> ## Documentation Index > Fetch the complete documentation index at: https://docs.slng.ai/llms.txt > Use this file to discover all available pages before exploring further. # Cognigy TTS > Stream synthesized speech from SLNG over the Cognigy Voice Gateway WebSocket protocol using any supported text-to-speech model and voice. ## AsyncAPI ````yaml api-reference/asyncapi/bridges-cognigy.asyncapi.yaml /v1/bridges/cognigy/tts/{model_variant} id: /v1/bridges/cognigy/tts/{model_variant} title: Cognigy TTS Bridge description: >- Stream synthesized speech from SLNG over the Cognigy Voice Gateway WebSocket protocol using any supported text-to-speech model and voice. servers: - id: production protocol: wss host: api.slng.ai bindings: [] variables: [] - id: staging protocol: wss host: stageapi.slng.ai bindings: [] variables: [] address: /v1/bridges/cognigy/tts/{model_variant} parameters: [] bindings: - protocol: ws version: latest value: method: GET headers: type: object properties: X-Region-Override: type: string description: Target region override. Auto-selected if not provided. x-parser-schema-id: X-World-Part-Override: type: string description: Target world part override. Auto-selected if not provided. x-parser-schema-id: x-parser-schema-id: WebsocketHeaders query: type: object properties: region: type: string description: >- Target region override as a query parameter. Auto-selected if not provided. Equivalent to the `X-Region-Override` header; the header takes precedence when both are set. enum: - ap-southeast-2 - eu-north-1 - us-east-1 x-parser-schema-id: world-part: type: string description: >- Target world part override as a query parameter. Auto-selected if not provided. Equivalent to the `X-World-Part-Override` header; the header takes precedence when both are set. enum: - ap - eu - na x-parser-schema-id: x-parser-schema-id: WebsocketQueryParams schemaProperties: - name: method type: string description: GET required: false - name: headers type: object required: false properties: - name: X-Region-Override type: string description: Target region override. Auto-selected if not provided. required: false - name: X-World-Part-Override type: string description: Target world part override. Auto-selected if not provided. required: false - name: query type: object required: false properties: - name: region type: string description: >- Target region override as a query parameter. Auto-selected if not provided. Equivalent to the `X-Region-Override` header; the header takes precedence when both are set. enumValues: - ap-southeast-2 - eu-north-1 - us-east-1 required: false - name: world-part type: string description: >- Target world part override as a query parameter. Auto-selected if not provided. Equivalent to the `X-World-Part-Override` header; the header takes precedence when both are set. enumValues: - ap - eu - na required: false operations: - &ref_1 id: cognigyTtsBridgeReceiveStream title: Cognigy tts bridge receive stream description: Stream data to Cognigy TTS Bridge type: receive messages: - &ref_7 id: CognigyStreamMessage contentType: application/json payload: - name: Stream Message description: Send text to synthesize into audio for Cognigy TTS. type: object properties: - name: type type: string description: stream required: true - name: text type: string description: Text to synthesize required: true - name: pronunciation type: object description: >- Optional pronunciation hint applied to this text chunk. Forwarded to providers that support pronunciation dictionaries (e.g. IPA or SSML overrides). required: false properties: - name: mode type: string description: Pronunciation override mode (e.g. `ipa`, `ssml`). required: false - name: name type: string description: >- Identifier of the term whose pronunciation is being overridden. required: false - name: dictionary_id type: string description: Pronunciation dictionary identifier. required: false headers: [] jsonPayloadSchema: type: object description: Send text to synthesize into audio. required: - type - text properties: type: type: string const: stream x-parser-schema-id: text: type: string description: Text to synthesize x-parser-schema-id: pronunciation: type: object description: >- Optional pronunciation hint applied to this text chunk. Forwarded to providers that support pronunciation dictionaries (e.g. IPA or SSML overrides). properties: mode: type: string description: Pronunciation override mode (e.g. `ipa`, `ssml`). x-parser-schema-id: name: type: string description: >- Identifier of the term whose pronunciation is being overridden. x-parser-schema-id: dictionary_id: type: string description: Pronunciation dictionary identifier. x-parser-schema-id: x-parser-schema-id: x-parser-schema-id: title: Stream Message description: Send text to synthesize into audio for Cognigy TTS. example: |- { "type": "stream", "text": "Hello from Cognigy TTS bridge." } bindings: [] extensions: - id: x-parser-unique-object-id value: CognigyStreamMessage bindings: [] extensions: &ref_0 - id: x-parser-unique-object-id value: /v1/bridges/cognigy/tts/{model_variant} - &ref_2 id: cognigyTtsBridgeReceiveFlush title: Cognigy tts bridge receive flush description: Flush buffered output on Cognigy TTS Bridge type: receive messages: - &ref_8 id: CognigyFlushMessage contentType: application/json payload: - name: Flush Message (Cognigy) description: Flush any buffered audio to the Cognigy client. type: object properties: - name: type type: string description: flush required: true headers: [] jsonPayloadSchema: type: object description: Flush any buffered audio to the client. required: - type