Download On the Definition of Musical Notes from Pitch Tracks for Melody Detection in Polyphonic Recordings
The present study addresses the problem of defining musical notes from pitch tracks, in the context of a system for melody detection in polyphonic musical signals. This is an important issue for melody transcription, as well as melody-based music information retrieval. Previous work in the area tackled mainly the extraction of melodic pitch lines, without explicit determination of musical notes. Therefore, in this paper we propose an approach for the creation of musical notes based on a two-stage segmentation of pitch tracks. In the first step, frequency-based segmentation is carried out through the detection of frequency variations in pitch tracks. In the second stage, salience-based segmentation is performed so as to split consecutive notes with equal value, by making use of salience minima and note onsets.
Download Finding intensities and temporal characteristics in piano music
Timing and dynamics are two important factors in music performance. Research on dynamics-related issues is comparatively rare because data on dynamics is difficult to obtain from music performance. Nevertheless, research of this kind is vital to the understanding of music performance and here we are investigating ways to identify the intensities of individual notes in a mixture of simultaneous notes. The approach to this problem is divided into two stages. The first stage consists of obtaining the magnitude of the fundamental frequency of an individual note to determine its intensity out of a mixture of simultaneous notes, on condition that the corresponding pitches of which are given. Two simultaneous notes one or two octaves apart are also included in this study. The second stage consists of generating, artificially, a mixture of notes from a recorded single-note database, subsequently referred to as “estimated mixture”. The time lag between individual notes in the estimated mixture is adjusted, so that the residual between which and the input comes to a minimum. The proposed method is verified with real data and the result is satisfactory.
Download Generating similarity-based playlists using travleling salesman algorithms
When using a mobile music player en-route, usually only little attention can be paid to its handling. Nonetheless it is desirable that all music stored in the device can be accessed quickly, and that tracks played in a sequence should match up. In this paper, we present an approach to satisfy these constraints: a playlist containing all tracks stored in the music player is generated such that in average, consecutive pieces are maximally similar. This is achieved by applying a Traveling Salesman algorithm to the pieces, using timbral similarities as the distances. The generated playlist is linear and circular, thus the whole collection can easily be browsed with only one input wheel. When a chosen track finishes playing, the player advances to the consecutive tracks in the playlist, generally playing tracks similar to the chosen track. This behavior could be a favorable alternative to the wellknown shuffle function that most current devices – such as the iPod shuffle, for example – have. We evaluate the fitness of four different Traveling Salesman algorithms for this purpose. Evaluated aspects were runtime, the length of the resulting route, and the genre distribution entropy. We implemented a Java applet to demonstrate the application and its usability.
Download Comparing synthetic and real templates for dynamic time warping to locate partial envelope features
In this paper we compare the performance of a number of different templates for the purposes of split point identification of various clarinet envelopes. These templates were generated with AttackDecay-Sustain-Release (ADSR) descriptions commonly used in musical synthesis, along with a set of real templates obtained using k-means clustering of manually prepared test data. The goodness of fit of the templates to the data was evaluated using the Dynamic Time Warping (DTW) cost function, and by evaluating the square of the distance of the identified split points to the manually identified split points in the test data. It was found that the best templates for split point identification were the synthetic templates followed by the real templates having a sharp attack and release characteristic, as is characteristic of the clarinet envelope.
Download Event Synchronous Wavelet Transform Approach to the Extraction of Musical Music Thumbnails
Fast browsing of digital collections of music would largely benefit from the availability of representative audio excerpts of the pieces. Similar to their visual counterparts found in digital photo albums, music thumbnails should offer a comprehensive listening experience while requiring a limited storage space or communication data rate. The approach to the generation of musical thumbnails of music proposed in this paper is based on an application of the PitchSynchronous Wavelet Transform, where the “pitch” is tuned to the elementary measure of the piece. The music thumbnail is encoded by the low rate coefficient sequence pertaining to the scaling residue of the transform. The scaling component represents the pseudo-periodic trend of the piece over several measures. Due to pseudo-periodicity, the time duration of the thumbnail can be arbitrarily extended in listening with no audible artifacts.
