Towards the tangible: microtonal scale exploration in Central-African music

This proposal presents TARSOS, an easy-to-use platform for automated pitch analysis especially designed to explore non-Western music. Two considerations were the starting point of this research: i) thnomusicology is mainly performed from an anthropological and ethnographical approach, and ii) current Music Information Retrieval (MIR) applications are biased towards Western music and are thus not suitable to the particularities of other musical cultures. This research tries to develop an unbiased approach by a flexible interface for detection and representation of tone scales. No predispositions towards a certain music theory or pitch organization are made. Our goal is to document an aspect of the endangered musical heritage of African oral cultures, namely tone scale diversity

Panako: a scalable acoustic fingerprinting system handling time-scale and pitch modification

In this paper a scalable granular acoustic fingerprinting system robust against time and pitch scale modification is presented. The aim of acoustic fingerprinting is to identify identical, or recognize similar, audio fragments in a large set using condensed representations of audio signals, i.e. fingerprints. A robust fingerprinting system generates similar fingerprints for perceptually similar audio signals. The new system, presented here, handles a variety of distortions well. It is designed to be robust against pitch shifting, time stretching and tempo changes, while remaining scalable. After a query, the system returns the start time in the reference audio, and the amount of pitch shift and tempo change that has been applied. The design of the system that offers this unique combination of features is the main contribution of this research. The fingerprint itself consists of a combination of key points in a Constant-Q spectrogram. The system is evaluated on commodity hardware using a freely available reference database with fingerprints of over 30.000 songs. The results show that the system responds quickly and reliably on queries, while handling time and pitch scale modifications of up to ten percent

Engineering systematic musicology : methods and services for computational and empirical music research

One of the main research questions of *systematic musicology* is concerned with how people make sense of their musical environment. It is concerned with signification and meaning-formation and relates musical structures to effects of music. These fundamental aspects can be approached from many different directions. One could take a cultural perspective where music is considered a phenomenon of human expression, firmly embedded in tradition. Another approach would be a cognitive perspective, where music is considered as an acoustical signal of which perception involves categorizations linked to representations and learning. A performance perspective where music is the outcome of human interaction is also an equally valid view. To understand a phenomenon combining multiple perspectives often makes sense. The methods employed within each of these approaches turn questions into concrete musicological research projects. It is safe to say that today many of these methods draw upon digital data and tools. Some of those general methods are feature extraction from audio and movement signals, machine learning, classification and statistics. However, the problem is that, very often, the *empirical and computational methods require technical solutions* beyond the skills of researchers that typically have a humanities background. At that point, these researchers need access to specialized technical knowledge to advance their research. My PhD-work should be seen within the context of that tradition. In many respects I adopt a problem-solving attitude to problems that are posed by research in systematic musicology. This work *explores solutions that are relevant for systematic musicology*. It does this by engineering solutions for measurement problems in empirical research and developing research software which facilitates computational research. These solutions are placed in an engineering-humanities plane. The first axis of the plane contrasts *services* with *methods*. Methods *in* systematic musicology propose ways to generate new insights in music related phenomena or contribute to how research can be done. Services *for* systematic musicology, on the other hand, support or automate research tasks which allow to change the scope of research. A shift in scope allows researchers to cope with larger data sets which offers a broader view on the phenomenon. The second axis indicates how important Music Information Retrieval (MIR) techniques are in a solution. MIR-techniques are contrasted with various techniques to support empirical research. My research resulted in a total of thirteen solutions which are placed in this plane. The description of seven of these are bundled in this dissertation. Three fall into the methods category and four in the services category. For example Tarsos presents a method to compare performance practice with theoretical scales on a large scale. SyncSink is an example of a service

OLAF : Overly Lightweight Acoustic Fingerprinting

Olaf is a portable, landmark-based, acoustic fingerprint-ing system released as open source software. Olaf runs on embedded platforms, traditional computers and in the browser. Olaf is able to extract fingerprints from an audio stream, and either store those fingerprints in a database, or find a match between extracted fingerprints and stored fingerprints. It implements an algorithm similar to the one described in a classic ISMIR paper and has similar retrieval performance. It facilitates the many use cases acoustic fingerprinting has to offer such as duplicate detection, meta-data coupling, and synchronization

A Robust Audio Fingerprinter Based on Pitch Class Histograms Applications for Ethnic Music Archives

In this paper we present a new acoustic fingerprinting system, based on pitch class histograms. The aim of acoustic fingerprinting is to generate a small representation of an audio signal that can be used to identify identical, or recognize similar, audio snippets in a large audio set. A robust fingerprinting system generates similar fingerprints for perceptually similar audio signals. A piece of music with a noise added should generate an almost identical fingerprint as the original. The new system, presented here, has some interesting features which makes it a valuable tool to manage ethnic music archives: the fingerprints are rather robust against pitch shift, tempo changes, several synthetic audio effects, and reversal of the audio. When only part of the audio is used to generate a fingerprint, the system keeps working but retrieval performance degrades

Sound to scale to sound, a setup for microtonal exploration and composition

This paper elaborates on a setup for microtonal exploration, experimentation and composition. Where the initial design of the software Tarsos aimed for the scale analysis of ethnic music recordings, it turned out to deliver a flexible platform for pitch exploration of any kind of music. Scales from ethnic music, but also theoretically designed scales and scales from musical practice, can be analyzed in great detail and can be adapted by a flexible interface with auditory feedback. The output, the scales, are written into the standardized Scala format, and can be used in a MIDI-to-WAV converter that renders a MIDI file into audio tuned using the scale. This setup creates an environment for tone scale exploration that can be used for microtonal composition

Automatic comparison of global children’s and adult songs supports a sensorimotor hypothesis for the origin of musical scales

Music throughout the world varies greatly, yet some musical features like scale structure display striking crosscultural similarities. Are there musical laws or biological constraints that underlie this diversity? The “vocal mistuning” hypothesis proposes that cross-cultural regularities in musical scales arise from imprecision in vocal tuning, while the integer-ratio hypothesis proposes that they arise from perceptual principles based on psychoacoustic consonance. In order to test these hypotheses, we conducted automatic comparative analysis of 100 children’s and adult songs from throughout the world. We found that children’s songs tend to have narrower melodic range, fewer scale degrees, and less precise intonation than adult songs, consistent with motor limitations due to their earlier developmental stage. On the other hand, adult and children’s songs share some common tuning intervals at small-integer ratios, particularly the perfect 5th (~3:2 ratio). These results suggest that some widespread aspects of musical scales may be caused by motor constraints, but also suggest that perceptual preferences for simple integer ratios might contribute to cross-cultural regularities in scale structure. We propose a “sensorimotor hypothesis” to unify these competing theories