No description available.

To understand how speech is produced by individual human beings, it is fundamentally important to be able to determine exactly the three-dimensional shape of the vocal tract. The vocal tract is inaccessible so its exact form is difficult to determine with live subjects. There is a wide variety of methods that provide information on the vocal tract shape. The technique of Electropalatography (EPG) is cheap, relatively simple, non-invasive and highly informative. Using EPG on its own, it is possible to deduce information about the shape, movement and position of tongue-palate contact during continuous speech. However, data provided by EPG is in the form of a two-dimensional representation in which all absolute positional information is lost. This thesis describe the development of an enhanced Electropalatography (eEPG) system, which retains most of the advantages of EPG while overcoming some of the disadvantages by representing the three-dimensional (3D) shape of the palate. The eEPG system uses digitised palate shape data to display the tongue-palate contact pattern in 3D. The 3D palate shape is displayed on a Silicon Graphics workstation as a surface made up of polygons represented by a quadrilateral mesh. EPG contact patterns are superimposed onto the 3D palate shape by displaying the relevant polygons in a different colour. By using this system, differences in shape between individual palates, apparent on visual inspection of the actual palates, are also apparent in the image on screen. The contact patterns can be related more easily to articulatory features such as the alveolar ridge since the ridge is visible on the 3D display. Further, methods have been devised for computing absolute distances along paths lying on the palate surface. Combining this with calibrated palate shape data allows measurements accurate to 1 mm to be made between contact locations on the palate shape. These have been validated with manual measurements. The sampling rate for EPG is 100Hz and the data rate is equivalent to 62 bits per 10ms. In the past few years, some coding (parameterization) methods have been introduced to try to reduce the amount of data while retaining the important aspects. Feature coding methods are proposed here and several parameters are investigated, expressed in terms of both conventional measures such as row number, and in absolute measures of distance and area (i.e. mm and mm2). Features studied include location of constriction and degree of constriction. Finally, in order to reduce the amount of data while retaining the spatial information, composite frames that represent a series of EPG frames are computed. Measures of goodness of the composite frames that do and do not use 3D data are described. Some example are given in which fricative data has been processed by generating a composite frame for the entire fricative, and computing an area estimate for each row of the composite frame using the assumption of a flat tongue. This thesis demonstrates the current capability and inherent flexibility of the enhanced electropalatography system. In the future, the eEPG system can be extended to compute volume estimates again using a flat tongue model. By incorporating information on the tongue surface provided by other imaging methods such as ultrasound, more accurate area and volume estimates can be obtained.

The field of biological acoustics has witnessed a steady increase in the research into overtone singing, or “throat-singing,” in which a singer utilizes resonance throughout the vocal tract to sing melodies with the overtones created by a vocal drone. Recent research has explored both how a singer vocalizes in order to obtain rich harmonics from a vocal drone, as well as how further manipulations of the vocal apparatus function to filter and amplify selected harmonics. In the field of phonetics, vowel production is quantified by measuring the frequencies of vocal tract resonances, or formants, which a speaker manipulates to voice a particular vowel. Thus, an investigation of throat singing is closely linked to human speech production. Formants are usually detected in vowel spectra obtained using Fast Fourier Transform algorithms (FFTs). An alternative method that provides much higher frequency resolution is external excitation of the vocal tract and measurement of the pressure response signal at the mouth’s opening, which can be used to calculate the acoustic impedance spectrum. We demonstrate the use of such an “acoustic impedance meter” to measure the formant frequencies of common vowels as well as the oscillatory modes of simple resonant pipe systems. The impedance meter accurately measures fundamental pipe modes and a variety of formant frequencies with an uncertainty of 1 Hz. Finally, we assess how the impedance meter may be used to measure the unique resonances achieved by qualified throat singers.

No description available.

