Electrolarynx Prototype With Adjustable Period Perturbation and Fundamental Frequency: Acoustic Analysis and Perceptual Preferences.

Abstract

Introduction: The electrolarynx restores speech after total laryngectomy, but its sound quality differs from that of the human voice.

Objectives: (a) To implement acoustic modifications in an electrolarynx-period perturbation and fundamental frequency adjustment; (b) to compare modified and conventional configurations through blinded perceptual evaluations by speech-language pathologists; and (c) to analyze laryngectomee preferences and their relationship with voice-related quality of life.

Study design: Prospective study.

Methods: A prototype electrolarynx was developed to allow adjustment of acoustic parameters. An adult woman with no anatomical or functional alterations in the vocal tract produced sustained /a/ vowels using both conventional and modified configurations. These samples were analyzed for temporal and spectral characteristics. In addition, ten laryngectomized individuals (nine men, one woman) used both versions to produce connected speech. Recordings were randomized and blindly evaluated by seven speech-language pathologists. Participants also evaluated their own recordings and completed the Voice-Related Quality of Life (V-RQOL) questionnaire.

Results: The conventional device lacked period perturbation and operated at a fixed fundamental frequency of 120 Hz. The modified configuration introduced a randomized perturbation pattern with uniform distribution (jitter: 0.5%) and adjusted fundamental frequency based on age and gender (110-175 Hz). Acoustic analysis revealed that conventional emissions had fixed waveforms, reflecting the mechanical activation pattern of the electrolarynx, and exhibited diffuse spectral energy. In contrast, modified emissions more closely resembled natural voice patterns, with clearer formant peaks. All speech-language pathologists (100%, n = 7) preferred the modified sound, citing greater intelligibility and reduced noise; 85.7% (n = 6) found it more suitable for the speaker's age and gender, and 71.4% (n = 5) rated it more natural. Among laryngectomized individuals, 50% (n = 5) preferred the modified sound, 10% (n = 1) the conventional, and 40% (n = 4) perceived no difference. Preference for the modified configuration was more common among individuals with lower V-RQOL scores.

Conclusion: Compared with the conventional device, the modified device resulted in voice quality that more closely resembled those of natural human voice patterns.