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Thomas Sühn,1 Moritz Spiller,1 Rutuja Salvi,2 Stefan Hellwig,2 Axel Boese,1 Alfredo Illanes,1 Michael Friebe1 1INKA - Innovation Laboratory for Image Guided Therapy, Medizinische Fakultät, Otto-Von-Guericke-Universität, Magdeburg, Sachsen-Anhalt, Germany; 2IDTM GmbH, Castrop-Rauxel, Nordrhein-Westfalen, GermanyCorrespondence: Thomas Sühn Email thomas.suehn@med.ovgu.deIntroduction: Atherosclerotic diseases of the carotid are a primary cause of cerebrovascular events such as stroke. For the diagnosis and monitoring angiography, ultrasound- or magnetic resonance-based imaging is used which requires costly hardware. In contrast, the auscultation of carotid sounds and screening for bruits – audible patterns related to turbulent blood flow – is a simple examination with comparably little technical demands. It can indicate atherosclerotic diseases and justify further diagnostics but is currently subjective and examiner dependent.Methods: We propose an easy-to-use computer-assisted auscultation system for a stable and reproducible acquisition of vascular sounds of the carotid. A dedicated skin-transducer-interface was incorporated into a handheld device. The interface comprises two bell-shaped structures, one with additional acoustic membrane, to ensure defined skin contact and a stable propagation path of the sound. The device is connected wirelessly to a desktop application allowing real-time visualization, assessment of signal quality and input of supplementary information along with storage of recordings in a database. An experimental study with 5 healthy subjects was conducted to evaluate usability and stability of the device. Five recordings per carotid served as data basis for a wavelet-based analysis of the stability of spectral characteristics of the recordings.Results: The energy distribution of the wavelet-based stationary spectra proved stable for measurements of a particular carotid with the majority of the energy located between 3 and 40 Hz. Different spectral properties of the carotids of one individual indicate the presence of sound characteristics linked to the particular vessel. User-dependent parameters such as variations of the applied contact pressure appeared to have minor influence on the general stability.Conclusion: The system provides a platform for reproducible carotid auscultation and the creation of a database of pathological vascular sounds, which is a prerequisite to investigate sound-based vascular monitoring.Keywords: stenosis, screening, computer-assisted auscultation, vascular disease, bruit, long-term monitoring, heart sound

Objective 1 Introduction: The biological mechanisms underlying hyperacusis are poorly understood, but medical conditions and genetic factors associated with this disorder could provide insights on underlying causes and treatments. Human investigations suggest that chronic stress may contribute to hyperacusis, but experimental evidence for this view is limited. Material and methods: We pharmacologically induced chronic stress in rats by chronically administering corticos-terone (CORT) stress hormone in drinking water. Loudness measures were obtained by measuring rat reaction time-intensity (RT-I) functions before and after chronic CORT treatment. Results and conclusions: CORT treatment significantly reduced reaction times at suprathreshold intensities, behavioral evidence of loudness hyperacusis. Electrophysiological studies showed no change in the neural output of the cochlea in CORT-treated rats; however, sound evoked neural responses from higher auditory centers were significantly enhanced, evidence of sound-evoked neural hyperactivity in the central auditory pathway. Rats were tested for sound avoidance hyperacusis using an Active Sound Avoidance Paradigm (ASAP) in which sounds of increasing intensity were used to "drive" a rat from a preferred dark enclosure to a bright, open "avoidance" arena. Following Chronic CORT treatment, a 90 dB broadband noise was much more effective in "driving" the rat from the preferred dark enclosure into the bright, open "avoidance" arena, evidence that chronic stress had induced sound avoidance hyperacusis. Objective 2 Introduction: Many individuals with autism and autism spectrum disorder (ASD) exhibit hyperacusis. Fragile X (FX) syndrome, a leading genetic cause of ASD, is associated with CGG expansions near the Fmrl gene resulting in FMRP protein deficiency. Material and methods: We tested for loudness hyperacusis in FX syndrome by comparing RT-I loudness growth functions from male rats lacking the Fmrl gene with WT rats. Results and conclusions: Fmrl knockout and WT rats had similar thresholds in quiet, however, Fmrl knockout rats had significantly shorter reaction times at suprathreshold intensities than WT rats for pure tones and broadband noise, behavioral evidence of loudness hyperacusis in Fmrl knockout rats. Temporal integration of loudness was evaluated by measuring reaction time as a function of stimulus duration. Reaction times decreased as duration increased from 50 to 300 ms in WT rats, evidence of temporal integration of loudness. Reaction time in Fmrl knockout rats were shorter than WT rats and RTs showed little change with duration, evidence of aberrant temporal integration in Fmrl rats. The MTEP-mGlu5 receptor has been implicated in autism. To investigate its role in hyperacusis, reaction-time intensity functions were measured in Fmrl knockout rat and WT rats before and after treatment with an MTEP mGlu5 receptor antagonist. The MTEP mGlu5 receptor antagonist had no effect on the reaction times of WT rats, whereas it dose-dependently increased reaction times in Fmrl KO rats to values similar to those WT rats. These results suggest that MTEP-mGlu5 antagonists might be clinically effective at suppressing loudness hyperacusis in individuals with ASD. [ABSTRACT FROM AUTHOR]

