diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6106b84..b80dccd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 # Changelog
 
+## [4.41.6]
+
+- Expose `language_code` in `SyncTranscriptResponse` — surfaces the ISO 639-1 language code detected or used by the model for synchronous transcription requests (e.g. `"en"`, `"es"`; `undefined` for responses from older servers)
+- Expose `auth_time_ms` in `DictationResponse` — surfaces the authentication and token/API-key validation portion of `request_time_ms` for dictation requests (`undefined` when omitted by older servers)
+
 ## [4.41.5]
 
 - Add `speakerLabelsRevisionIntervalMs` streaming param (sent as `speaker_labels_revision_interval_ms`) — the cadence, in ms of audio time, at which the server emits mid-stream `speakerRevision` events when `speakerLabels` is enabled. Unset or `0` sends only the end-of-stream revision; non-zero values are clamped server-side to 120 000–300 000 ms. The first mid-stream revision needs ~120 s of streamed speech, and one is sent only when some earlier turn's label changed
diff --git a/CLAUDE.md b/CLAUDE.md
index 7946799..58f3794 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -371,7 +371,8 @@ afterwards. Over-cap prompts throw before the request is sent. There is no `mode
 timestamps), `confidence`, `llm_response` (`string | null`, the rewrite when the LLM pass ran),
 `llm_error` (`string | null`, why it failed when it did), `audio_duration_ms`, `session_id`
 (record it to correlate with support), and optional `request_time_ms` / `sync_time_ms`
-(transcription time excluding the LLM pass). **Show `final_text`** — derived by the SDK as
+(transcription time excluding the LLM pass) / `auth_time_ms` (auth portion of
+`request_time_ms`). **Show `final_text`** — derived by the SDK as
 `llm_response` when there is one, `text` otherwise, so it is safe to read either way.
 
 **Errors**: failures throw `DictationError` (a separate class from `SyncTranscriptError`) with
diff --git a/package.json b/package.json
index 8266741..944ab0a 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "assemblyai",
-  "version": "4.41.5",
+  "version": "4.41.6",
   "description": "The AssemblyAI JavaScript SDK provides an easy-to-use interface for interacting with the AssemblyAI API, which supports async and real-time transcription.",
   "engines": {
     "node": ">=18"
diff --git a/src/types/dictation/index.ts b/src/types/dictation/index.ts
index ffe6ce2..8bc38c0 100644
--- a/src/types/dictation/index.ts
+++ b/src/types/dictation/index.ts
@@ -140,6 +140,11 @@ export type DictationResponse = {
    * The time in milliseconds spent transcribing, excluding the LLM pass.
    */
   sync_time_ms?: number;
+  /**
+   * Authentication and key-validation time in milliseconds, as a portion of
+   * `request_time_ms`. `undefined` when the server predates the field.
+   */
+  auth_time_ms?: number;
   /**
    * The text to show the user: `llm_response` when the LLM pass produced one,
    * `text` otherwise. Derived by the SDK from those two fields, so reading it
diff --git a/src/types/sync/index.ts b/src/types/sync/index.ts
index 4196494..72c99a1 100644
--- a/src/types/sync/index.ts
+++ b/src/types/sync/index.ts
@@ -176,6 +176,14 @@ export type SyncTranscriptResponse = {
    * request with support.
    */
   session_id: string;
+  /**
+   * ISO 639-1 language code the model used for this transcript (e.g. `"en"`,
+   * `"es"`). Populated when the server detects or is told the language;
+   * `undefined` for responses from servers that predate the field. Useful
+   * when `language_codes` was not set and you need to know which language the
+   * model chose.
+   */
+  language_code?: string;
   /**
    * The end-to-end server-side request time in milliseconds. `undefined`
    * when the server predates the field.
diff --git a/tests/unit/dictation.test.ts b/tests/unit/dictation.test.ts
index 4f79627..f0c75c8 100644
--- a/tests/unit/dictation.test.ts
+++ b/tests/unit/dictation.test.ts
@@ -535,6 +535,22 @@ describe("dictation response", () => {
     expect(result.sync_time_ms).toBe(180.2);
   });
 
+  it("should parse auth_time_ms when present in the response", async () => {
+    mockOk({ ...okResponse, auth_time_ms: 24.6 });
+    const result = await assembly.dictation.transcribeLive(
+      chunks(bytes("RIFF")),
+    );
+    expect(result.auth_time_ms).toBe(24.6);
+  });
+
+  it("should leave auth_time_ms undefined when omitted by the server", async () => {
+    mockOk();
+    const result = await assembly.dictation.transcribeLive(
+      chunks(bytes("RIFF")),
+    );
+    expect(result.auth_time_ms).toBeUndefined();
+  });
+
   it("should prefer the LLM rewrite for final_text", async () => {
     mockOk({ ...okResponse, llm_response: "Take 2 tablets daily." });
     const result = await assembly.dictation.transcribeLive(
diff --git a/tests/unit/sync.test.ts b/tests/unit/sync.test.ts
index 491c331..2608d16 100644
--- a/tests/unit/sync.test.ts
+++ b/tests/unit/sync.test.ts
@@ -171,6 +171,22 @@ describe("sync", () => {
     expect(result.request_time_ms).toBeUndefined();
   });
 
+  it("should parse a response with language_code", async () => {
+    const response = { ...okResponse, language_code: "es" };
+    fetchMock.doMockOnceIf(
+      requestMatches({ url: liveUrl, method: "POST" }),
+      JSON.stringify(response),
+    );
+    const result = await assembly.sync.transcribe(fakeWavBytes);
+    expect(result.language_code).toBe("es");
+  });
+
+  it("should parse a response without language_code", async () => {
+    mockOk();
+    const result = await assembly.sync.transcribe(fakeWavBytes);
+    expect(result.language_code).toBeUndefined();
+  });
+
   it("should stream a chunked multipart body with the config part first", async () => {
     mockOk();
     await assembly.sync.transcribe(fakeWavBytes);