properties: type: type: string const: flush x-parser-schema-id: x-parser-schema-id: title: Flush Message (Cognigy) description: Flush any buffered audio to the Cognigy client. example: |- { "type": "flush" } bindings: [] extensions: - id: x-parser-unique-object-id value: CognigyFlushMessage bindings: [] extensions: *ref_0 - &ref_3 id: cognigyTtsBridgeReceiveStop title: Cognigy tts bridge receive stop description: Stop session on Cognigy TTS Bridge type: receive messages: - &ref_9 id: CognigyTtsStopMessage contentType: application/json payload: - name: Stop Message (Cognigy TTS) description: Stop synthesis and close the Cognigy TTS session. type: object properties: - name: type type: string description: stop required: true headers: [] jsonPayloadSchema: type: object description: Stop synthesis and close the session. required: - type properties: type: type: string const: stop x-parser-schema-id: x-parser-schema-id: title: Stop Message (Cognigy TTS) description: Stop synthesis and close the Cognigy TTS session. example: |- { "type": "stop" } bindings: [] extensions: - id: x-parser-unique-object-id value: CognigyTtsStopMessage bindings: [] extensions: *ref_0 - &ref_4 id: cognigyTtsBridgeReceiveKeepalive title: Cognigy tts bridge receive keepalive description: Send keepalive on Cognigy TTS Bridge type: receive messages: - &ref_10 id: KeepaliveMessage contentType: application/json payload: - name: Keepalive Message description: Keep the WebSocket connection alive during silence. type: object properties: - name: type type: string description: keepalive required: true headers: [] jsonPayloadSchema: type: object description: >- Prevents the connection from being closed due to inactivity. Send periodically during silence to maintain the session. required: - type properties: type: type: string const: keepalive x-parser-schema-id: x-parser-schema-id: title: Keepalive Message description: Keep the WebSocket connection alive during silence. example: |- { "type": "keepalive" } bindings: [] extensions: - id: x-parser-unique-object-id value: KeepaliveMessage bindings: [] extensions: *ref_0 - &ref_5 id: cognigyTtsBridgeSendConnect title: Cognigy tts bridge send connect description: Receive connect signal from Cognigy TTS Bridge type: send messages: - &ref_11 id: CognigyConnectMessage contentType: application/json payload: - name: Connect Message description: Connection established with audio format information. type: object properties: - name: type type: string description: connect required: true - name: data type: object description: Audio format configuration required: true properties: - name: sample_rate type: integer description: Audio sample rate in Hz. enumValues: - 8000 - 16000 - 22050 - 24000 - 32000 - 44100 - 48000 required: false - name: base64_encoding type: boolean description: Whether audio chunks are base64 encoded required: false headers: [] jsonPayloadSchema: type: object description: Connection established with audio format information. required: - type - data properties: type: type: string const: connect x-parser-schema-id: data: type: object description: Audio format configuration properties: sample_rate: type: integer description: Audio sample rate in Hz. enum: - 8000 - 16000 - 22050 - 24000 - 32000 - 44100 - 48000 x-parser-schema-id: SampleRate base64_encoding: type: boolean description: Whether audio chunks are base64 encoded x-parser-schema-id: x-parser-schema-id: x-parser-schema-id: title: Connect Message description: Connection established with audio format information. example: |- { "type": "connect", "data": { "sample_rate": 16000, "base64_encoding": true } } bindings: [] extensions: - id: x-parser-unique-object-id value: CognigyConnectMessage bindings: [] extensions: *ref_0 - &ref_6 id: cognigyTtsBridgeSendError title: Cognigy tts bridge send error description: Receive error from Cognigy TTS Bridge type: send messages: - &ref_12 id: CognigyTTSErrorResponse contentType: application/json payload: - name: Error Response (Cognigy TTS) description: Error occurred during Cognigy TTS synthesis. type: object properties: - name: type type: string description: error required: true - name: error type: string description: >- Error code. May be omitted when the upstream provider does not surface a discrete error code. required: false - name: message type: string description: Human-readable error description required: true headers: [] jsonPayloadSchema: type: object description: Error occurred during synthesis. required: - type - message properties: type: type: string const: error x-parser-schema-id: error: type: string description: >- Error code. May be omitted when the upstream provider does not surface a discrete error code. x-parser-schema-id: message: type: string description: Human-readable error description x-parser-schema-id: x-parser-schema-id: title: Error Response (Cognigy TTS) description: Error occurred during Cognigy TTS synthesis. example: |- { "type": "error", "error": "provider_error", "message": "TTS provider returned an error" } bindings: [] extensions: - id: x-parser-unique-object-id value: CognigyTTSErrorResponse bindings: [] extensions: *ref_0 sendOperations: - *ref_1 - *ref_2 - *ref_3 - *ref_4 receiveOperations: - *ref_5 - *ref_6 sendMessages: - *ref_7 - *ref_8 - *ref_9 - *ref_10 receiveMessages: - *ref_11 - *ref_12 extensions: - id: x-parser-unique-object-id value: /v1/bridges/cognigy/tts/{model_variant} securitySchemes: - id: bearer name: bearer type: http description: > API key issued by SLNG. Pass as `Authorization: Bearer ` in the WebSocket upgrade request headers. scheme: bearer extensions: [] ````