Download Low Complexity Parametric Stereo Coding in MPEG-4
Parametric stereo coding in combination with a State-of-the-Art coder for the underlying monaural audio signal results in the most ef cient coding scheme for stereo signals at very low bit rates available today. This paper reviews those aspects of the parametric stereo paradigm that are important for audio coding applications. A complete parametric stereo coding system is presented, which was recently standardized in MPEG-4 Audio. Using complex modulated lter banks, it allows implementation with low computational complexity. The system is backward compatible and enables high quality stereo coding at total bit rate of 24 kbit/s when used in combination with aacPlus.
Download Computational Real-Time Sound Simulation of Rain
Real time sound synthesis in computer games using physical modeling is an area of great potential. To date, most sounds are prerecorded to match a certain event. Instead, by using a model to describe the sound producing event, a number of problems encountered when using pre-recorded sounds can be avoided. This paper deals with the application of physical modeling to the sound synthesis of rainfall. The implementation of a real-time simulation and a graphics interface allowing an interactive control of rainfall sound are discussed.
Download A Strategy for the Modular Implementation of Physics-Based Models
For reasons of practical handling as well as optimization of the processes of development and implementation, it is desirable to realize realtime models of sound emitting physical processes in a modular fashion that reflects an intuitively understandable structure of the underlying scenario. At the same time, in discrete– time algorithms based on physical descriptions, the occurance of non–computable instantaneous feedback loops has to be avoided. The latter obstacle prohibits the naive cross-connection of input– output signal processing blocks. The following paper presents an approach to gain modularity in the implementation of physicsbased models, while preventing non–computable loops, that can be applied to a wide class of systems. The strategy has been realized pratically in the development of realtime sound models in the course of the Sounding Object  European research project.
Download Implementing Loudness Models in MATLAB
In the field of psychoacoustic analysis the goal is to construct a transformation that will map a time waveform into a domain that best captures the response of a human perceiving sound. A key element of such transformations is the mapping between the sound intensity in decibels and its actual perceived loudness. A number of different loudness models exist to achieve this mapping. This paper examines implementation strategies for some of the more well-known models in the Matlab software environment.
Download Timbral Attributes for Objective Quality Assessment of the Irish Tin Whistle
In this paper we extract various timbral attributes for a variety of Irish tin whistles, and use these attributes to form an objective quality assessment of the instruments. This assessment is compared with the subjective experiences of a number of professional musicians. The timbral attributes are drawn from those developed in the Timbre Model .
Download Single-Note Ornamentation Transcription for the Irish Tin Whistle Based on Onset Detection
Ornamentation plays a very important role in Irish Traditional music, giving more expression to the music by altering or embellishing small pieces of a melody. Single-note ornamentation, such as cuts and strikes, are the most common type in Irish Traditional music and are played by articulating the note pitch during the onset stage. A technique for transcribing single note ornamentation for the tin whistle based on onset detection is presented. This method focuses on the characteristics of the tin whistle within Irish traditional music, customising a time-frequency based representation for detecting the instant when new notes played using single-note ornamentation start and release.
Download Efficiently Computable Similarity Measures for Query by Tapping Systems
A Query by Tapping system is a database which contains metadata descriptions of songs. The database can be scanned by tapping the melody line’s rhythm of a song requested on a MIDI keyboard or an e-drum. For the processing of queries the system computes the similarity of the query and the content inside the database by applying a similarity measure. Due to the high number of comparison processes in large databases efficiently computable similarity measures are needed. This paper presents two efficiently computable similarity measures which evaluate rhythmic properties of monophonic melodies represented in an MPEG-7 compliant manner. The usage and effectiveness is presented and evaluated with the real time capable Query by Tapping system BeatBank.
Download An Open Source Tool for Semi-Automatic Rhythmic Annotation
We present a plugin implementation for the multi-platform WaveSurfer sound editor. Added functionalities are the semi-automatic extraction of beats at diverse levels of the metrical hierarchy as well as uploading and downloading functionalities to a music metadata database. It is built upon existing open source (GPL-licenced) audio processing tools, namely WaveSurfer, BeatRoot and CLAM, in the intent to expand the scope of those softwares. It is therefore also provided as GPL code with the explicit goal that researchers in the audio processing community can freely use and improve it. We provide technical details of the implementation as well as practical use cases. We also motivate the use of rhythmic metadata in Music Information Retrieval scenarios.
Download A Spectral-Filtering Approach to Music Signal Separation
The task of separating a mix of several inter-weaving melodies from a mono recording into multiple tracks is attempted by filtering in the spectral domain. The transcribed score is provided in MIDI format a priori. In each time frame a filter is constructed for each instrument in the mix, whose effect is to filter out all harmonics of that instrument from the DFT spectrum. The complication of overlapping harmonics arising from separate notes is discussed and two filter shapes that were found to be fairly successful at separating overlapping harmonics are presented. In comparing the separated audio tracks to the original instrumental parts, signalto-residual ratios (SRR’s) in excess of 20 dB have been achieved. Audio demonstrations are on the internet .
Download Audio Processing Using Haskell
The software for most today’s applications including signal processing applications is written in imperative languages. Imperative programs are fast because they are designed close to the architecture of the widespread computers, but they don’t match the structure of signal processing very well. In contrast to that, functional programming and especially lazy evaluation perfectly models many common operations on signals. Haskell is a statically typed, lazy functional programming language which allow for a very elegant and concise programming style. We want to sketch how to process signals, how to improve safety by the use of physical units, and how to compose music using this language.