Adaptive Frequency Neural Networks for Dynamic Pulse and Metre Perception.

Beat induction, the means by which humans listen to music and perceive a steady pulse, is achieved via a perceptualand cognitive process. Computationally modelling this phenomenon is an open problem, especially when processing expressive shaping of the music such as tempo change.To meet this challenge we propose Adaptive Frequency Neural Networks (AFNNs), an extension of Gradient Frequency Neural Networks (GFNNs).GFNNs are based on neurodynamic models and have been applied successfully to a range of difficult music perception problems including those with syncopated and polyrhythmic stimuli. AFNNs extend GFNNs by applying a Hebbian learning rule to the oscillator frequencies. Thus the frequencies in an AFNN adapt to the stimulus through an attraction to local areas of resonance, and allow for a great dimensionality reduction in the network.Where previous work with GFNNs has focused on frequency and amplitude responses, we also consider phase information as critical for pulse perception. Evaluating the time-based output, we find significantly improved re-sponses of AFNNs compared to GFNNs to stimuli with both steady and varying pulse frequencies. This leads us to believe that AFNNs could replace the linear filtering methods commonly used in beat tracking and tempo estimationsystems, and lead to more accurate methods

The influence of external and internal motor processes on human auditory rhythm perception

Musical rhythm is composed of organized temporal patterns, and the processes underlying rhythm perception are found to engage both auditory and motor systems. Despite behavioral and neuroscience evidence converging to this audio-motor interaction, relatively little is known about the effect of specific motor processes on auditory rhythm perception. This doctoral thesis was devoted to investigating the influence of both external and internal motor processes on the way we perceive an auditory rhythm. The first half of the thesis intended to establish whether overt body movement had a facilitatory effect on our ability to perceive the auditory rhythmic structure, and whether this effect was modulated by musical training. To this end, musicians and non-musicians performed a pulse-finding task either using natural body movement or through listening only, and produced their identified pulse by finger tapping. The results showed that overt movement benefited rhythm (pulse) perception especially for non-musicians, confirming the facilitatory role of external motor activities in hearing the rhythm, as well as its interaction with musical training. The second half of the thesis tested the idea that indirect, covert motor input, such as that transformed from the visual stimuli, could influence our perceived structure of an auditory rhythm. Three experiments examined the subjectively perceived tempo of an auditory sequence under different visual motion stimulations, while the auditory and visual streams were presented independently of each other. The results revealed that the perceived auditory tempo was accordingly influenced by the concurrent visual motion conditions, and the effect was related to the increment or decrement of visual motion speed. This supported the hypothesis that the internal motor information extracted from the visuomotor stimulation could be incorporated into the percept of an auditory rhythm. Taken together, the present thesis concludes that, rather than as a mere reaction to the given auditory input, our motor system plays an important role in contributing to the perceptual process of the auditory rhythm. This can occur via both external and internal motor activities, and may not only influence how we hear a rhythm but also under some circumstances improve our ability to hear the rhythm.Musikalische Rhythmen bestehen aus zeitlich strukturierten Mustern akustischer Stimuli. Es konnte gezeigt werden, dass die Prozesse, welche der Rhythmuswahrnehmung zugrunde liegen, sowohl motorische als auch auditive Systeme nutzen. Obwohl sich für diese auditiv-motorischen Interaktionen sowohl in den Verhaltenswissenschaften als auch Neurowissenschaften übereinstimmende Belege finden, weiß man bislang relativ wenig über die Auswirkungen spezifischer motorischer Prozesse auf die auditive Rhythmuswahrnehmung. Diese Doktorarbeit untersucht den Einfluss externaler und internaler motorischer Prozesse auf die Art und Weise, wie auditive Rhythmen wahrgenommen werden. Der erste Teil der Arbeit diente dem Ziel herauszufinden, ob körperliche Bewegungen es dem Gehirn erleichtern können, die Struktur von auditiven Rhythmen zu erkennen, und, wenn ja, ob dieser Effekt durch ein musikalisches Training beeinflusst wird. Um dies herauszufinden wurde Musikern und Nichtmusikern die Aufgabe gegeben, innerhalb von präsentierten auditiven Stimuli den Puls zu finden, wobei ein Teil der Probanden währenddessen Körperbewegungen ausführen sollte und der andere Teil nur zuhören sollte. Anschließend sollten die Probanden den gefundenen Puls durch Finger-Tapping ausführen, wobei die Reizgaben sowie die Reaktionen mittels eines computerisierten Systems kontrolliert wurden. Die Ergebnisse zeigen, dass offen ausgeführte Bewegungen die Wahrnehmung des Pulses vor allem bei Nichtmusikern verbesserten. Diese Ergebnisse bestätigen, dass Bewegungen beim Hören von Rhythmen unterstützend wirken. Außerdem zeigte sich, dass hier eine Wechselwirkung mit dem musikalischen Training besteht. Der zweite Teil der Doktorarbeit überprüfte die Idee, dass indirekte, verdeckte Bewegungsinformationen, wie sie z.B. in visuellen Stimuli enthalten sind, die wahrgenommene Struktur von auditiven Rhythmen beeinflussen können. Drei Experimente untersuchten, inwiefern das subjektiv wahrgenommene Tempo einer akustischen Sequenz durch die Präsentation unterschiedlicher visueller Bewegungsreize beeinflusst wird, wobei die akustischen und optischen Stimuli unabhängig voneinander präsentiert wurden. Die Ergebnisse zeigten, dass das wahrgenommene auditive Tempo durch die visuellen Bewegungsinformationen beeinflusst wird, und dass der Effekt in Verbindung mit der Zunahme oder Abnahme der visuellen Geschwindigkeit steht. Dies unterstützt die Hypothese, dass internale Bewegungsinformationen, welche aus visuomotorischen Reizen extrahiert werden, in die Wahrnehmung eines auditiven Rhythmus integriert werden können. Zusammen genommen, 5 zeigt die vorgestellte Arbeit, dass unser motorisches System eine wichtige Rolle im Wahrnehmungsprozess von auditiven Rhythmen spielt. Dies kann sowohl durch äußere als auch durch internale motorische Aktivitäten geschehen, und beeinflusst nicht nur die Art, wie wir Rhythmen hören, sondern verbessert unter bestimmten Bedingungen auch unsere Fähigkeit Rhythmen zu identifizieren

