Effects of healthy lingual local sense on formant frequencies of Persian vowels

In order to evaluate the effects of healthy lingual local sense on the phonetic quality of Persian vowels, changes in their main acoustic features were analyzed following local anesthesia the surface and sides of the tongue to partly block the normal neural feedback mechanisms in speech. Six Persian vowels (/a/, /o/, /u/, /e/, /i/, /æ/) were prolonged 3 times using habitual loudness with and without lingual local anesthesia (Lidocaine Hydrochloride Oral Topical Solution, USP (Viscous) 2%) by 5 male speakers. The formant frequencies of vowels (F1and F2) were analyzed and compared using the Speech Studio Package (Laryngograph Ltd). The difference between mean values of F1 and F2 before and after lingual local anesthesia were not statistically different for the /a/, /æ/ and /u/ vowels (p<0.05). The mean value of F1 after local anesthesia was not significantly different for the /o/ vowel (p<0.05); however, the mean value of F2 in the anesthetized condition was statistically different for the /o/ vowel (p>0.05). The mean value of F2 for this vowel was decreased to 262 Hz. The difference between the mean values of F1 and F2 before and after local anesthesia were also significantly different for the /e/ and /i/ vowels (p>0.05). According to our results, lingual local sense has effects on the production of some Persian vowels. Perhaps the healthy local sense of the tongue and normal articulatory models has an important role in the production of vowels.