Publications by Year: In Press

In Press
J. H. Van Stan, A. J. Ortiz, D. Sternad, D. D. Mehta, C. Huo, and R. E. Hillman, “Ambulatory voice biofeedback: Acquisition and retention of modified daily voice use in patients with phonotraumatic vocal hyperfunction,” American Journal of Speech-Language Pathology, In Press.
M. D. Groll, et al., “Automated relative fundamental frequency algorithms for use with neck-surface accelerometer signals,” Journal of Voice, In Press. Publisher's VersionAbstract
OBJECTIVE: Relative fundamental frequency (RFF) has been suggested as a potential acoustic measure of vocal effort. However, current clinical standards for RFF measures require time-consuming manual markings. Previous semi-automated algorithms have been developed to calculate RFF from microphone signals. The current study aimed to develop fully automated algorithms to calculate RFF from neck-surface accelerometer signals for ecological momentary assessment and ambulatory monitoring of voice. METHODS: Training a set of 2646 /vowel-fricative-vowel/ utterances from 317 unique speakers, with and without voice disorders, was used to develop automated algorithms to calculate RFF values from neck-surface accelerometer signals. The algorithms first rejected utterances with poor vowel-to-noise ratios, then identified fricative locations, then used signal features to determine voicing boundary cycles, and finally calculated corresponding RFF values. These automated RFF values were compared to the clinical gold-standard of manual RFF calculated from simultaneously collected microphone signals in a novel test set of 639 utterances from 77 unique speakers. RESULTS: Automated accelerometer-based RFF values resulted in an average mean bias error (MBE) across all cycles of 0.027 ST, with an MBE of 0.152 ST and -0.252 ST in the offset and onset cycles closest to the fricative, respectively. CONCLUSION: All MBE values were smaller than the expected changes in RFF values following successful voice therapy, suggesting that the current algorithms could be used for ecological momentary assessment and ambulatory monitoring via neck-surface accelerometer signals.
E. S. Burckardt, R. E. Hillman, O. Murton, D. Mehta, J. Van Stan, and J. A. Burns, “The impact of tonsillectomy on the adult singing voice: Acoustic and aerodynamic measures,” Journal of Voice, In Press. Publisher's VersionAbstract
OBJECTIVE: Singers undergoing tonsillectomy are understandably concerned about possible sequelae to their voice. The surgical risks of laryngeal damage from intubation and upper airway scarring are valid reasons for singers to carefully consider their options for treatment of tonsil-related symptoms. No prior studies have statistically assessed objective voice outcomes in a group of adult singers undergoing tonsillectomy. This study determined the impact of tonsillectomy on the adult singing voice by determining if there were statistically significant changes in preoperative versus postoperative acoustic, aerodynamic, and Voice-Related Quality of Life (VRQOL) measures. STUDY DESIGN: Prospective cohort study. SETTING: Tertiary Referral Academic Hospital SUBJECTS: Thirty singers undergoing tonsillectomy from 2012 to 2019. METHODS: Acoustic recordings were obtained with Computerized Speech Lab (CSL) (Pentax CSL 4500) and analyzed with the Multidimensional Voice Program (MDVP) (Pentax MDVP) and Pratt Acoustic Analysis Software. Estimates of aerodynamic vocal efficiency were obtained and analyzed using the Phonatory Aerodynamic System (Pentax PAS 6600). Preoperative VRQOL scores were recorded, and singers were instructed to refrain from singing for 3 weeks following tonsillectomy. Repeat acoustic and aerodynamic measures as well as VRQOL scores were obtained at the first postoperative visit. RESULTS: Average postoperative acoustic (jitter, shimmer, HNR) and aerodynamic (sound pressure level divided by subglottal pressure) parameters related to laryngeal phonatory function did not differ significantly from preoperative measures. The only statistically significant change in postoperative measures of resonance was a decrease in the 3rd formant (F3) for the /a/ vowel. Average postoperative VRQOL scores (79.8, SD18.7) improved significantly from preoperative VRQOL scores (89, SD12.2) (P = 0.007). CONCLUSIONS: Tonsillectomy does not appear to alter laryngeal voice production in adult singers as measured by standard acoustic and aerodynamic parameters. The observed decrease in F3 for the /a/ vowel is hypothetically related to increasing the pharyngeal cross-sectional area by removing tonsillar tissue, but this would not be expected to appreciably impact the perceptual characteristics of the vowel. Singers' self-assessment (VRQOL) improved after tonsillectomy.
K. L. Marks, et al., “Psychometric analysis of an ecological vocal effort scale in individuals with and without vocal hyperfunction during activities of daily living,” American Journal of Speech-Language Pathology, In Press. Publisher's VersionAbstract


