diff --git a/basedpyright-code-budget.json b/basedpyright-code-budget.json
index db49ae8f48b..3357212a6c8 100644
--- a/basedpyright-code-budget.json
+++ b/basedpyright-code-budget.json
@@ -99,7 +99,7 @@
     "limit": 0
   },
   "reportUnknownArgumentType": {
-    "limit": 44530
+    "limit": 44528
   },
   "reportUnknownLambdaType": {
     "limit": 109
@@ -138,9 +138,9 @@
     "limit": 139
   },
   "reportUnusedImport": {
-    "limit": 545
+    "limit": 544
   },
   "reportUnusedVariable": {
-    "limit": 146
+    "limit": 145
   }
 }
diff --git a/litellm/endpoints/speech/speech_to_completion_bridge/transformation.py b/litellm/endpoints/speech/speech_to_completion_bridge/transformation.py
index a9429b673e4..fb66edbf272 100644
--- a/litellm/endpoints/speech/speech_to_completion_bridge/transformation.py
+++ b/litellm/endpoints/speech/speech_to_completion_bridge/transformation.py
@@ -8,6 +8,14 @@ if TYPE_CHECKING:
     from litellm.types.utils import ModelResponse
 
 
+def _completion_response_cost(model_response: "ModelResponse") -> float | None:
+    hidden_params: Final = getattr(model_response, "_hidden_params", None)
+    if not isinstance(hidden_params, dict):
+        return None
+    response_cost: Final = hidden_params.get("response_cost")
+    return response_cost if isinstance(response_cost, float) else None
+
+
 class SpeechToCompletionBridgeTransformationHandler:
     def transform_request(
         self,
@@ -123,4 +131,6 @@ class SpeechToCompletionBridgeTransformationHandler:
 
         # Create an httpx.Response object
         response: Final = httpx.Response(status_code=200, content=binary_data, headers=headers)
-        return HttpxBinaryResponseContent(response)
+        binary_response: Final = HttpxBinaryResponseContent(response)
+        binary_response.set_response_cost(_completion_response_cost(model_response))
+        return binary_response
diff --git a/litellm/litellm_core_utils/litellm_logging.py b/litellm/litellm_core_utils/litellm_logging.py
index 626af7530a4..fd2200c59cc 100644
--- a/litellm/litellm_core_utils/litellm_logging.py
+++ b/litellm/litellm_core_utils/litellm_logging.py
@@ -1590,7 +1590,7 @@ class Logging(LiteLLMLoggingBaseClass):
         if transformed_result is not None:
             result = transformed_result
 
-        if isinstance(result, BaseModel) and hasattr(result, "_hidden_params"):
+        if isinstance(result, (BaseModel, HttpxBinaryResponseContent)) and hasattr(result, "_hidden_params"):
             hidden_params: Final = getattr(result, "_hidden_params", {})
             if (
                 "response_cost" in hidden_params and hidden_params["response_cost"] is not None
diff --git a/litellm/main.py b/litellm/main.py
index 98f92e50599..8ee102f5d07 100644
--- a/litellm/main.py
+++ b/litellm/main.py
@@ -8013,7 +8013,7 @@ def speech(
 
     if max_retries is None:
         max_retries = litellm.num_retries or openai.DEFAULT_MAX_RETRIES
-    litellm_params_dict: Final = get_litellm_params(**kwargs)
+    litellm_params_dict: Final = get_litellm_params(metadata=metadata, api_key=api_key or dynamic_api_key, **kwargs)
 
     # Get provider-specific text-to-speech config and map parameters
     text_to_speech_provider_config = ProviderConfigManager.get_provider_text_to_speech_config(
diff --git a/litellm/types/llms/openai.py b/litellm/types/llms/openai.py
index 4a6c4a5bbb5..45f6b5c55a9 100644
--- a/litellm/types/llms/openai.py
+++ b/litellm/types/llms/openai.py
@@ -107,7 +107,17 @@ EmbeddingInput = str | list[str]
 
