Vocal fold vibratory and acoustic features in fatigued Karaoke singers

Session 3aMU - Musical Acoustics and Speech Communication: Singing Voice in Asian CulturesKaraoke is a popular singing entertainment particularly in Asia and is gaining more popularity in the rest of world. In Karaoke, an amateur singer sings with the background music and video (usually guided by the lyric captions on the video screen) played by Karaoke machine, using a microphone and an amplification system. As the Karaoke singers usually have no formal training, they may be more vulnerable to vocal fatigue as they may overuse and/or misuse their voices in the intensive and extensive singing activities. It is unclear whether vocal fatigue is accompanied by any vibration pattern or physiological changes of vocal folds. In this study, 20 participants aged from 18 to 23 years with normal voice were recruited to participate in an prolonged singing task, which induced vocal fatigue. High speed laryngscopic imaging and acoustic signals were recorded before and after the singing task. Images of /i/ phonation were quantitatively analyzed using the High Speed Video Processing (HSVP) program (Yiu, et al. 2010). It was found that the glottis became relatively narrower following fatigue, while the acoustic signals were not sensitive to measure change following fatigue. © 2012 Acoustical Society of Americapublished_or_final_versio

Novel MRI Technologies for Structural and Functional Imaging of Tissues with Ultra-short T₂ Values

Conventional MRI has several limitations such as long scan durations, motion artifacts, very loud acoustic noise, signal loss due to short relaxation times, and RF induced heating of electrically conducting objects. The goals of this work are to evaluate and improve the state-of-the-art methods for MRI of tissue with short T₂, to prove the feasibility of in vivo Concurrent Excitation and Acquisition, and to introduce simultaneous electroglottography measurement during functional lung MRI

Loudness of the singing voice: A room acoustics perspective

This thesis is examining ectophonic (sounds created outside the human body) and autophonic (sound from one’s own voice) loudness perception for the operatic voice, within the context of room acoustics. Ectophonic loudness perception was modelled within the context of room acoustics for the operatic voice in chapter two. These models were then used to explore the loudness envelope of the messa di voce (MDV), where psychoacoustically based measures were shown to perform better than physical acoustic measures used in previous studies. The third chapter addressed autophonic loudness perception, while presenting limitations in modelling it in a manner similar to ectophonic loudness models. Some of these limitations were addressed in chapter four with two experiments where autophonic loudness of opera singers was explored using direct psychoacoustical scaling methods, within simulated room acoustic environments. In the first experiment, a power law relationship between autophonic loudness and the sound pressures produced was noticed for the magnitude production task, with different power law exponents for different phonemes. The contribution of room acoustics for autophonic loudness scaling was not statistically significant. Lombard slope, as it applies to autophonic perception and room acoustics was also studied, with some evidence found in support. The second experiment in chapter four explored autophonic loudness for more continuous vocalisations (crescendi, decrescendi, and MDV) using adapted direct scaling methods. The results showed that sensorimotor mechanisms seem to be more important than hearing and room acoustics in autophonic loudness perception, which is consistent with previous research. Overall, this thesis showed that the room acoustics effect on the loudness of the singing voice needs to be assessed based on the communication scenario. This has relevance for voice analysis, loudness perception in general, room acoustics simulation, and vocal pedagogy

Predicting and auralizing acoustics in classrooms

Although classrooms have fairly simple geometries, this type of room is known to cause problems when trying to predict their acoustics using room acoustics computer modeling. Some typical features from a room acoustics point of view are: Parallel walls, low ceilings (the rooms are flat), uneven distribution of absorption, and most of the floor being covered with furniture which at long distances act as scattering elements, and at short distance provide strong specular components. The importance of diffraction and scattering is illustrated in numbers and by means of auralization, using ODEON 8 Beta

Waveguide physical modeling of vocal tract acoustics: flexible formant bandwidth control from increased model dimensionality

Digital waveguide physical modeling is often used as an efficient representation of acoustical resonators such as the human vocal tract. Building on the basic one-dimensional (1-D) Kelly-Lochbaum tract model, various speech synthesis techniques demonstrate improvements to the wave scattering mechanisms in order to better approximate wave propagation in the complex vocal system. Some of these techniques are discussed in this paper, with particular reference to an alternative approach in the form of a two-dimensional waveguide mesh model. Emphasis is placed on its ability to produce vowel spectra similar to that which would be present in natural speech, and how it improves upon the 1-D model. Tract area function is accommodated as model width, rather than translated into acoustic impedance, and as such offers extra control as an additional bounding limit to the model. Results show that the two-dimensional (2-D) model introduces approximately linear control over formant bandwidths leading to attainable realistic values across a range of vowels. Similarly, the 2-D model allows for application of theoretical reflection values within the tract, which when applied to the 1-D model result in small formant bandwidths, and, hence, unnatural sounding synthesized vowels