Identifying voice individuality is a key issue in the biometrics field. Previous studies have demonstrated that voice individuality is caused by differences in the shape and size of the vocal organs; however, these studies did not discuss voice individuality over a long term that includes periods of voice change. Therefore, we focus on adolescence (early teens to early twenties), which includes voice changes due to growth of vocal organs, and we reveal invariant voice individuality over a long period. In this study, the immature and mature periods during vocal organ development were defined as unstable and stable periods, respectively. We performed speaker verification tests across these two periods and evaluated voice features that are common to these periods using Fisher's F-ratio. The results of the speaker verification test demonstrated a verification accuracy of 60% or more in most cases, and the results of the evaluation using Fisher's F-ratio demonstrated that robust voice individuality existed in the frequency regions of 1-2 kHz and 4-6 kHz regardless of the period. These results suggest that voice individuality is unaffected by age-related changes over the long term, including adolescence.
Keywords: Fisher’s F-ratio; adolescence; deep learning; speaker verification; voice individuality.