English: Let ${\displaystyle p}$ and ${\displaystyle q}$ be relative prime numbers that establish a musical interval between frequencies ${\displaystyle f_{q}}$ and ${\displaystyle f_{p}}$ that are less than one octave apart. It helps to also define a low frequency ${\displaystyle f_{0}}$ and a high frequency ${\displaystyle f_{\text{x}}}$. All these frequencies (and associated periods) are shown in the table to the left. Note that:

${\displaystyle f_{p}=pf_{0},\,}$ ${\displaystyle f_{q}=qf_{0},\,}$ ${\displaystyle qf_{p}=pf_{q},\,}$ and ${\displaystyle \,pT_{p}=T_{0},\,}$ ${\displaystyle qT_{q}=T_{0},\,}$ ${\displaystyle pT_{p}=qT_{q}\,.}$

Also: ${\displaystyle f_{0}<f_{q}<f_{p}<f_{\text{x}}\,}$ and ${\displaystyle T_{\text{x}}<T_{p}<T_{q}<T_{0}\,.}$