Similarly, (Hacki and Heitmuller, 1999) also found a lowering of the shouting pitch for both sexes from 10-year-old. They tested 180 healthy children aged from 4 to 12 measured by VRP. They also found a lowering of the habitual speaking pitch as well as speaking pitch range for girls between 7 and 8, for boys between 8 and 9, which is partly similar to Wuyts et al (2003). The habitual speaking pitch in this study is from #a3 -#c4, similar to a3 - c4 in the Figure 3 in SFF section. The singing voice range was expanded both upward and downward with age.The author reported that singing pitch range was expaned from aged 4 to 8, but no considerable change for aged 8 -12. However, the singing range did expand slightly during aged 8-12, from g3-g5 to #f3- a6 for boys, and g3-a5 to g3-c6 for girls (see Table 2,p S143). Overall, girls have about 1-2 ST higher high singing pitch than that of boys since aged 8, while boys have about 1-2 ST lower bass than that of gilrs since aged 9, but these are nonlinear increase.The bass for girls aged 4-6 was unchanged, similarly with aged 8-10 girls, and aged 5-7 for boys. It might be as the bass are stable in these periods, and did not changed more than one semitone. The singing range was similar to finding from Bohme and Stuchlik, Schneider et al, and Wuyts, et al (2003).