# CreateSpeechRequest
## Properties
**model** | **String** | One of the available [TTS models](/docs/models#tts): `tts-1`, `tts-1-hd`, `gpt-4o-mini-tts`, or `gpt-4o-mini-tts-2025-12-15`. |
**input** | **String** | The text to generate audio for. The maximum length is 4096 characters. |
**instructions** | Option<**String**> | Control the voice of your generated audio with additional instructions. Does not work with `tts-1` or `tts-1-hd`. | [optional]
**voice** | [**models::VoiceIdsOrCustomVoice**](VoiceIdsOrCustomVoice.md) | |
**response_format** | Option<**String**> | The format to audio in. Supported formats are `mp3`, `opus`, `aac`, `flac`, `wav`, and `pcm`. | [optional]
**speed** | Option<**f64**> | The speed of the generated audio. Select a value from `0.25` to `4.0`. `1.0` is the default. | [optional]
**stream_format** | Option<**String**> | The format to stream the audio in. Supported formats are `sse` and `audio`. `sse` is not supported for `tts-1` or `tts-1-hd`. | [optional]
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