The goal of automatic music transcription (AMT) is to obtain a high-level symbolic representation of the notes played in a given audio recording. Despite being researched for several decades, current methods are still inadequate for many applications. To boost the accuracy in a music tutoring scenario, we exploit that the score to be played is specified and we only need to detect the differences to the actual performance. In contrast to previous work that uses score information for postprocessing, we employ the score to construct a transcription method that is tailored to the given audio recording. By adapting a score-informed dictionary learning technique as used for source separation, we learn for each score pitch a spectral pattern describing the energy distribution of associated notes in the recording. In this paper, we identify several systematic weaknesses in our previous approach and introduce three extensions to improve its performance. First, we extend our dictionary of spectral templates to a dictionary of variable-length spectrotemporal patterns. Second, we integrate the score information using soft rather than hard constraints, to better take into account that differences from the score indeed occur. Third, we introduce new regularizers to guide the learning process. Our experiments show that these extensions particularly improve the accuracy for identifying extra notes, while the accuracy for correct and missing notes remains at a similar level. The influence of each extension is demonstrated with further experiments.

The goal of music alignment is to map each temporal position in one version of a piece of music to the corresponding positions in other versions of the same piece. Despite considerable improvements in recent years, state-of-the-art methods still often fail to identify a correct alignment if versions differ substantially with respect to acoustic conditions or musical interpretation. To increase the robustness for these cases, we exploit in this work the availability of multiple versions of the piece to be aligned. By processing these jointly, we can supply the alignment process with additional examples of how a section might be interpreted or which acoustic conditions may arise. This way, we can use alignment information between two versions transitively to stabilize the alignment with a third version. Extending our previous work [1], we present two such joint alignment methods, progressive alignment and probabilistic profile, and discuss their fundamental differences and similarities on an algorithmic level. Our systematic experiments using 376 recordings of 9 pieces demonstrate that both methods can indeed improve the alignment accuracy and robustness over comparable pairwise methods. Further, we provide an in-depth analysis of the behavior of both joint alignment methods, studying the influence of parameters such as the number of performances available, comparing their computational costs, and investigating further strategies to increase both.

The goal of score-performance synchronisation is to align a given musical score to an audio recording of a performance of the same piece. A major challenge in computing such alignments is to account for musical parameters including the local tempo or playing style. To increase the overall robustness, current methods assume that notes occurring simultaneously in the score are played concurrently in a performance. Musical voices such as the melody, however, are often played asynchronously to other voices, which can lead to significant local alignment errors. In this paper, we present a novel method that handles asynchronies between the melody and the accompaniment by treating the voices as separate time lines in a multi-dimensional variant of dynamic time warping (DTW). Constraining the alignment with information obtained via classical DTW, our method measurably improves the alignment accuracy for pieces with asynchronous voices and preserves the accuracy otherwise.

This paper proposes a multichannel medium access control (MAC) protocol for energy efficient IEEE802.15.4 home area networks that consists of novel allocation and superframe scheduling algorithm that improves the channel selection strategy and the superframe scheduling. It aims to improve the overall reliability and reduce the average delay. The proposed protocol is implemented in IEEE802.15.4 home area network andsimulation results show the proposed protocol outperforms the existing IEEE802.15.4 MAC protocols in the aspects of schedulability, reliability, delay and the overall throughput.