Download Improved adjustable boundary condition for the 2-D finite-difference time-domain mesh
The digital waveguide (DWG) mesh is a method for simulating wave propagation in multiple dimensions. Boundary conditions are needed for modeling changes in wave propagation media such as walls and furniture in a room or boundaries of a resonating membrane of a musical instrument. The boundary conditions have been solved for a one-dimensional DWG structure, but there is no known exact solution for the multi-dimensional mesh. In this work, a new boundary structure is introduced for modeling reflection coefficient values −1 ≤ r ≤ 1 in two dimensions. The new method gives remarkably more accurate results than the earlier approximations, especially at the low absolute values of r. At incident angles of Θ < 60o , the absolute error of reflection coefficient r is below 0.1 at frequencies 0.004 < f < 0.222 relative to the sampling frequency and at 60o ≤ Θ ≤ 80o the same result is reached at 0.005 < f < 0.114.
Download Sound Synthesis for Nonlinear Plates
In this paper, a simple finite difference scheme for a rectangular dynamic nonlinear plate, under free boundary conditions is presented. The algorithm is straightforward to program, and is capable of reproducing, to a first approximation, the behaviour of various percussion instruments whose timbre depends crucially on nonlinear effects (due to high-speed strikes), including transient pitch glides and the buildup of high-frequency energy. Though computationally intensive, algorithms such as that presented here promise more faithful sound synthesis and, as with all physical model inspired synthesis algorithms, require the specification of only a few, physically meaningful parameters. Full details of the algorithm, including the setting of boundary conditions and computational demands are provided. Numerical simulation results are presented.
Download Measuring Diffusion in a 2D Digital Waveguide Mesh
The digital waveguide mesh is a method by which the propagation of sound waves in an acoustic system can be simulated. An important consideration in modelling such systems is the accurate modelling of reflection characteristics at boundaries and surfaces. A significant property of an acoustic boundary is its diffusivity. In fact partially diffuse sound reflections are observed at most real acoustic surfaces and so this is an important consideration when implementing a digital waveguide mesh model. This paper presents a method for modelling diffusion that offers a high degree of control. The model is implemented with varying amounts of diffusivity, and a method for measuring its diffusive properties is outlined. Results for the model are presented and a method to calculate the diffusion coefficient is described.
Download Performing Expressive Rhythms with BillaBoop Voice-Driven Drum Generator
In a previous work we presented a system for transcribing spoken rhythms into a symbolic score. Thereafter, the system was extended to process the vocal stream in real-time in order to allow a musician to use it as a voice-driven drum generator. Extensions to this work are the following. First we achieved a study of the system classification accuracy based on typical onomatopoeia used in western beat boxing, with the perspective of building a general supervised model for immediate use. Also, we want the user to be able to generate expressive rhythms, beyond the symbolic drum representation. Thus we considered a class-specific mapping of continuous vocal stream descriptors with either effects or synthesis parameters of the drum generator. The extraction of the symbolic drum stream is implemented in the BillaBoop VST Core plug-in. The class-specific mapping and the sound synthesis are carried out in Plogue Bidule 1 framework. All these components are integrated into a low-latency application that allows its use for live performances.
Download Extraction of long-term structures in musical signals using the empirical mode decomposition
Long-term musical structures provide information concerning rhythm, melody and the composition. Although highly musically relevant, these structures are difficult to determine using standard signal processing. In this paper, a new technique based on the time-domain empirical mode decomposition is explained which enables us to analyse both short-term information and long-term structures in musical signals. It provides insight into perceived rhythms and their relationship to the signal. The technique is explained, and results are reported and discussed. Keywords: Empirical Mode Decomposition (EMD), Music Analysis, Santur, Long-term Structures, Fundamental Frequency, Rhythm.