Photoplethysmography (PPG) is a non invasive measurement of the blood flow, that can be used instead of electrocardiography to estimate heart rate (HR). Most existing techniques used for HR monitoring in fitness with PPG focus on slowly running alone, while those suitable for intensive physical exercise need an initialization stage in which wearers are required to stand still for several seconds. This paper present a novel algorithm for HR estimation from PPG signal based on motion artifact removal (MAR) and adaptive tracking (AT) that overcomes limitations of the previous techniques. Experimental evaluations performed on datasets recorded from several subjects during running show an average absolute error of HR estimation of 2.26 beats per minute, demonstrating the validity of the presented technique to monitor HR using wearable devices which use PPG signals.

Abstract-This paper presents and compares two algorithms based on artificial neural networks (ANNs) for sound event detection in real life audio. Both systems have been developed and evaluated with the material provided for the third task of the Detection and Classification of Acoustic Scenes and Events (DCASE) 2016 challenge. For the first algorithm, we make use of an ANN trained on different features extracted from the downmixed mono channel audio. Secondly, we analyse a binaural algorithm where the same feature extraction is performed on four different channels: the two binaural channels, the averaged monaural signal and the difference between the binaural channels. The proposed feature set comprehends, along with mel-frequency cepstral coefficients and log-mel energies, also activity information extracted with two different voice activity detection (VAD) algorithms. Moreover, we will present results obtained with two different neural architectures, namely multilayer perceptrons (MLPs) and recurrent neural networks. The highest scores obtained on the DCASE 2016 evaluation dataset are achieved by a MLP trained on binaural features and adaptive energy VAD; they consist of an averaged error rate of 0.79 and an averaged F1 score of 48.1%, thus marking an improvement over the best score registered in the DCASE 2016 challenge.

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