Fundamental frequency variation with an electrolarynx improves speech understanding: A case study

Purpose: This study examined the effect of fundamental frequency (F0) variation on the intelligibility of speech in an alaryngeal talker who used an electrolarynx (EL). Method: One experienced alaryngeal talker produced variable F0 and a constant F0 with his EL as he read sentences aloud. As a control, a group of sentences with variable F0 was flattened at a constant F0. Twenty listeners heard these sentences in background noise and wrote down what they heard. Results: Speech understanding was on average 14% better with variable F0 controlled by the talker than the sentences produced with a constant F0 and the control sentences resynthesized with flattened F0. Conclusions: Variable F0 contributes to speech understanding in noise. Because speech produced by an EL is considered to have poorer intelligibility in relation to other alaryngeal methods, training alaryngeal talkers to use variable F0 may prove to be of significant benefit for communication for those who use electrolarynges.