This thesis is a study of the production of human speech sounds by acoustic modelling and signal analysis. It concentrates on sounds that are not produced by voicing (although that may be present), namely plosives, fricatives and aspiration, which all contain noise generated by flow turbulence. It combines the application of advanced speech analysis techniques with acoustic flow-duct modelling of the vocal tract, and draws on dynamic magnetic resonance image (dMRI) data of the pharyngeal and oral cavities, to relate the sounds to physical shapes. Having superimposed vocal-tract outlines on three sagittal dMRI slices of an adult male subject, a simple description of the vocal tract suitable for acoustic modelling was derived through a sequence of transformations. The vocal-tract acoustics program VOAC, which relaxes many of the assumptions of conventional plane-wave models, incorporates the effects of net flow into a one-dimensional model (viz., flow separation, increase of entropy, and changes to resonances), as well as wall vibration and cylindrical wavefronts. It was used for synthesis by computing transfer functions from sound sources specified within the tract to the far field. Being generated by a variety of aero-acoustic mechanisms, unvoiced sounds are somewhat varied in nature. Through analysis that was informed by acoustic modelling, resonance and anti-resonance frequencies of ensemble-averaged plosive spectra were examined for the same subject, and their trajectories observed during release. The anti-resonance frequencies were used to compute the place of occlusion. In vowels and voiced fricatives, voicing obscures the aspiration and frication components. So, a method was devised to separate the voiced and unvoiced parts of a speech signal, the pitch-scaled harmonic filter (PSHF), which was tested extensively on synthetic signals. Based on a harmonic model of voicing, it outputs harmonic and anharmonic signals appropriate for subsequent analysis as time series or as power spectra. By applying the PSHF to sustained voiced fricatives, we found that, not only does voicing modulate the production of frication noise, but that the timing of pulsation cannot be explained by acoustic propagation alone. In addition to classical investigation of voiceless speech sounds, VOAC and the PSHF demonstrated their practical value in helping further to characterise plosion, frication and aspiration noise. For the future, we discuss developing VOAC within an articulatory synthesiser, investigating the observed flow-acoustic mechanism in a dynamic physical model of voiced frication, and applying the PSHF more widely in the field of speech research.

The focus of this thesis is to investigate the role of voice pitch (the perception of fundamental frequency and/or corresponding harmonics) and apparent vocal tract length (VTL-the perception of the vocal tract resonances i.e. formant frequencies) in perceptions of trustworthiness and other related social attributions. Past research has found that women trust men with relatively higher pitched voices as long-term romantic partners. People with relatively higher pitched voices are also judged as more cooperative than people with relatively lower pitched voices. However, women choose men with relatively lower pitched voices when asked to select which leaders are more trustworthy and make better economic decisions. In study 1, I used “The Trust Game” to determine whether women trust men with higher or lower pitched voices to evenly divide a sum of money. Women trusted men with relatively higher pitched voices more often. Thus, even though men with lower pitched voices are more often elected to office, and are CEOs of larger companies that make more money, women trust men with relatively low pitched voices less than men with relatively high pitched voices to equitably distribute money. Surprisingly, no studies have examined the relationship between VTL and trust, but one recent study examined the relationship between VTL and perceptions of cooperation. In study 2, I was the first to test the role of voice pitch and VTL on perceptions of trust and cooperation. In general, people with higher frequency voices (high pitch and a shorter VTL) were relatively more cooperative and trustworthy than people with lower frequency voices (low pitch and a longer VTL). Despite correlations between the effects of voice frequency manipulations on ratings of trustworthiness and cooperativeness, the amount to which people thought pitch and VTL affected cooperativeness and trustworthiness was different enough to determine that these two constructs overlap, but are not synonymous. Together, these studies show that despite the fact that masculine men tend to win political elections and run large and successful companies, they are viewed as uncooperative and untrustworthy. Future research should investigate if those who win political elections and run successful companies do so because they keep more than their fair share of money. / Thesis / Master of Science (MSc)

No description available.

