The sliding three-tube (S3T) model, based on Fant's acoustic theory and proposed in our previous studies, has a simple structure, enabling it to produce human-like vowels useful for education in acoustics and speech science. In this study, we changed the size of the S3T model and combined it with sound sources with different fundamental frequencies. We confirmed that the models could produce vowels of different speaker types. We were able to retain good vowel quality for a perceptual study when we simultaneously shortened vocal-tract length and increased fundamental frequency. We also discussed the models in a new way, comparing children's and adults' vowels, especially for educational purposes.

Index Terms: physical models of the human vocal tract, vowel production, education in acoustics, speech science