🎵 音符频率计算器Note Frequency Calculator
根据十二平均律计算任意音符的频率：f = 参考频率 × 2^((n − 69)/12)，n 为 MIDI 音高。选择音名和八度（科学音高记号，A4 = 440 Hz），得到频率、MIDI 编号和声波波长；参考音 A4 可调（如 432 Hz）。Find any note's frequency in equal temperament: f = reference × 2^((n − 69)/12), where n is the MIDI pitch. Pick a note name and octave (scientific pitch notation, A4 = 440 Hz) to get the frequency, MIDI number and sound wavelength; the A4 reference is adjustable (e.g. 432 Hz).
使用说明与常见问题How-to & FAQ
「音符频率计算器」是什么？What is the Note Frequency Calculator tool?
根据十二平均律计算任意音符的频率：f = 参考频率 × 2^((n − 69)/12)，n 为 MIDI 音高。选择音名和八度（科学音高记号，A4 = 440 Hz），得到频率、MIDI 编号和声波波长；参考音 A4 可调（如 432 Hz）。Find any note's frequency in equal temperament: f = reference × 2^((n − 69)/12), where n is the MIDI pitch. Pick a note name and octave (scientific pitch notation, A4 = 440 Hz) to get the frequency, MIDI number and sound wavelength; the A4 reference is adjustable (e.g. 432 Hz).
如何使用「音符频率计算器」？How do I use the Note Frequency Calculator tool?
在「音符频率计算器」中，填写「音名」、「八度（科学音高记号）」、「A4 参考频率（Hz）」、「声速（m/s，用于波长）」等参数，结果会随输入实时计算并显示在下方。In the Note Frequency Calculator: Fill in "Note", "Octave (scientific pitch notation)", "A4 reference (Hz)", "Speed of sound (m/s, for wavelength)"; results are recalculated instantly as you type.
频率是怎么算出来的？How is the frequency calculated?
用十二平均律：f = 参考频率 × 2^((n − 69)/12)，其中 n 是 MIDI 音高编号，A4（MIDI 69）默认 440 Hz。每升高一个半音频率乘以 2^(1/12) ≈ 1.0595，升高一个八度频率翻倍。Equal temperament: f = reference × 2^((n − 69)/12), where n is the MIDI pitch number and A4 (MIDI 69) is 440 Hz by default. Each semitone multiplies the frequency by 2^(1/12) ≈ 1.0595, and each octave doubles it.
八度数字代表什么？What does the octave number mean?
采用科学音高记号：中央 C 是 C4，其上方的 A 是 A4 = 440 Hz。MIDI 的最低音 C 是 C-1（编号 0），钢琴最低音 A0 约 27.5 Hz。It uses scientific pitch notation: middle C is C4 and the A above it is A4 = 440 Hz. The lowest MIDI C is C-1 (number 0), and the lowest piano note A0 is about 27.5 Hz.
为什么可以改成 432 Hz？Why can the reference be set to 432 Hz?
标准音高是 A4 = 440 Hz，但有些乐手偏好 432 Hz 或乐团使用 442/443 Hz。改变参考频率会按比例平移所有音符的频率，方便对照不同调音标准。The standard pitch is A4 = 440 Hz, but some musicians prefer 432 Hz and some orchestras tune to 442 or 443 Hz. Changing the reference shifts every note's frequency proportionally, which helps compare tuning standards.
波长是怎么得到的？How is the wavelength found?
波长 λ = 声速 ÷ 频率。空气中 20 °C 时声速约 343 m/s，可按温度或介质修改。这是声波在空气中的波长，不是乐器弦长。Wavelength λ = speed of sound ÷ frequency. In air at 20 °C the speed is about 343 m/s, which you can change for a different temperature or medium. This is the sound wave's wavelength in air, not an instrument's string length.
「音符频率计算器」免费吗？需要注册吗？Is the Note Frequency Calculator free? Do I need an account?
「音符频率计算器」完全免费，无需注册或安装，打开网页即可使用，手机和电脑都能用；输入的内容只在你的浏览器本地处理。The Note Frequency Calculator is completely free with no sign-up or install and works on phones and desktops; what you enter is processed only in your browser.