The purpose of this study was to examine the psychometric properties of an ecological vocal effort scale linked to a voicing task.


Thirty-eight patients with nodules, 18 patients with muscle tension dysphonia, and 45 vocally healthy control individuals participated in a week of ambulatory voice monitoring. A global vocal status question was asked hourly throughout the day. Participants produced a vowel–consonant–vowel syllable string and rated the vocal effort needed to produce the task on a visual analog scale. Test–retest reliability was calculated for a subset using the intraclass correlation coefficient, ICC(A, 1). Construct validity was assessed by (a) comparing the weeklong vocal effort ratings between the patient and control groups and (b) comparing weeklong vocal effort ratings before and after voice rehabilitation in a subset of 25 patients. Cohen's d, the standard error of measurement (SEM), and the minimal detectable change (MDC) assessed sensitivity. The minimal clinically important difference (MCID) assessed responsiveness.


Test–retest reliability was excellent, ICC(A, 1) = .96. Weeklong mean effort was statistically higher in the patients than in controls (d = 1.62) and lower after voice rehabilitation (d = 1.75), supporting construct validity and sensitivity. SEM was 4.14, MDC was 11.47, and MCID was 9.74. Since the MCID was within the error of the measure, we must rely upon the MDC to detect real changes in ecological vocal effort.


The ecological vocal effort scale offers a reliable, valid, and sensitive method of monitoring vocal effort changes during the daily life of individuals with and without vocal hyperfunction.

L. E. Toles, et al., “Relationships among personality, daily speaking voice use, and phonotrauma in adult female singers,” Journal of Speech, Language, and Hearing Research, In Press.
L. E. Toles, A. J. Ortiz, K. L. Marks, D. D. Mehta, J. H. Van Stan, and R. E. Hillman, “Amount and characteristics of speaking and singing voice use in vocally healthy female college student singers during a typical week,” Journal of Voice, In Press. Publisher's VersionAbstract

Objectives: Singers, college students, and females are groups known to be at an elevated risk of developing functional/hyperfunctional voice disorders; therefore, female college students majoring in vocal performance may be at an even higher risk. To mitigate this risk, it would be helpful to know the "safe limits" for voice use that would help maintain vocal health in this vulnerable group, but there is a paucity of high-quality objective information upon which to base such limits. This study employed weeklong ambulatory voice monitoring in a large group of vocally healthy female college student singers to begin providing the types of objective data that could be used to help develop improved vocal health guidelines.

Methods: Participants included 64 vocally healthy females currently enrolled in a vocal performance or similar program at a college or university. An ambulatory voice monitor recorded neck-surface acceleration throughout a typical week. A singing classifier was applied to the data to separate singing from speech. Weeklong vocal dose measures and distributional characteristics for standard voice measures were computed separately for singing and speech, and for both types of phonation combined.

Results: Participants spent 6.2% of the total monitoring time speaking and 2.1% singing (with total phonation time being 8.4%). Singing had a higher fo mode, more pitch variability, higher average sound pressure level (SPL), negatively skewed SPL distributions, lower average CPP, and higher H1-H2 values than speaking.

Conclusions: These results provide a basis for beginning to establish vocal health guidelines for female students enrolled in college-level vocal performance programs and for future studies of the types of voice disorders that are common in this group. Results also demonstrate the potential value that ambulatory voice monitoring may have in helping to objectively identify vocal behaviors that could contribute to voice problems in this population.