Abstract
Purpose: Hearing-impaired (HI) speakers show changes in vowel production and formant frequencies, as well as more cases of overlapping between vowels and more restricted formant space, than hearing speakers. This study was intended to explore whether the use of different acoustic parameters (Formant Centralization Ratio (FCR), Vowel Space Area (VSA), F2i/F2u ratio (second formant of/i,u/)) was suitable or not for characterizing impairments in the articulation of vowels in the speech of HL speakers. In fact, correlated acoustic parameters are used to determine the limits of tongue movements in vowel production in different severity degrees of hearing impairment.
Methods: Speech recordings of 40 speakers with HL and 40 healthy controls were acoustically analyzed. The vowels (/a/,/i/,/u/) were extracted from the word context and, then, the first and second formants were calculated. The same vowel-formant elements were used to construct the FCR, expressed as (F2u + F2a + F1i + F1u)/(F2i + F1a), the F2i/F2u ratio, and the vowel space area (VSA), expressed as ABS((F1i*(F2a–F2u)+F1a*(F2u–F2i)+F1u*(F2i–F2a))/2).
Results: The FCR differentiated HL groups from the control group and the discrimination was not gender-sensitive. All parameters were found to be strongly correlated with each other.
Conclusions: The findings of this study showed that FCR was a more sensitive acoustic parameter than F2i/F2u ratio and VSA to distinguish speech of the HL groups from that of the normal group. Thus, FCR is considered to be applicable as an early objective measure of impaired vowel articulation in HL speakers.
Acknowledgements
The authors thank the children participated in the study and their parents and we thank Tehran University of Medical Science for tools and equipments.
Disclosure statement
No potential conflict of interest was reported by the authors.
Additional information
Notes on contributors
Ehsan Naderifar
Ehsan Naderifar is lecturer of Speech and language pathology department at Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran. His research interests include acoustic analysis, voice disorders and dysphagia. He has published some articles in national and international journals.
Ali Ghorbani
Ali Ghorbani is lecturer of Speech and language pathology department at Iran University of Medical Sciences, Tehran, Iran. He has worked in university for about 30 years. His research interests focus on hearing loss and articulation disorders.
Negin Moradi
Negin Moradi is associated professor of Speech and language pathology department at Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran. Her research interests focus on acoustic analysis, voice disorders and dysphagia.
Hossein Ansari
Hussain Ansari is graduated in MSc degree of epidemiology from Shiraz University of Medical Science in 2005. He is employed as academic member in Zahedan University of medical Sciences in 2006. He started the PhD degree of epidemiology in Tehran University of medical Sciences in 2010 and is graduated in 2014. At present he is associated professor of epidemiology in department of epidemiology and biostatistics in Zahedan University of Medical Sciences. He has published many articles in national and international journals and his H index is 14 based on the Scopus database.