Modeling the voice source in terms of spectral slopesa)

The Journal of the Acoustical Society of America, 2010

Little is known about the perceptual importance of changes in the shape of the source spectrum, although many measures have been proposed and correlations with different vocal qualities ͑breathiness, roughness, nasality, strain…͒ have frequently been reported. This study investigated just-noticeable differences in the relative amplitudes of the first two harmonics ͑H1-H2͒ for speakers of Mandarin and English. Listeners heard pairs of vowels that differed only in the amplitude of the first harmonic and judged whether or not the voice tokens were identical in voice quality. Across voices and listeners, just-noticeable-differences averaged 3.18 dB. This value is small relative to the range of values across voices, indicating that H1-H2 is a perceptually valid acoustic measure of vocal quality. For both groups of listeners, differences in the amplitude of the first harmonic were easier to detect when the source spectral slope was steeply falling so that F0 dominated the spectrum. Mandarin speakers were significantly more sensitive ͑by about 1 dB͒ to differences in first harmonic amplitudes than were English speakers. Two explanations for these results are possible: Mandarin speakers may have learned to hear changes in harmonic amplitudes due to changes in voice quality that are correlated with the tones of Mandarin; or Mandarin speakers' experience with tonal contrasts may increase their sensitivity to small differences in the amplitude of F0 ͑which is also the first harmonic͒.

Journal of Speech, Language, and Hearing Research, 2019

Objective This investigation addresses the loudness variations in sones achievable with spectral slope variations (higher harmonic energy) in human vocalization and compares it to the sound pressure level (SPL) variations typically reported in the voice range profile (VRP). Method The primary methodology was computational. The ISO standard 226 was used to convert SPL values to sones for a 125- to 1000-Hz range of fundamental frequency and a –3 dB/octave to –12 dB/octave range of spectral slope. In addition, a retrospective analysis of human subjects' VRPs was conducted, and the experimental results were compared to the theoretical results. Results A very small range of SPL variation (less than 5 dB) in the VRP can produce a large range of loudness. The sensitivity can be on the order of 4 sones per dB SPL change. Conclusion For vocalization in the modal register, loudness variation is not well described by SPL change in dB, especially at high fundamental frequencies where the SP...

Journal of Voice, 2023

This in silico study explored the effects of a wide range of fundamental frequency (fo), source-spectrum tilt (SST), and vibrato extent (VE) on commonly used frequency and amplitude perturbation and noise measures. Method. Using 53 synthesized tones produced in Madde, the effects of stepwise increases in fo , intensity (modeled by decreasing SST), and VE on the PRAAT parameters jitter % (local), relative average perturbation (RAP) %, shimmer % (local), amplitude perturbation quotient 3 (APQ3) %, and harmonics-to-noise ratio (HNR) dB were investigated. A secondary experiment was conducted to determine whether any fo effects on jitter, RAP, shimmer, APQ3, and HNR were stable. A total of 10 sinewaves were synthesized in Sopran from 100 to 1000 Hz using formant frequencies for /a/, /i/, and /u/-like vowels, respectively. All effects were statistically assessed with Kendall's tau-b and partial correlation. Results. Increasing fo resulted in an overall increase in jitter, RAP, shimmer, and APQ3 values, respectively (P < 0.01). Oscillations of the data across the explored f o range were observed in all measurement outputs. In the Sopran tests, the oscillatory pattern seen in the Madde fo condition remained and showed differences between vowel conditions. Increasing intensity (decreasing SST) led to reduced pitch and amplitude perturbation and HNR (P < 0. 05). Increasing VE led to lower HNR and an almost linear increase of all other measures (P < 0.05). Conclusion. These novel data offer a controlled demonstration for the behavior of jitter (local) %, RAP %, shimmer (local) %, APQ3 %, and HNR (dB) when varying fo , SST, and VE in synthesized tones. Since humans will vary in all of these aspects in spoken language and vowel phonation, researchers should take potential resonance-harmonics type effects into account when comparing intersubject or preintervention and postintervention data using these measures.

Voice quality is an important perceptual cue in many disciplines, but knowledge of its nature is limited by a poor understanding of the relevant psychoacoustics. This article (aimed at researchers studying voice, speech, and vocal behavior) describes the UCLA voice synthesizer, software for voice analysis and synthesis designed to test hypotheses about the relationship between acoustic parameters and voice quality perception. The synthesizer provides experimenters with a useful tool for creating and modeling voice signals. In particular, it offers an integrated approach to voice analysis and synthesis and allows easy, precise, spectral-domain manipulations of the harmonic voice source. The synthesizer operates in near real time, using a parsimonious set of acoustic parameters for the voice source and vocal tract that a user can modify to accurately copy the quality of most normal and pathological voices. The software, user's manual, and audio files may be downloaded from http://brm.psychonomic-journals.org/content/supplemental. Future updates may be downloaded from www.surgery.medsch.ucla.edu/glottalaffairs/.

