> ## Documentation Index > Fetch the complete documentation index at: https://developers.nlpearl.ai/llms.txt > Use this file to discover all available pages before exploring further. # Text to Speech (Streaming) > Generates speech from text with one of your voices and streams the audio as it is produced. ## OpenAPI ````yaml post /v2/Speech/Stream openapi: 3.0.1 info: title: NLPearl Client API description: A sample API that demonstrates features in the OpenAPI specification version: v2 servers: - url: https://api.nlpearl.ai description: Production Environement security: - bearer_auth: [] - oauth2_client_credentials: [] tags: - name: Pearl description: >- Manage your Pearls, the AI agents that handle your inbound and outbound calls. Create and configure Pearls, retrieve their details and settings, run or pause them, list and bulk-export their calls, monitor calls in progress, get analytics, and reset a customer's conversation memory. - name: Speech description: >- Turn text into speech with your voices, as a single clip or as a stream, and clone new voices from a recording. paths: /v2/Speech/Stream: post: tags: - Speech summary: Text to Speech (Streaming) description: >- Generates speech from text with one of your voices and streams the audio as it is produced. requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/SpeechRequestApi' example: text: Your appointment is confirmed for Thursday at ten. voiceId: 1cf704d389adfc067d749a51 modelId: nlpearl-v2-preview pace: medium tier: standard outputFormat: mp3_44100_128 responses: '200': description: The audio, streamed as it is generated. headers: X-Generation-Id: description: The id of this generation. schema: type: string X-Output-Format: description: The audio format, for example `mp3_44100_128`. schema: type: string X-Model: description: The model used. schema: type: string X-Tier: description: The tier you asked for. schema: type: string X-Tier-Charged: description: >- The tier you were charged for: `priority` only when the request went ahead of waiting requests, otherwise `standard`. schema: type: string content: audio/mpeg: schema: type: string format: binary audio/wav: schema: type: string format: binary audio/ogg: schema: type: string format: binary audio/L16: schema: type: string format: binary audio/basic: schema: type: string format: binary audio/x-alaw-basic: schema: type: string format: binary '400': description: '`invalid_request`. The message names the field.' content: application/json: schema: $ref: '#/components/schemas/SpeechErrorApi' '401': description: Missing or invalid credentials. '402': description: '`insufficient_credits` or `debt_limit_reached`.' content: application/json: schema: $ref: '#/components/schemas/SpeechErrorApi' '403': description: '`insufficient_scope` or `account_suspended`.' content: application/json: schema: $ref: '#/components/schemas/SpeechErrorApi' '404': description: '`voice_not_found`.' content: application/json: schema: $ref: '#/components/schemas/SpeechErrorApi' '429': description: '`concurrency_limit_exceeded`.' headers: Retry-After: description: Seconds to wait before retrying. schema: type: integer X-Concurrency-Limit: description: Speech requests your account may have in flight. schema: type: integer X-Concurrency-In-Use: description: Speech requests in flight when this one was refused. schema: type: integer content: application/json: schema: $ref: '#/components/schemas/SpeechErrorApi' '503': description: '`system_busy` or `account_unverified`.' headers: Retry-After: description: Seconds to wait before retrying. schema: type: integer content: application/json: schema: $ref: '#/components/schemas/SpeechErrorApi' components: schemas: SpeechRequestApi: required: - text - voiceId type: object properties: text: maxLength: 5000 minLength: 1 type: string description: The text to speak, in the voice's language. voiceId: type: string description: >- The voice to use. List your voices with [Get Voices](/api-reference/v2/pearlSettings/get-voices). modelId: type: string enum: - nlpearl-v2-preview default: nlpearl-v2-preview description: The speech model. pace: type: string enum: - very_slow - slow - medium - fast - very_fast default: medium description: How fast the voice speaks. tier: type: string enum: - standard - priority default: standard description: >- Your place in the queue when the service is busy. `priority` goes ahead of waiting `standard` requests and is charged at the Priority rate only when it did. outputFormat: type: string enum: - pcm_8000 - pcm_16000 - pcm_22050 - pcm_24000 - pcm_44100 - pcm_48000 - wav_8000 - wav_16000 - wav_22050 - wav_24000 - wav_44100 - wav_48000 - ulaw_8000 - alaw_8000 - mp3_22050_32 - mp3_44100_32 - mp3_44100_64 - mp3_44100_96 - mp3_44100_128 - mp3_44100_192 - opus_48000_32 - opus_48000_64 - opus_48000_96 - opus_48000_128 - opus_48000_192 default: mp3_44100_128 description: >- Codec, sample rate and bitrate of the audio, for example `mp3_44100_128`, `pcm_16000` or `ulaw_8000`. additionalProperties: false SpeechErrorApi: type: object properties: code: type: string description: The error code, for example `voice_not_found`. message: type: string description: What went wrong. securitySchemes: bearer_auth: type: http description: >- Specify the authorization token. For more information, check out the [Authorization Guide](/api-reference/authorization). scheme: bearer oauth2_client_credentials: type: oauth2 description: >- OAuth2 client_credentials grant. Use the Id of an OAuth API key as `client_id` and its one-time secret as `client_secret`. flows: clientCredentials: tokenUrl: /oauth/token scopes: pearls:read: List and view Pearls pearls:write: >- Create and update Pearls (settings, conversation flows, voices); implies pearls:read pearls:moderate: Run/pause Pearls and reset customer memory; implies pearls:read pearls:analytics: Read Pearl analytics; implies pearls:read pearls:leads: Manage and read outbound leads; implies pearls:read pearls:calls: >- Read calls and recordings, make and delete calls; implies pearls:read account:phone_numbers: >- Read account phone numbers and text channels, manage custom VoIP numbers, import Twilio numbers and delete phone numbers account:users: Read account users account:advanced: Manage advanced account settings (blacklist) account:billing: Read account information and credit balance account:audit_log: Read the audit log tts: Synthesise speech and clone voices ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.