# 1.2 音素（Phonemes）

在自然语音中，不可继续分割的组成部分被称为**音素**（phonemes）。英语的音素分为**元音**和**辅音**。

In natural speech, indivisible sound segments are referred to as *phonemes*. English language categorizes these phonemes into two types: *vowels* and *consonants*.

## 1.2.1 元音（Vowels）

英语总计约有 20 个**元音**。

English approximately has 20 *vowels*.

元音可以被分为短元音（*short vowels*）和**长元音**（*long vowels*）；与此同时，它们也可以分为**单元音**（*monophthongs*）和**双元音**（*diphthongs*）。

Vowels can be classified into *long* and *short* vowels, or alternatively, they can also be grouped as *monophthongs* and *diphthongs*.

| Monophthongs |                                   | Diphthongs                                     |
| ------------ | --------------------------------- | ---------------------------------------------- |
| Short vowels | `ʌ`, `e`, `ə`, `ɪ`, `ʊ`, `ɒ`      |                                                |
| Long vowels  | `ɑː`, `æ`, `əː`, `iː`, `uː`, `ɔː` | `aɪ`, `eɪ`, `ɔɪ`, `aʊ`, `oʊ`, `eə`, `ɪə`, `ʊə` |

6 个基础元音中，`ə` 和 `ɪ` 有相对更多的变体（*allophone*）：
In the 6 basic vowels, `ə` and `ɪ` have relatively more variants, or *allophones*:

* `ɪ`：
  * 除了长元音版本 `iː` 之外，还有一个半长版本 `i`，例如 *happy* `/ˈhæp·i/`[^1]；
  * In addition to the long vowel version `i`ː, there's also a semi-long version `i`, as in *happy* `/ˈhæp·i/`.
* `ə`：
  * 长元音版本 `əː` 在 CEPD[^2] 中被标注为 `ɜː`，例如 *bird* `/bɜːd/` (UK)
  * The long vowel version `əː` is annotated as `ɜː` in the CEPD[^2], like in *bird* `/bɜːd/` (UK).
  * 儿化的短元音 `ə` 被标注为 `ɚ`，例如 *mother* `/ˈmʌð·ɚ/`；
  * The rhotacized short vowel `ə` is annotated as `ɚ`, as in *mother* pronounced `/ˈmʌð·ɚ/`.
  * 儿化的长元音 `əː` 被标注为 `ɝː` 例如 *bird* `/bɝːd/` (US)
  * The rhotacized long vowel `əː` is annotated as `ɝː`, like in *bird* pronounced `/bɝːd/` (US).

另外，英式英语中还有两个三元音: `aɪə` 比如，*fire* `/faɪə/`；*hour* `/aʊə/`。在英式英语中，这两个三元音被简化为两个双元音的更为明显的儿化音，`aɪə` → `aɪr`，比如，*fire* `/faɪr/`, *hour* `/aʊr/`。

Furthermore, in British English, there are two triphthongs: `aɪə` as in *fire* pronounced `/faɪə/` and `aʊə` as in *hour* pronounced `/aʊə/`. In American English, these two triphthongs simplify into more apparent rhotacized diphthongs, `aɪə` → `aɪr`, for example, *fire* pronounced `/faɪr/`, and *hour* pronounced `/aʊr/`.

## 1.2.2 辅音（Consonants）

英文大约 28 个辅音。

English approximately has 28 *consonants*.

| Airflow   | Voiced or not | Consonants              |
| --------- | ------------- | ----------------------- |
| Plosive   | Voiceless     | `p`, `t`, `k`           |
|           | Voiced        | `b`, `d`, `g`           |
| Fricative | Voiceless     | `f`, `s`, `θ`, `ʃ`, `h` |
|           | Voiced        | `v`, `z`, `ð`, `ʒ`, `r` |
| Affricate | Voiceless     | `tʃ`, `tr`, `ts`        |
|           | Voiced        | `dʒ`, `dr`, `dz`        |
| Nasal     | Voiced        | `m`, `n`, `ŋ`           |
| Lateral   | Voiced        | `l`                     |
| Semivowel |               | `j`, `w`                |

辅音 `t` 在美式英语中有个弹舌音变体，`t̬`，例如，*cutting* `/ˈkʌt̬·ɪŋ/`。

The consonant `t` has a flapping variant, `t̬`, as in the word *cutting*, pronounced `/ˈkʌt̬·ɪŋ/`.

[^1]: The middle dot `·` in `/ˈhæp·i/` is an annotation of syllable division. A dot `.` is used in CEPD, but for clearer html rendering, we use a raised one here.
[^2]: CEPD, Cambridge English Pronunciation Dictionary, https://dictionary.cambridge.org/help/phonetics.html.