Many glottal source models have been proposed, but none has been systematically validated perceptually. Our previous work showed that model fitting of the negative peak of the flow derivative is the most important predictor of perceptual similarity to the target voice. In this study, a new voice source model is proposed to capture perceptually-important source shape aspects. This new model, along with four other source models, was fitted to 40 voice sources (20 male) obtained by inverse filtering and analysis-by-synthesis (AbS) of samples of natural normal and pathologic phonation. We generated synthetic copies of the voices using each modeled source pulse, with all other synthesis parameters held constant, and then conducted a visual sort-and-rate task in which listeners assessed the extent of perceived similarity between the target voice samples and each copy. Results showed that the proposed model provided a more accurate fit and a better perceptual match to the target than did the other models.

Journal of Speech, Language, and Hearing Research, 1993

The reliability of listeners’ ratings of voice quality is a central issue in voice research because of the clinical primacy of such ratings and because they are the standard against which other measures are evaluated. However, an extensive literature review indicates that both intrarater and interrater reliability fluctuate greatly from study to study. Further, our own data indicate that ratings of vocal roughness vary widely across individual clinicians, with a single voice often receiving nearly the full range of possible ratings. No model or theoretical framework currently exists to explain these variations, although such a model might guide development of efficient, valid, and standardized clinical protocols for voice evaluation. We propose a theoretical framework that attributes variability in ratings to several sources (including listeners’ backgrounds and biases, the task used to gather ratings, interactions between listeners and tasks, and random error). This framework may g...

Proceedings of the Fourth …, 2011

The reliability of listeners' ratings of voice quality is a central issue in voice research because of the clinical primacy of such ratings and because they are the standard against which other measures are evaluated. However, an extensive literature review indicates that both intrarater and interrater reliability fluctuate greatly from study to study. Further, our own data indicate that ratings of vocal roughness vary widely across individual clinicians, with a single voice often receiving nearly the full range of possible ratings. No model or theoretical framework currently exists to explain these variations, although such a model might guide development of efficient, valid, and standardized clinical protocols for voice evaluation. We propose a theoretical framework that attributes variability in ratings to several sources (including listeners' backgrounds and biases, the task used to gather ratings, interactions between listeners and tasks, and random error). This framework may guide development of new clinical voice and speech evaluation protocols, ultimately leading to more reliable perceptual ratings and a better understanding of the perceptual qualities of pathological voices.

Although voices provide listeners with significant information about speakers, defining and quantifying voice quality remain elusive goals. The ANSI standard definition of quality (that attribute of auditory sensation in terms of which a listener can judge that two sounds similarly presented and having the same loudness and pitch are dissimilar) is often criticized because it specifies what quality is not, rather than what it is. It has also proven difficult to devise measurement protocols for quality as specified in the ANSI definition. We argue that the ANSI definition is in fact appropriate, because it treats quality as the result of perceptual processesinteractions between listeners and signals in the context of specific perceptual goals. Application of speech synthesis in method-of-adjustment tasks allows measurement of quality psychoacoustically as those aspects of the signal that allow a listener to determine that two sounds of equal pitch and loudness are different, consistent with the ANSI definition, and provides insight into the salient acoustic attributes contributing to quality. This technique holds promise for improving the reliability and validity of measures of voice quality. WHAT IS VOICE? THE DEFINITIONAL DILEMMA The speaking voice naturally conveys information about the speaking individual, and voice quality serves as a primary means by which speakers project their physical, psychological, and social characteristics to the world (Laver, 1980). Although voice is central to a range of human activities, it has proven difficult to provide a single, useful, all-purpose definition of voice, and several senses of the term are in common use. Voice can be defined narrowly as sound produced by vibration of the vocal folds, or broadly as essentially synonymous with speech. Details of phonation and articulation, pitch and amplitude variations, and temporal patterning all contribute to how a speaker sounds, and broad definitions of voice reflect this fact. Which stage in the voice production process receives definitional focus depends on the interest of the practitioner, experimenter, or listener.

Proceedings of the AES 38th International Conference: Sound Quality Evaluation, Piteå, Sweden, June 13–15, 2010., 2010

Voice quality needs its own theory that must provide a conceptual framework for the main ideas of the field as well as some explanatory power, describe or at least propose possible mechanisms for the phenomena addressed, and suggest methods of attack on unsolved problems. Establishing a framework would lead to a more cohesive vocabulary. It would provide a platform to guide thought and discussion about voice quality related phenomena. One of the features of such a theory should be the mapping between the signal and the percepts, or between the “subjective” and the “objective.”