Supplementary Material for: Intrinsic vowel fundamental frequency in children with and without hearing impairment

Introduction
It is well-established that high vowels tend to have a higher F0 than low vowels, a phenomenon known as Intrinsic Vowel F0 (IF0). However, the underlying cause of IF0 remains debated. Previous research suggests that IF0 is entirely of physiological origin, while other research indicates that it is acquired to enhance perceptual contrasts between vowels.
Methods
This study explored the impact of hearing loss on IF0 in six-year-old children, both with and without hearing impairment. The Belgian Dutch vowels produced by the children in both groups during a (non-)word repetition task were acoustically analysed for F0.
Results
The main result was that all children presented IF0. Although IF0 was not significantly different between children with and without hearing impairment, there was a trend towards a smaller IF0 in the hearing-impaired group.
Conclusion
In conclusion, while the results of this study support the physiological hypothesis, they also suggest a potential role for perceptual factors in shaping IF0. The results were interpreted in relation to the combined potential effects of speech organ physiology and perception on IF0.