Given a continuous-time system, a technique to directly obtain an approximate delta-operator formulated discrete-time system (Delta-system) is presented. For this purpose, the analog of the well known Boxer-Thaler integrators (q-forms) applicable to shift-operator formulated discrete-time systems (q-systems) are derived for Delta-systems. Next, using these Delta-forms, a method to obtain an approximate Delta-system of a given continuous-time system is derived. This algorithm is easily implementable in a computer with little computational burden. It is shown that, as sampling time decreases, the Delta-system thus obtained yields the given continuous-time system further verifying the close equivalence between this formulation and continuous-time systems. Two examples illustrating advantages that may be gained by utilizing these Delta-forms in digitizing analog systems are also included.

In previous work, we demonstrated the potential of blood flow sounds for biometric authentication acquired by a custom-built auscultation device. For this purpose, we calculated the frequency spectrum for each cardiac cycle represented within the measurements based on continuous wavelet transform. The resulting spectral images were used to train a convolutional neural network based on measurements from seven users. In this work, we investigate which areas of those images are relevant for the network to correctly identify a user. Since they describe the frequencies’ energy within a cardiac cycle, this information can be used to gain knowledge on biometric properties within the signal. Therefore, we calculate the saliency maps for each input image and investigate their mean for each user, opening perspectives for further investigation of the spectral information that was found to be potentially relevant.

Cerebrovascular diseases like atherosclerosis pose a great threat to health and wellbeing of people worldwide. To enable early diagnosis and treatment of a gradually progressing occlusion of the carotid arteries, we propose the BODYTUNE system. Consisting of a custom-built auscultation device and a mobile application, it aims at enabling the monitoring of the blood flow within the carotid arteries on a regular basis at home. In this work, we present the results of a survey with 65 participants from the system target group to investigate aspects like technical affinity and experience with comparable systems. These results provide the basis on how the BODYTUNE system should be designed to be user-centered, concerns.

Auscultation methods allow a non-invasive diagnosis of cardiovascular diseases like atherosclerosis based on blood flow sounds of the carotid arteries. Since this process is highly dependent on the clinician’s experience, it is of great interest to develop automated data processing techniques for objective assessment. We have recently proposed a computerassisted auscultation system that we use to acquire carotid blood flow sounds. In this work, we present an approach for detecting artifacts within the blood flow sound caused by swallowing or coughing events. For this purpose, we first decompose the signal using a discrete wavelet transform (DTW). Then, we compute an energy ratio between the DWT scales associated with the signal information with and without artifacts using a sliding window of 1 s length. Evaluation based on Kruskal-Wallis and Wilcoxon rank-sum tests shows a statistically significant difference (p-value

Auscultation methods allow the non-invasive diagnosis of pathological conditions (e.g., of the lung, heart or blood vessels) based on sounds that the body produces (e.g., breathing, heartbeat, swallowing or the blood flow). Through regular homebased examinations and Big Data combined with Machine learning techniques like Deep Learning, these could help detect diseases in an early stage, thus preventing serious health conditions and subsequently ensuring optimal therapy through continuous monitoring. This paper presents BODYTUNE, a novel inexpensive multi-auscultation system that aims at providing a tool for establishing a baseline of audio signal derived classification parameters that could be used for the self-monitoring of personal health for everybody through the analysis of deviations from that baseline. In the future, Big Data analysis could additionally lead to prediction and early detection of disease events.