Hands-Free Wearable Electrolarynx using Linear Predictive Coding Residual Waves and Listening Evaluation

Masaki Takeuchi, Jaesol Ahn, Kunhak Lee, Ken Takaki, Tohru Ifukube, Ken-ichiro Yabu, Shinnosuke Takamichi, Rumi Ueha, Masaki Sekino
Vol. 11 (2022) p.68-75

A conventional electrolarynx (EL), which is used by laryngectomees, produces monotonous sound and occupies a user’s hand; hence, we developed a hands-free wearable device that improves voice quality. The proposed device estimates individual vocal tract features using linear predictive coding (LPC) and generates sound vibrations using an LPC inverse filter. Additionally, we reproduced the vibration sound using a transducer and amplified the first harmonic frequency and the second one. We conducted an objective experiment to compare the spectra of natural voice, a conventional EL, and the proposed device. We also conducted a subjective experiment in which we asked healthy subjects to listen to and evaluate the conventional EL and the proposed device. The results of the objective experiment demonstrated that our model was characterized by two formant peaks that were similar to the conventional EL and the natural voice. The results of the subjective experiment demonstrated that our model was more powerful and clearer than the conventional EL. These findings indicate that the voice of our device is spectrally close to human voice and gives the audience a more powerful and clearer sound.