审阅范围 · Review scope
指定内容与证据核对。请保留正文中的出处与限制；不代表全库最终验收、实际演奏或学习效果验证。
Specified content and evidence checks. Keep the evidence and limitations stated in the text in view. This is not final corpus acceptance or validation of performance or learning outcomes.
音程：字母跨度与半音距离要一起看
两个音按到了哪些琴键，和乐谱把它们写成什么关系，是两个要一起检查的问题。例如 C 到 E 与 C 到 Fb，在十二平均律钢琴上可以按到相同的两个键，却分别写成三度和四度。
先会找 C、D、E、F，并会数相邻琴键的步数，再读下面的表。还不熟悉音名、升降号或 C4 时，先看零基础入口。这里的“度数”数音名字母，“半音距离”数键盘上的最小步数；它们都不是音量大小。
【作者观点】《好和弦》第二章先用音名字母确定度数，再讨论大小、完全、增减；明确提醒同一键盘距离可以有不同写法。PDF-NC-BOOK，PDF 实际第 18–20 页，对应页脚印刷第 16–18 页。本轮读过 OCR，核对了第18、20页原图；谱例不能只靠机器识别。
两个坐标
【通用乐理】音程的度数按包含两端的字母音名计算，性质再由具体音高关系决定。升降记号会改变半音距离，却不把某个字母变成另一个字母。
【本库推导】比较以下上行音程：
| 写法 | 字母范围 | 半音距离 | 名称 |
|---|---|---|---|
| C4–E4 | C–D–E，三度 | 4 | 大三度 |
| C4–Fb4 | C–D–E–F，四度 | 4 | 减四度 |
| C4–F4 | C–D–E–F，四度 | 5 | 完全四度 |
在十二平均律钢琴上，前两组可按到相同琴键；它们的书写关系仍不同。这个表为本库自编推导，不取自来源谱例。
表中“大”“完全”“减”是音程名称的一部分，不是在评价声音好坏。三度中，相距4个半音叫大三度；四度中，相距5个半音叫完全四度，比它少1个半音叫减四度。这里先认识这三个例子，不要求一次背完全部音程表。
对读谱与移调有什么影响
【本库综合】辨认键盘位置与解释乐谱拼写是相互联系的任务。快速演奏可以利用熟悉的形状，但分析和移调时仍须保留原音名及声部走向。否则一次听起来等高的替换，可能丢掉作品为什么这样写的信息。
【本库综合】练习时分别记录“音高弹错”“字母度数判断错”“性质判断错”，才能决定该练键盘定位、音名跨度还是半音关系。参见实验 E10。
在图上分开看两种计数
先看双语音程图解：从C4出发，比较E4、Fb4与F4。字母跨度与键盘半音格数分列；图上向上的每一步代表一个半音，不是实体键盘的几何形状，也不发声。
【补充来源】本轮完整读过好和弦音程文章的文字，未检查其嵌入影片和全部图片。本文采用独立例子与计算，不复制它的图、记忆口令或练习编排；对复音程、重增减等情况，不能把入门表简化成涵盖全部音程的规则。
原创频率比伴读将频率比、半音数、音分和两种百分量分开；这些计算采用理想化模型，不能代替实际钢琴听辨或调律测量。
Intervals: letter span and semitone distance belong together
The keys you press and the relationship written in the score are two things to check together. C to E and C to Fb can use the same keys on an equal-tempered piano, yet are written as a third and a fourth.
First learn to find C/D/E/F and count steps between adjacent keys. If note names, accidentals or C4 are unfamiliar, begin at the beginner entry. Here, interval number counts letter names; semitone distance counts the smallest keyboard steps. Neither measures loudness.
[Author's view] Chapter two of PDF-NC-BOOK establishes letter-based interval number before major/minor, perfect and augmented/diminished qualities. It warns that the same keyboard distance can have different spellings. Physical pp. 18–20 correspond to printed pp. 16–18. OCR was read and images of pp. 18/20 checked; score examples cannot rely on OCR alone.
Two coordinates
[General theory] Interval number counts letter names inclusively. Quality then depends on the pitches. Accidentals change semitone distance without changing the letter name itself.
[Our derivation] Compare these ascending intervals:
| Spelling | Letter span | Semitones | Name |
|---|---|---|---|
| C4–E4 | C–D–E: third | 4 | Major third |
| C4–Fb4 | C–D–E–F: fourth | 4 | Diminished fourth |
| C4–F4 | C–D–E–F: fourth | 5 | Perfect fourth |
On a twelve-tone equal-tempered piano, the first two use the same keys but retain different written relationships. This table is our original derivation, not a copied source example.
“Major,” “perfect” and “diminished” are naming terms, not judgments of beauty. A four-semitone third is major. A five-semitone fourth is perfect; reducing it by 1 semitone makes it diminished. Learn these three examples before trying to memorize a full interval table.
Implications for reading and transposition
[Our synthesis] Keyboard location and spelling interpretation are connected tasks. Familiar shapes can help execution, but analysis and transposition must preserve note names and voice direction. An equal-pitch substitution can otherwise hide why the music is written that way.
[Our synthesis] Log wrong pitch, wrong letter-based number and wrong quality separately. These call for different work on keyboard location, letter span and semitone relationships. See E10.
Related: transposition and modes, reading, chord identity.
See two counts separately
Use the bilingual interval diagram: from C4 compare E4, Fb4 and F4. Letter span and keyboard semitone positions are separate. Each step upward represents a semitone, not the geometry of a physical keyboard; there is no sound.
[Supplementary source] The text of NiceChord's interval article was fully read in this pass, without reviewing embedded video or every image. Examples and arithmetic here are independent; its diagrams, memory phrases and teaching sequence are not reproduced. Introductory tables must not be treated as rules covering every compound or multiply altered interval.
The original frequency-ratio companion separates ratios, semitones, cents and two percentage measures. These idealized calculations do not replace piano listening or tuning measurements.