Augmentation Methods on Monophonic Audio for Instrument Classification in Polyphonic Music

Instrument classification is one of the fields in Music Information Retrieval (MIR) that has attracted a lot of research interest. However, the majority of that is dealing with monophonic music, while efforts on polyphonic material mainly focus on predominant instrument recognition. In this paper, we propose an approach for instrument classification in polyphonic music from purely monophonic data, that involves performing data augmentation by mixing different audio segments. A variety of data augmentation techniques focusing on different sonic aspects, such as overlaying audio segments of the same genre, as well as pitch and tempo-based synchronization, are explored. We utilize Convolutional Neural Networks for the classification task, comparing shallow to deep network architectures. We further investigate the usage of a combination of the above classifiers, each trained on a single augmented dataset. An ensemble of VGG-like classifiers, trained on non-augmented, pitch-synchronized, tempo-synchronized and genre-similar excerpts, respectively, yields the best results, achieving slightly above 80% in terms of label ranking average precision (LRAP) in the IRMAS test set.ruments in over 2300 testing tracks

A Comprehensive Review on Audio based Musical Instrument Recognition: Human-Machine Interaction towards Industry 4.0

Over the last two decades, the application of machine technology has shifted from industrial to residential use. Further, advances in hardware and software sectors have led machine technology to its utmost application, the human-machine interaction, a multimodal communication. Multimodal communication refers to the integration of various modalities of information like speech, image, music, gesture, and facial expressions. Music is the non-verbal type of communication that humans often use to express their minds. Thus, Music Information Retrieval (MIR) has become a booming field of research and has gained a lot of interest from the academic community, music industry, and vast multimedia users. The problem in MIR is accessing and retrieving a specific type of music as demanded from the extensive music data. The most inherent problem in MIR is music classification. The essential MIR tasks are artist identification, genre classification, mood classification, music annotation, and instrument recognition. Among these, instrument recognition is a vital sub-task in MIR for various reasons, including retrieval of music information, sound source separation, and automatic music transcription. In recent past years, many researchers have reported different machine learning techniques for musical instrument recognition and proved some of them to be good ones. This article provides a systematic, comprehensive review of the advanced machine learning techniques used for musical instrument recognition. We have stressed on different audio feature descriptors of common choices of classifier learning used for musical instrument recognition. This review article emphasizes on the recent developments in music classification techniques and discusses a few associated future research problems

Análisis comparativo de los métodos REPET+ y UNet para la separación de la voz cantada en una pista musical

La separación de fuentes musicales es la tarea de aislar las frases musicales ejecutadas por diferentes instrumentos grabados individualmente y dispuestos juntos para formar una canción. A la actualidad se han desarrollados diversos métodos para abarcar la separación de fuentes musicales, los cuales se pueden clasificar en métodos supervisados y no supervisados; sin embargo, no se ha desarrollado una investigación en la cual se analice la efectividad de usar diferentes métodos en conjunto. Por este motivo, el presente trabajo busca medir los resultados de la utilización de dos métodos, REPET+ (no supervisado) y UNet (supervisado), de manera conjunta y aislada para separar las ondas musicales producidas por un cantante y las ondas provenientes de los instrumentos. Los resultados muestran un puntaje general (SDR) de los métodos para la separación vocal para la red UNet fue de 5.38 dB, REPET+ de -4.3 dB, -2.55 dB para REPET+ & UNet, y, -0.38 dB para UNet & REPET+, -6.16 dB para REPET+ & REPET+ y 5.17 dB para UNet & UNet, demostrando la superioridad de la red UNet para la separación de ondas vocales frente al método REPET+. Además, la utilización de los métodos en forma conjunta muestra una leve mejoría en ciertas métricas de evaluación; sin embargo, tomando en cuenta todas las métricas (SDR, SIR y SAR), se pone en evidencia que esto conlleva a una pérdida de información que recae en un bajo puntaje general de la solución.Music source separation is the task of isolating the musical phrases played by different instruments recorded individually and arranged together to form a song. Nowadays, several methods have been developed to cover the separation of music sources, which can be classified into supervised and unsupervised learning, however, no research has been developed in which the effectiveness of using different methods together are analyzed , that's the reason the present work seeks to measure the results of the use of two methods, REPET + (unsupervised) and UNet (supervised), jointly and in isolation to separate the music waves produced by a singer and the waves from the instruments. The results show an overall score (SDR) of the methods for vocal separation for the UNet network was 5.38 dB, REPET+ -4.3 dB, -2.55 dB for REPET+ & UNet, -0.38 dB for UNet & REPET+, -6.16 dB for REPET+ & REPET+ and 5.17 dB for UNet & UNet, demonstrating the superiority of the UNet network for the separation of vocal waves compared to the REPET+ method. In addition, the use of the methods together shows a slight improvement in certain evaluation metrics, however, considering all the metrics (SDR, SIR and SAR), it is evident that this leads to a loss of information that results in a low overall score of the solution

Automatic music transcription: challenges and future directions

Automatic music transcription is considered by many to be a key enabling technology in music signal processing. However, the performance of transcription systems is still significantly below that of a human expert, and accuracies reported in recent years seem to have reached a limit, although the field is still very active. In this paper we analyse limitations of current methods and identify promising directions for future research. Current transcription methods use general purpose models which are unable to capture the rich diversity found in music signals. One way to overcome the limited performance of transcription systems is to tailor algorithms to specific use-cases. Semi-automatic approaches are another way of achieving a more reliable transcription. Also, the wealth of musical scores and corresponding audio data now available are a rich potential source of training data, via forced alignment of audio to scores, but large scale utilisation of such data has yet to be attempted. Other promising approaches include the integration of information from multiple algorithms and different musical aspects

