users; and by the structures embedded within the technology. These included perceptions of the system as new and requiring technical competence and skill; the adoption of the system for information gathering; and interactions and relationships that involved individual, shared or collective use. The dynamics between these external, internal and technological structures affected the adoption and implementation of the system. Conclusions: Successful implementation of information technology interventions for medicine optimisation will depend on a combination of the infrastructure within primary care, social structures embedded in the technology and the conventions, norms and dispositions of those utilising it. Future interventions, using electronic audit and feedback tools to improve medication safety, should consider the complexity of the social and organisational contexts and how internal and external structures can affect the use of the technology in order to support effective implementation

Antimicrobial activity of the essential oils of Dittrichia viscosa subsp viscosa on Helicobacter pylori

Dittrichia viscosa subsp. viscosa (Compositae) is found on edges, wood clearings and in waste places of the Iberian Peninsula. Aerial parts of D. viscosa were collected at flowering phase in September-October 2001 around Lisbon, Portugal and the essential oils isolated by hydro-distillation for 4 h using a Clevenger-type apparatus. The oils were analyzed by gas chromatography and gas chromatography-mass spectrometry. Preliminary examination of the essential oils allowed the identification of 32 components. Only four components reached percentages over 5%: fokienol (11.8%), T-muurorol (7.9%), (E)-nerolidol (5.5%) and delta-cadinene (5.0%). The essential oils were tested against Helicobacterpylori and Listeria monocytogenes. Essential oils did not have antimicrobial activity against L. monocytogenes. The essential oil at 0.88 to 22.22 mu g.ml(-1) did not inhibit the growth of H. pylori, affected the growth slightly at 44.40 mu g.ml(-1), and completely inhibited the growth at 88.80 to 133.20 mu g.ml(-1) Results show that use of D. viscosa essential oil in the treatment of gastric disorders caused by H. pylori can be effective