Deep Learning for Audio Signal Processing

Given the recent surge in developments of deep learning, this article provides a review of the state-of-the-art deep learning techniques for audio signal processing. Speech, music, and environmental sound processing are considered side-by-side, in order to point out similarities and differences between the domains, highlighting general methods, problems, key references, and potential for cross-fertilization between areas. The dominant feature representations (in particular, log-mel spectra and raw waveform) and deep learning models are reviewed, including convolutional neural networks, variants of the long short-term memory architecture, as well as more audio-specific neural network models. Subsequently, prominent deep learning application areas are covered, i.e. audio recognition (automatic speech recognition, music information retrieval, environmental sound detection, localization and tracking) and synthesis and transformation (source separation, audio enhancement, generative models for speech, sound, and music synthesis). Finally, key issues and future questions regarding deep learning applied to audio signal processing are identified.Comment: 15 pages, 2 pdf figure

Adaptive Resonance Theory: Self-Organizing Networks for Stable Learning, Recognition, and Prediction

Adaptive Resonance Theory (ART) is a neural theory of human and primate information processing and of adaptive pattern recognition and prediction for technology. Biological applications to attentive learning of visual recognition categories by inferotemporal cortex and hippocampal system, medial temporal amnesia, corticogeniculate synchronization, auditory streaming, speech recognition, and eye movement control are noted. ARTMAP systems for technology integrate neural networks, fuzzy logic, and expert production systems to carry out both unsupervised and supervised learning. Fast and slow learning are both stable response to large non stationary databases. Match tracking search conjointly maximizes learned compression while minimizing predictive error. Spatial and temporal evidence accumulation improve accuracy in 3-D object recognition. Other applications are noted.Office of Naval Research (N00014-95-I-0657, N00014-95-1-0409, N00014-92-J-1309, N00014-92-J4015); National Science Foundation (IRI-94-1659

Wearable Haptic Devices for Gait Re-education by Rhythmic Haptic Cueing

This research explores the development and evaluation of wearable haptic devices for gait sensing and rhythmic haptic cueing in the context of gait re-education for people with neurological and neurodegenerative conditions. Many people with long-term neurological and neurodegenerative conditions such as Stroke, Brain Injury, Multiple Sclerosis or Parkinson’s disease suffer from impaired walking gait pattern. Gait improvement can lead to better fluidity in walking, improved health outcomes, greater independence, and enhanced quality of life. Existing lab-based studies with wearable devices have shown that rhythmic haptic cueing can cause immediate improvements to gait features such as temporal symmetry, stride length, and walking speed. However, current wearable systems are unsuitable for self-managed use for in-the-wild applications with people having such conditions. This work aims to investigate the research question of how wearable haptic devices can help in long-term gait re-education using rhythmic haptic cueing. A longitudinal pilot study has been conducted with a brain trauma survivor, providing rhythmic haptic cueing using a wearable haptic device as a therapeutic intervention for a two-week period. Preliminary results comparing pre and post-intervention gait measurements have shown improvements in walking speed, temporal asymmetry, and stride length. The pilot study has raised an array of issues that require further study. This work aims to develop and evaluate prototype systems through an iterative design process to make possible the self-managed use of such devices in-the-wild. These systems will directly provide therapeutic intervention for gait re-education, offer enhanced information for therapists, remotely monitor dosage adherence and inform treatment and prognoses over the long-term. This research will evaluate the use of technology from the perspective of multiple stakeholders, including clinicians, carers and patients. This work has the potential to impact clinical practice nationwide and worldwide in neuro-physiotherapy

Acetylcholine neuromodulation in normal and abnormal learning and memory: vigilance control in waking, sleep, autism, amnesia, and Alzheimer's disease

This article provides a unified mechanistic neural explanation of how learning, recognition, and cognition break down during Alzheimer's disease, medial temporal amnesia, and autism. It also clarifies whey there are often sleep disturbances during these disorders. A key mechanism is how acetylcholine modules vigilance control in cortical layer