Effects of transitory lingual nerve impairment on speech: an acoustic study of vowel sounds.
OBJECTIVE
The purpose of the study was to evaluate the effects of the lingual nerve impairment on phonetic quality of speech by analyzing the main acoustic features of vowel sounds when the normal lingual nerve function was partly distorted by local anesthesia.


METHODS
The study group consisted of 7 men, whose right side lingual nerve was anesthetized with 0.8 mL of Ultracaine D-Suprarenin (Aventis Pharma Deutschland GmpH, Frankfurt am Main, Germany). The speech material analyzed consisted of 8 vowels produced in sentence context by speakers. Every utterance was repeated 10 times with and without local anesthesia. After recording, the speech samples were analyzed with a computerized speech laboratory. In addition, the vowels of 1 man with permanent nerve impairment were studied.


RESULTS
The results show that the deprived function of the tongue after lingual nerve impairment had various effects on vowel quality for every subject. The main acoustic determinants of different vowels, the lowest vocal tract resonances, changed in frequency. In addition, the total duration of vowels changed and the vowels had different fundamental frequencies. However, these effects were extremely individual and variable.


CONCLUSIONS
According to the results of acoustic analysis, the distortion of lingual nerve function has effects on vowel production. Some of these changes were so extensive that they also could be perceptually detectable. Lingual nerve impairment seems to have potential to change speech production.
Niemi
Matti
M
Department of Oral and Maxillofacial Surgery, University of Turku, Turku, Finland.
Laaksonen
Juha-Pertti
JP
Vähätalo
Kimmo
K
Tuomainen
Jyrki
J
Aaltonen
Olli
O
Happonen
Risto-Pekka
RP
D000162:Acoustics; D000328:Adult; D000779:Anesthetics, Local / Q000009:adverse effects; D001184:Articulation Disorders / Q000209:etiology* / Q000503:physiopathology; D002355:Carticaine / Q000009:adverse effects; D006801:Humans; D008036:Lingual Nerve / Q000187:drug effects / Q000503:physiopathology*; D061222:Lingual Nerve Injuries; D008297:Male; D008875:Middle Aged; D010700:Phonetics; D013018:Sound Spectrography; D018709:Statistics, Nonparametric; D014059:Tongue / Q000503:physiopathology
D000779:Anesthetics, Local; C030488:Ultracaine D-S; D002355:Carticaine