> ## Documentation Index
> Fetch the complete documentation index at: https://hanabiaiinc-docs-platform-create-voice.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# English Phoneme Control

> Control English pronunciation with CMU Arpabet

## Overview

English phoneme control uses CMU Arpabet, the pronunciation format used by CMUdict.

Wrap the pronunciation for one word in `<|phoneme_start|>` and `<|phoneme_end|>`, and keep surrounding punctuation outside the tag.

```text theme={null}
I am an <|phoneme_start|>EH1 N JH AH0 N IH1 R<|phoneme_end|>.
```

<Note>
  IPA is not supported for English phoneme tags. Convert IPA pronunciations to
  CMU Arpabet before using phoneme control.
</Note>

## CMU Arpabet

CMU Arpabet is written as space-separated uppercase symbols. Vowels can include stress digits:

* `0` for unstressed vowels.
* `1` for primary stress.
* `2` for secondary stress.

For the full symbol inventory, see the CMUdict [`cmudict.symbols`](https://github.com/cmusphinx/cmudict/blob/master/cmudict.symbols) list. You can also look up words on the [CMU Pronouncing Dictionary](http://www.speech.cs.cmu.edu/cgi-bin/cmudict) page.

Example:

```text theme={null}
Standard: I am an engineer.
With phoneme control: I am an <|phoneme_start|>EH1 N JH AH0 N IH1 R<|phoneme_end|>.
```

You can omit stress digits when you only need a rough pronunciation, but CMUdict-style output with stress digits usually gives the model the clearest signal.

## Common Examples

Use phoneme control when spelling alone is ambiguous:

```text theme={null}
The <|phoneme_start|>R IY1 D<|phoneme_end|> endpoint returns the current state.
The book was <|phoneme_start|>R EH1 D<|phoneme_end|> yesterday.
```

```text theme={null}
The <|phoneme_start|>B EY1 S<|phoneme_end|> line is too loud.
The <|phoneme_start|>B AE1 S<|phoneme_end|> swam upstream.
```

```text theme={null}
The <|phoneme_start|>P OW1 L IH0 SH<|phoneme_end|> team joined the call.
Please <|phoneme_start|>P AA1 L IH0 SH<|phoneme_end|> the final mix.
```

Use it for product names, acronyms, and technical terms:

```text theme={null}
Deploy with <|phoneme_start|>K UW2 B ER0 N EH1 T IY0 Z<|phoneme_end|>.
The query uses <|phoneme_start|>EH1 S K Y UW1 EH1 L<|phoneme_end|>.
```

## Generate CMU Arpabet

The training pipeline uses CMUdict-style pronunciations. You can generate the same format with the `cmudict` package:

```bash theme={null}
pip install cmudict
```

```python theme={null}
import cmudict


entries = cmudict.dict()


def cmu_pronunciation(word: str) -> str | None:
    phones = entries.get(word.lower())
    if not phones:
        return None
    return " ".join(phones[0])


print(cmu_pronunciation("engineer"))
# EH1 N JH AH0 N IH1 R
```

CMUdict may contain multiple pronunciations for the same word. Listen to the result and choose the variant that matches your intended accent or context.

## Practical Tips

* Replace only the word whose pronunciation needs control.
* Strip punctuation before dictionary lookup, then place punctuation after the tag.
* Use CMU Arpabet for English phoneme tags.
* For names and brands, write the pronunciation that you want the listener to hear, not necessarily the spelling.