A (音名)

音	音頻(Hz)	數學式	音	音頻(Hz)	數學式	音	音頻(Hz)	數學式
C	261.626	${\displaystyle {\begin{smallmatrix}{\frac {440}{{\sqrt[{4}]{2}}^{3}}}\end{smallmatrix}}}$	E	329.628	${\displaystyle {\begin{smallmatrix}{\frac {440}{{\sqrt[{12}]{2}}^{5}}}\end{smallmatrix}}}$	G♯	415.305	${\displaystyle {\begin{smallmatrix}{\frac {440}{\sqrt[{12}]{2}}}\end{smallmatrix}}}$
C♯	277.183	${\displaystyle {\begin{smallmatrix}{\frac {440}{{\sqrt[{3}]{2}}^{2}}}\end{smallmatrix}}}$	F	349.228	${\displaystyle {\begin{smallmatrix}{\frac {440}{\sqrt[{3}]{2}}}\end{smallmatrix}}}$	A	440	440
D	293.665	${\displaystyle {\begin{smallmatrix}{\frac {440}{{\sqrt[{12}]{2}}^{7}}}\end{smallmatrix}}}$	F♯	369.994	${\displaystyle {\begin{smallmatrix}{\frac {440}{\sqrt[{4}]{2}}}\end{smallmatrix}}}$	A♯	466.164	${\displaystyle {\begin{smallmatrix}440{\sqrt[{12}]{2}}\end{smallmatrix}}}$
D♯	311.127	${\displaystyle {\begin{smallmatrix}{\frac {440}{\sqrt[{2}]{2}}}\end{smallmatrix}}}$	G	391.995	${\displaystyle {\begin{smallmatrix}{\frac {440}{\sqrt[{6}]{2}}}\end{smallmatrix}}}$	B	493.883	${\displaystyle {\begin{smallmatrix}440{\sqrt[{6}]{2}}\end{smallmatrix}}}$

在十二平均律裡，A作為標準，設定為440hz。而A♯的頻率的計算方法是把A的頻率乘以${\displaystyle {\sqrt[{12}]{2}}}$ ，得出${\displaystyle {\begin{smallmatrix}440{\sqrt[{12}]{2}}\end{smallmatrix}}}$ hz（約等於466.164hz）。

A在十二律中对应南吕。

• A大調：A B C♯ D E F♯ G♯ A
• A小調
  • A自然小調：A B C D E F G A
  • A和聲小調：A B C D E F G♯ A
  • A旋律小調：A B C D E F♯ G♯ A G F E D C B A