Applying source separation to music

International audienceSeparation of existing audio into remixable elements is very useful to repurpose music audio. Applications include upmixing video soundtracks to surround sound (e.g. home theater 5.1 systems), facilitating music transcriptions, allowing better mashups and remixes for disk jockeys, and rebalancing sound levels on multiple instruments or voices recorded simultaneously to a single track. In this chapter, we provide an overview of the algorithms and approaches designed to address the challenges and opportunities in music. Where applicable, we also introduce commonalities and links to source separation for video soundtracks, since many musical scenarios involve video soundtracks (e.g. YouTube recordings of live concerts, movie sound tracks). While space prohibits describing every method in detail, we include detail on representative music‐specific algorithms and approaches not covered in other chapters. The intent is to give the reader a high‐level understanding of the workings of key exemplars of the source separation approaches applied in this domain

Semi-supervised musical instrument recognition

The application areas of music information retrieval have been gaining popularity over the last decades. Musical instrument recognition is an example of a specific research topic in the field. In this thesis, semi-supervised learning techniques are explored in the context of musical instrument recognition. The conventional approaches employed for musical instrument recognition rely on annotated data, i.e., example recordings of the target instruments with associated information about the target labels in order to perform training. This implies a highly laborious and tedious work of manually annotating the collected training data. The semi-supervised methods enable incorporating additional unannotated data into training. Such data consists of merely the recordings of the instruments and is therefore significantly easier to acquire. Hence, these methods allow keeping the overall development cost at the same level while notably improving the performance of a system. The implemented musical instrument recognition system utilises the mixture model semi-supervised learning scheme in the form of two EM-based algorithms. Furthermore, upgraded versions, namely, the additional labelled data weighting and class-wise retraining, for the improved performance and convergence criteria in terms of the particular classification scenario are proposed. The evaluation is performed on sets consisting of four and ten instruments and yields the overall average recognition accuracy rates of 95.3 and 68.4%, respectively. These correspond to the absolute gains of 6.1 and 9.7% compared to the initial, purely supervised cases. Additional experiments are conducted in terms of the effects of the proposed modifications, as well as the investigation of the optimal relative labelled dataset size. In general, the obtained performance improvement is quite noteworthy, and future research directions suggest to subsequently investigate the behaviour of the implemented algorithms along with the proposed and further extended approaches

Singing Voice Recognition for Music Information Retrieval

This thesis proposes signal processing methods for analysis of singing voice audio signals, with the objectives of obtaining information about the identity and lyrics content of the singing. Two main topics are presented, singer identification in monophonic and polyphonic music, and lyrics transcription and alignment. The information automatically extracted from the singing voice is meant to be used for applications such as music classification, sorting and organizing music databases, music information retrieval, etc. For singer identification, the thesis introduces methods from general audio classification and specific methods for dealing with the presence of accompaniment. The emphasis is on singer identification in polyphonic audio, where the singing voice is present along with musical accompaniment. The presence of instruments is detrimental to voice identification performance, and eliminating the effect of instrumental accompaniment is an important aspect of the problem. The study of singer identification is centered around the degradation of classification performance in presence of instruments, and separation of the vocal line for improving performance. For the study, monophonic singing was mixed with instrumental accompaniment at different signal-to-noise (singing-to-accompaniment) ratios and the classification process was performed on the polyphonic mixture and on the vocal line separated from the polyphonic mixture. The method for classification including the step for separating the vocals is improving significantly the performance compared to classification of the polyphonic mixtures, but not close to the performance in classifying the monophonic singing itself. Nevertheless, the results show that classification of singing voices can be done robustly in polyphonic music when using source separation. In the problem of lyrics transcription, the thesis introduces the general speech recognition framework and various adjustments that can be done before applying the methods on singing voice. The variability of phonation in singing poses a significant challenge to the speech recognition approach. The thesis proposes using phoneme models trained on speech data and adapted to singing voice characteristics for the recognition of phonemes and words from a singing voice signal. Language models and adaptation techniques are an important aspect of the recognition process. There are two different ways of recognizing the phonemes in the audio: one is alignment, when the true transcription is known and the phonemes have to be located, other one is recognition, when both transcription and location of phonemes have to be found. The alignment is, obviously, a simplified form of the recognition task. Alignment of textual lyrics to music audio is performed by aligning the phonetic transcription of the lyrics with the vocal line separated from the polyphonic mixture, using a collection of commercial songs. The word recognition is tested for transcription of lyrics from monophonic singing. The performance of the proposed system for automatic alignment of lyrics and audio is sufficient for facilitating applications such as automatic karaoke annotation or song browsing. The word recognition accuracy of the lyrics transcription from singing is quite low, but it is shown to be useful in a query-by-singing application, for performing a textual search based on the words recognized from the query. When some key words in the query are recognized, the song can be reliably identified

From heuristics-based to data-driven audio melody extraction

The identification of the melody from a music recording is a relatively easy task for humans, but very challenging for computational systems. This task is known as "audio melody extraction", more formally defined as the automatic estimation of the pitch sequence of the melody directly from the audio signal of a polyphonic music recording. This thesis investigates the benefits of exploiting knowledge automatically derived from data for audio melody extraction, by combining digital signal processing and machine learning methods. We extend the scope of melody extraction research by working with a varied dataset and multiple definitions of melody. We first present an overview of the state of the art, and perform an evaluation focused on a novel symphonic music dataset. We then propose melody extraction methods based on a source-filter model and pitch contour characterisation and evaluate them on a wide range of music genres. Finally, we explore novel timbre, tonal and spatial features for contour characterisation, and propose a method for estimating multiple melodic lines. The combination of supervised and unsupervised approaches leads to advancements on melody extraction and shows a promising path for future research and applications