Chapter 7: Voice Classification and Life-Span Changes

Equation 7.1. From this formula, we can see that fundamental frequency is inversely proportional to the vocal fold length; shorter folds produce higher frequencies, and longer folds produce lower frequencies. Also, F₀ is proportional to the square root of the tissue stress.

Equation 7.2. If we take Eq. 7.1 above and assume that the tissue stress is the same for everyone, we can derive this equation, which simply restates that F₀ is inversely proportional to the effective vocal fold length (the part which actually vibrates). This length is 60% longer for men than for women.