 
 class HttpxBinaryResponseContent(_HttpxBinaryResponseContent):
-    _hidden_params: dict = {}
+    _hidden_params: dict
+
+    def __init__(self, response: httpx.Response) -> None:
+        super().__init__(response)
+        self._hidden_params = {}  # mutable-ok: mutable-dict contract shared with ModelResponse logging consumers
+
+    def set_response_cost(self, response_cost: float | None) -> None:
+        if response_cost is None:
+            self._hidden_params.pop("response_cost", None)
+            return
+        self._hidden_params["response_cost"] = response_cost
 
 
 class NotGiven:
diff --git a/ruff-strict-budget.json b/ruff-strict-budget.json
index b24335ad112..149c44ed083 100644
--- a/ruff-strict-budget.json
+++ b/ruff-strict-budget.json
@@ -108,7 +108,7 @@
     "limit": 3
   },
   "F401": {
-    "limit": 14
+    "limit": 13
   },
   "LOG015": {
     "limit": 5
@@ -171,7 +171,7 @@
     "limit": 175
   },
   "RUF012": {
-    "limit": 240
+    "limit": 239
   },
   "RUF015": {
     "limit": 8
@@ -183,7 +183,7 @@
     "limit": 4
   },
   "RUF059": {
-    "limit": 67
+    "limit": 66
   },
   "RUF100": {
     "limit": 0
diff --git a/tests/test_litellm/test_main.py b/tests/test_litellm/test_main.py
index 8f2b06be4b3..3eea47bcd5a 100644
--- a/tests/test_litellm/test_main.py
+++ b/tests/test_litellm/test_main.py
@@ -1,7 +1,12 @@
+import asyncio
+import base64
 import contextlib
 import copy
 import json
 import os
+from collections.abc import Mapping
+from dataclasses import dataclass
+from typing import Final
 
 import httpx
 import pytest
@@ -14,6 +19,9 @@ from unittest.mock import MagicMock, patch
 
 import litellm
 from litellm import main as litellm_main
+from litellm.integrations.custom_logger import CustomLogger
+from litellm.litellm_core_utils.core_helpers import get_litellm_metadata_from_kwargs
+from litellm.types.utils import Usage
 
 
 async def _async_fake_bedrock_image_details(image_url):
@@ -2957,3 +2965,109 @@ async def test_acompletion_resolves_provider_from_api_base():
     )
 
