Modulating phonation through alteration of vocal fold medial surface contour

Abstract

Objectives 1. To test whether alteration of the vocal fold medial surface contour can improve phonation. 2. To demonstrate that implant material properties affect vibration even when implant is deep to the vocal fold lamina propria. Study Design Induced phonation of excised human larynges. Methods Thirteen larynges were harvested within 24 hours post-mortem. Phonation threshold pressure (PTP) and flow (PTF) were measured before and after vocal fold injections using either calcium hydroxylapatite (CaHA) or hyaluronic acid (HA). Small-volume injections (median 0.0625 mL) were targeted to the infero-medial aspect of the thyroarytenoid (TA) muscle. Implant locations were assessed histologically. Results The effect of implantation on PTP was material-dependent. CaHA tended to increase PTP, whereas HA tended to decrease PTP (Wilcoxon test P = 0.00013 for onset). In contrast, the effect of implantation on PTF was similar, with both materials tending to decrease PTF (P = 0.16 for onset). Histology confirmed implant presence in the inferior half of the vocal fold vertical thickness. Conclusions Taken together, these data suggested the implants may have altered the vocal fold medial surface contour, potentially resulting in a less convergent or more rectangular glottal geometry as a means to improve phonation. An implant with a closer viscoelastic match to vocal fold cover is desirable for this purpose, as material properties can affect vibration even when the implant is not placed within the lamina propria. This result is consistent with theoretical predictions and implies greater need for surgical precision in implant placement and care in material selection.

Quantitative Evaluation of the In Vivo Vocal Fold Medial Surface Shape

“…This is a question that many have tried to answer, and, as a result, the way in which we do injection laryngoplasty and the shape of our thyroplasty implants have evolved. 1,17,18 Titze found that a divergent prephonatory glottal configuration achieved lower oscillation threshold pressures correlating with greater ease of phonation. 3 However, other studies using physical models and numerical studies showed that the lowest phonation threshold pressure occurs for a rectangular or slightly convergent glottis.…”

“…18 Mau et al predicted that increasing vertical thickness (ie, glottal channel height) of the vocal folds and a more rectangular glottal geometry would lower phonation threshold pressure and flow. 1 Further, Courey tested injection material into different locations within the glottis and found that placement of graft in the medial aspect of the TA muscle reduced the forces necessary to bring the vocal folds into position for vibration. 17 The histology from that report also appeared to approximate a rectangular glottis.…”

“…Previous studies showed that an optimal medial surface geometry may exist, achieving the lowest phonation threshold pressure. 1–3 …”

Speaker-Independent Silent Speech Recognition From Flesh-Point Articulatory Movements Using an LSTM Neural Network

“…Laryngectomy is a surgical removal of the larynx for the treatment of laryngeal or other oral cavity cancers [1]; therefore, persons after laryngectomy lose their ability to produce speech sounds and suffer in their daily communication [2], [3]. Although there are several options to assist the speech communication for those patients such as esophageal speech, trachea-esophageal speech, and electrolaryngeal speech, these approaches generally produce an abnormal sounding voice with a pitch that is aberrantly low and limited in range [4].…”

Recognizing Whispered Speech Produced by an Individual with Surgically Reconstructed Larynx Using Articulatory Movement Data

“…People who have their larynx (vocal fold) impaired due to physical impairment or treatment of laryngeal cancer suffer during their daily life. A surgery can help these patients reconstruct or repair their larynx, but their phonation can hardly be completely recovered [1]. Patients with surgically reconstructed larynx generally have problems in controlling laryngeal functions, thus producing whispered speech with extreme hoarseness [2].…”