The purpose of this study was to further develop a multi-tier model of the vocal tract area function in which the modulations of shape to produce speech are generated by the product of a vowel substrate and a consonant superposition function. The new approach consists of specifying input parameters for a target consonant as a set of directional changes in the resonance frequencies of the vowel substrate. Using calculations of acoustic sensitivity functions, these "resonance deflection patterns" are transformed into time-varying deformations of the vocal tract shape without any direct specification of location or extent of the consonant constriction along the vocal tract. The configuration of the constrictions and expansions that are generated by this process were shown to be physiologically-realistic and produce speech sounds that are easily identifiable as the target consonants. This model is a useful enhancement for area function-based synthesis and can serve as a tool for understanding how the vocal tract is shaped by a talker during speech production. (C) 2016 Elsevier B.V. All rights reserved.

The field of biological acoustics has witnessed a steady increase in the research into overtone singing, or “throat-singing,” in which a singer utilizes resonance throughout the vocal tract to sing melodies with the overtones created by a vocal drone. Recent research has explored both how a singer vocalizes in order to obtain rich harmonics from a vocal drone, as well as how further manipulations of the vocal apparatus function to filter and amplify selected harmonics. In the field of phonetics, vowel production is quantified by measuring the frequencies of vocal tract resonances, or formants, which a speaker manipulates to voice a particular vowel. Thus, an investigation of throat singing is closely linked to human speech production. Formants are usually detected in vowel spectra obtained using Fast Fourier Transform algorithms (FFTs). An alternative method that provides much higher frequency resolution is external excitation of the vocal tract and measurement of the pressure response signal at the mouth’s opening, which can be used to calculate the acoustic impedance spectrum. We demonstrate the use of such an “acoustic impedance meter” to measure the formant frequencies of common vowels as well as the oscillatory modes of simple resonant pipe systems. The impedance meter accurately measures fundamental pipe modes and a variety of formant frequencies with an uncertainty of 1 Hz. Finally, we assess how the impedance meter may be used to measure the unique resonances achieved by qualified throat singers.

How important is the player???s vocal tract in clarinet and saxophone performance? Acoustician???s opinions have ranged from ???negligible??? [Backus (1985), JASA 78, 17] to ???vocal tract resonance frequencies must match the frequency of the required notes??? [Clinch et al. (1982), Acustica 50, 280]. Musicians??? opinions are similarly varied. To understand how the tract-reed-bore system interacts, acoustical measurements of performers??? vocal tracts during playing were made using measurement heads mounted in the mouthpieces of a clarinet and a tenor saxophone. Acoustic impedance spectra of the tenor and soprano saxophone bores were also measured for all standard fingerings, and some others. For fingerings high in the tenor saxophone???s second register, bore impedance peaks downstream decrease with increasing pitch. Above the first 2.7 octaves, peak values fall below 30 MPa.s.m-3 and this ends the standard range available to amateurs. To play the higher altissimo notes, experts produced strong vocal tract resonances upstream with impedances 10-40 MPa.s.m-3 tuned to sound the desired note. While expert saxophonists adjust their vocal tract thus for altissimo playing, inexperienced players do not, and consequently cannot produce these notes. The smoothly rising clarinet glissando solo opening Gershwin???s Rhapsody in Blue was also investigated. Partially uncovering an open finger-hole smoothly raises clarinet resonances in the lower register, allowing continuous increases in playing pitch. When pitch bending in the second (clarino) register, experienced players produced strong tract resonances with impedances up to 60 MPa.s.m-3, comparable in magnitude with those of the clarinet bore (40-50 MPa.s.m-3). Thus during the glissando, sounding pitch is controlled by smoothly varying a strong resonance in the player???s vocal tract. The phase of the reed impedance is shown to make downwards pitch bending easier than upwards. Similar vocal tract adjustments were observed on the clarinet and saxophone for other advanced techniques such as bugling and multiphonic selection. During normal playing, although experienced players produced vocal tract impedance peaks with only moderate magnitude, these peaks were adjusted systematically to frequencies about 150 Hz higher than the sounding pitch (determined by strong bore resonances). This strategy may avoid the effects of small unwanted tract-bore interactions on sounding pitch.