Download Piano Transcription Using Pattern Recognition: Aspects on Parameter Extraction A method for chord recognition for piano transcription has been previously presented by the authors. The method presents some limitations due to errors in parameter extraction carried out during the training process. Parameter extraction of piano notes is not as straightforward as sometimes can be thought. Spectral components detection is necessary but not enough to obtain accurately some note parameters. The inharmonicity coefficient B is one of the parameters that are difficult to evaluate. The obtained value of B is different for every partial used to calculate it, and sometimes, these differences are high. Tuning with respect to tempered scale is another important note parameter. The problems arise when we try to measure the tuning of a note belonging to octaves 0 or 1, because the fundamental is radiated by the soundboard with a very low level and, therefore, it is not captured by the recording microphone and cannot be measured. A method to avoid these drawbacks is presented in this paper, including an explanation of the basis.
Download Source Separation for WFS Acoustic Opening Applications This paper proposes a new scheme to reduce coding bit rate in array based multichannel audio applications like the acoustic opening, which can be used for modern teleconference systems. The combination of beamforming techniques for source separation and wave field synthesis allows a significant coding bit rate reduction. To evaluate the quality of this new scheme, both objective and subjective tests have been carried out. The objective measurement system is based on the Perceptual Audio Quality Measure of the binaural signal that the listener would perceive in a real environment.
Download Source separation for microphone arrays using multichannel conjugate gradient techniques This paper proposes a new scheme to improve the source separation problem aimed to microphone array applications like WFS based teleconference systems. A multichannel, sub-band approach to reduce computational complexity is presented. Also, instead of using the LMS adaptive algorithm, a new system based on hybrid Conjugate Gradient-nLMS techniques is developed to accelerate the convergence time. This adaptive algorithm is controlled by a voice activity detector block that basically detects double talk situations and freezes the adaptation process to avoid the appearance of sound artifacts which may cause a significant degradation of the recovered signals and have a great impact in the quality of the full system.
Download Conjugate gradient techniques for multichannel acoustic echo cancellation Conjugate Gradient (CG) techniques are suitable for resolution of time-variant system identification problems: adaptive equalization, echo cancellation, active noise cancellation, linear prediction, etc. These systems can be seen as optimization problems and CG techniques can be used to solve them. It has been demonstrated that, in the single-channel case, the conjugate gradient techniques provide a similar solution in terms of convergence rate than those provided by the recursive least square (RLS) method, involving higher complexity than the least mean square (LMS) but lower than RLS without stability issues. The advantages of these techniques are especially valuable in the case of high complexity and magnitude problems like multi-channel systems. This work develops CG algorithm for the adaptive MIMO (multiple-input and multiple-output) systems and tests it by solving a multichannel acoustic echo cancellation (MAEC) problem.