Clinical Study Acoustic Correlates of Compensatory Adjustments to the Glottic and Supraglottic Structures in Patients with Unilateral Vocal Fold Paralysis Luis M. T. Jesus, 1,2 Joana Martinez, 1 Andreia Hall, 1,3 and Aníbal Ferreira 4 1 Institute of Electronics and Informatics Engineering of Aveiro (IEETA), University of Aveiro, 3810-193 Aveiro, Portugal 2 School of Health Sciences (ESSUA), University of Aveiro, 3810-193 Aveiro, Portugal 3 Department of Mathematics (DMat), University of Aveiro, 3810-193 Aveiro, Portugal 4 Department of Electrical and Computer Engineering, University of Porto, 4200-465 Porto, Portugal Correspondence should be addressed to Luis M. T. Jesus; lmtj@ua.pt Received 22 January 2015; Accepted 24 April 2015 Academic Editor: Haldun Oguz Copyright © 2015 Luis M. T. Jesus 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. Te goal of this study was to analyse perceptually and acoustically the voices of patients with Unilateral Vocal Fold Paralysis (UVFP) and compare them to the voices of normal subjects. Tese voices were analysed perceptually with the GRBAS scale and acoustically using the following parameters: mean fundamental frequency (F0), standard-deviation of F0, jitter (ppq5), shimmer (apq11), mean harmonics-to-noise ratio (HNR), mean frst (F1) and second (F2) formants frequency, and standard-deviation of F1 and F2 frequencies. Statistically signifcant diferences were found in all of the perceptual parameters. Also the jitter, shimmer, HNR, standard-deviation of F0, and standard-deviation of the frequency of F2 were statistically diferent between groups, for both genders. In the male data diferences were also found in F1 and F2 frequencies values and in the standard-deviation of the frequency of F1. Tis study allowed the documentation of the alterations resulting from UVFP and addressed the exploration of parameters with limited information for this pathology. 1. Introduction A neural dysfunction of the larynx leads to alterations in voice, respiration, and airway protection. Usually, Unilat- eral Vocal Fold Paralysis (UVFP) is related to a set of well-documented perceptive alterations such as weak voice, breathiness, roughness, diminished voice intensity, vocal efort, low voice efciency, voice breaks, diplophonia, and air loss [1–5]. Furthermore, vocal strain is a critical component in various vocal pathologies including UVFP. A neuronal dys- phonia, such as UVFP, can alter the vibrational patterns of the Vocal Folds (VF) which leads to compensatory adjustments to the glottic and supraglottic structures that increase the vocal efort and vocal strain perception [6, 7]. In addition to the perceptive alterations, UVFP also results in higher values of jitter and shimmer and lower values of the harmonics-to- noise ratio (HNR) [1–4, 8]. Furthermore, values of standard- deviation of fundamental frequency (F0) are reported as higher than normal because of the diminished control of the vibrational pattern of the VF, causing greater variability [9– 11]. According to Schwarz et al. [6], there is a need to describe and understand the UVFP patient’s larynx confguration for a better and more individualised vocal intervention, preventing compensatory adjustments. Formant frequencies provide acoustic cues about the vocal tract confguration [12–14]. According to Lee et al. [15] the formant’s values are relevant for discriminating normal from pathologic voices and the confguration of the vocal tract is diferent during phonation in people with vocal pathologies. Te same authors [15] found slightly lower values of the frst formant (F1) frequency and higher values of the second formant (F2) frequency in cases of UVFP. Tis indicates that UVFP subjects tend to have a more elevated and advanced tongue position during phonation [13, 14]. A breathy voice (common in UVFP) is reported to be associated with the same confguration referred to previously [16]. However, Titze [13] reports an approximation of the Hindawi Publishing Corporation BioMed Research International Volume 2015, Article ID 704121, 9 pages http://dx.doi.org/10.1155/2015/704121