Research Article Modulation Spectra Morphological Parameters: A New Method to Assess Voice Pathologies according to the GRBAS Scale Laureano Moro-Velázquez, Jorge Andrés Gómez-García, Juan Ignacio Godino-Llorente, and Gustavo Andrade-Miranda ETSIST, Universidad Polit´ ecnica de Madrid, Campus Sur, Carretera de Valencia km 7, 28031 Madrid, Spain Correspondence should be addressed to Laureano Moro-Vel´ azquez; laureano.moro@upm.es Received 23 January 2015; Revised 4 May 2015; Accepted 4 May 2015 Academic Editor: Adam Klein Copyright © 2015 Laureano Moro-Vel´ azquez et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Disordered voices are frequently assessed by speech pathologists using perceptual evaluations. Tis might lead to problems caused by the subjective nature of the process and due to the infuence of external factors which compromise the quality of the assessment. In order to increase the reliability of the evaluations, the design of automatic evaluation systems is desirable. With that in mind, this paper presents an automatic system which assesses the Grade and Roughness level of the speech according to the GRBAS perceptual scale. Two parameterization methods are used: one based on the classic Mel-Frequency Cepstral Coefcients, which has already been used successfully in previous works, and other derived from modulation spectra. For the latter, a new group of parameters has been proposed, named Modulation Spectra Morphological Parameters: MSC, DRB, LMR, MSH, MSW, CIL, PALA, and RALA. In methodology, PCA and LDA are employed to reduce the dimensionality of feature space, and GMM classifers to evaluate the ability of the proposed features on distinguishing the diferent levels. Efciencies of 81.6% and 84.7% are obtained for Grade and Roughness, respectively, using modulation spectra parameters, while MFCCs performed 80.5% and 77.7%. Te obtained results suggest the usefulness of the proposed Modulation Spectra Morphological Parameters for automatic evaluation of Grade and Roughness in the speech. 1. Introduction With the aim of diagnosing and evaluating the presence of a voice disorder clinicians and specialists have developed diferent assessment procedures [1] such as exploration using laryngoscopic techniques, acoustic analysis, or perceptual evaluations. Te latter is widely used by clinicians to quantify the extent of a dysphony. Some well-known perceptual evaluation procedures are the Bufalo Rating Voice Profle [2], Consensus Auditory Perceptual Evaluation of Voice (CAPE- V) [3], and GRBAS [4]. Te main problem with perceptual analysis is the high intra/interrater variability [5, 6] due to the subjectivity of the assessment in which the experience of the evaluator, his/her physical fatigue, mental condition, and some other factors are involved. Hence, means such as acoustic analysis based on signal processing might be valuable in clinical scenarios, providing objective tools and indices which can directly represent the level of afection or at least help clinicians to make a more reliable and less subjective perceptual assessment. Tis noninvasive technique can complement and even replace other invasive methods of evaluation. Besides, the large amount of improvements in the feld of speech signal processing is addressed mostly to areas such as speech or speaker recognition. Many of these advances are being transferred to biomedical applications for clinical purposes; some recent examples are related to diferent uses such as telemonitoring of patients [7], telerehabilitation [8], or clinical-support systems [9]. However, there is a substan- tial quantity of research to be done for further enhancements. Roughly speaking, most of the studies in this feld can be divided into three main categories: the frst one is focused on developing automatic detectors of pathological voices Hindawi Publishing Corporation BioMed Research International Volume 2015, Article ID 259239, 13 pages http://dx.doi.org/10.1155/2015/259239