     assert response.choices[0].message.content == "resolved"
+
+
+@dataclass(frozen=True, slots=True)
+class _RecordedSpeechSuccess:
+    call_type: str | None
+    spend_metadata: Mapping[str, object]
+    response_cost: float | None
+    logged_response_cost: float | None
+
+
+def _record_speech_success(payload: dict[str, object]) -> _RecordedSpeechSuccess:
+    call_type: Final = payload.get("call_type")
+    response_cost: Final = payload.get("response_cost")
+    logging_payload: Final = payload.get("standard_logging_object")
+    logged_cost: Final = logging_payload.get("response_cost") if isinstance(logging_payload, dict) else None
+    return _RecordedSpeechSuccess(
+        call_type=call_type if isinstance(call_type, str) else None,
+        spend_metadata=get_litellm_metadata_from_kwargs(payload),
+        response_cost=response_cost if isinstance(response_cost, float) else None,
+        logged_response_cost=logged_cost if isinstance(logged_cost, float) else None,
+    )
+
+
+class _SuccessEventRecorder(CustomLogger):
+    def __init__(self) -> None:
+        super().__init__()
+        self.events: list[_RecordedSpeechSuccess] = []  # mutable-ok: test recorder of success-callback events
+
+    async def async_log_success_event(
+        self, kwargs: dict[str, object], response_obj: object, start_time: object, end_time: object
+    ) -> None:
+        self.events.append(_record_speech_success(kwargs))
+
+
+async def _wait_for_success_event(recorder: _SuccessEventRecorder, call_type: str) -> _RecordedSpeechSuccess:
+    for _ in range(100):
+        if (event := next((e for e in recorder.events if e.call_type == call_type), None)) is not None:
+            return event
+        await asyncio.sleep(0.05)
+    pytest.fail(f"no {call_type} success event; got {[e.call_type for e in recorder.events]}")
+
+
+def _gemini_tts_generate_content_response() -> dict[str, object]:
+    return {
+        "candidates": [
+            {
+                "content": {
+                    "parts": [
+                        {
+                            "inlineData": {
+                                "mimeType": "audio/L16;codec=pcm;rate=24000",
+                                "data": base64.b64encode(b"pcm-audio-bytes").decode(),
+                            }
+                        }
+                    ],
+                    "role": "model",
+                },
+                "finishReason": "STOP",
+                "index": 0,
+            }
+        ],
+        "usageMetadata": {
+            "promptTokenCount": 5,
+            "candidatesTokenCount": 60,
+            "totalTokenCount": 65,
+            "promptTokensDetails": [{"modality": "TEXT", "tokenCount": 5}],
+            "candidatesTokensDetails": [{"modality": "AUDIO", "tokenCount": 60}],
+        },
+        "modelVersion": "gemini-2.5-flash-preview-tts",
+    }
+
+
+@pytest.mark.asyncio
+async def test_aspeech_gemini_bridge_keeps_proxy_metadata_for_spend_tracking(
+    respx_mock: respx.MockRouter, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    monkeypatch.setattr(litellm, "disable_aiohttp_transport", True)
+    monkeypatch.delenv("GEMINI_API_KEY", raising=False)
+    monkeypatch.delenv("GOOGLE_API_KEY", raising=False)
+    recorder: Final = _SuccessEventRecorder()
+    monkeypatch.setattr(litellm, "callbacks", [recorder])
+    mock_route: Final = respx_mock.post(
+        url__regex=r"https://generativelanguage\.googleapis\.com/v1beta/models/gemini-2\.5-flash-preview-tts:generateContent.*"
+    ).mock(return_value=httpx.Response(200, json=_gemini_tts_generate_content_response()))
+
+    await litellm.aspeech(
+        model="gemini/gemini-2.5-flash-preview-tts",
+        input="spend tracking check",
+        voice="Kore",
+        api_key="fake-gemini-key",
+        metadata={"user_api_key": "hashed-virtual-key", "user_api_key_user_id": "user-1"},
+    )
+
+    assert mock_route.called
+    assert mock_route.calls.last.request.headers["x-goog-api-key"] == "fake-gemini-key"
+    speech_event: Final = await _wait_for_success_event(recorder, call_type="aspeech")
+    assert speech_event.spend_metadata["user_api_key"] == "hashed-virtual-key"
+    assert speech_event.spend_metadata["user_api_key_user_id"] == "user-1"
+    expected_prompt_cost, expected_completion_cost = litellm.cost_per_token(
+        model="gemini/gemini-2.5-flash-preview-tts",
+        usage_object=Usage(prompt_tokens=5, completion_tokens=60, total_tokens=65),
+    )
+    expected_cost: Final = expected_prompt_cost + expected_completion_cost
+    assert expected_cost > 0
+    assert speech_event.response_cost == pytest.approx(expected_cost)
+    assert speech_event.logged_response_cost == pytest.approx(expected_cost)
diff --git a/tests/test_litellm/types/llms/test_types_llms_openai.py b/tests/test_litellm/types/llms/test_types_llms_openai.py
index 3966677e928..42719ce838b 100644
--- a/tests/test_litellm/types/llms/test_types_llms_openai.py
+++ b/tests/test_litellm/types/llms/test_types_llms_openai.py
@@ -7,6 +7,7 @@ import pytest
 import json
 
 import litellm
+from litellm.types.llms.openai import HttpxBinaryResponseContent
 
 
 def test_generic_event():
@@ -522,3 +523,34 @@ class TestOpenAIFileObjectBatchGuardrailSerialization:
 
         page = FileListPage(object="list", data=[self._file_object()], has_more=False)
         assert "litellm_batch_guardrail" not in page.model_dump(mode="json")["data"][0]
+
+
+def _binary_content(payload: bytes) -> HttpxBinaryResponseContent:
+    import httpx
+
+    return HttpxBinaryResponseContent(httpx.Response(200, content=payload))
+
+
+def test_httpx_binary_response_content_hidden_params_are_per_instance():
+    first = _binary_content(b"first")
+    second = _binary_content(b"second")
+
+    first._hidden_params["response_cost"] = 0.5
+
+    assert second._hidden_params == {}
+
+
+def test_set_response_cost_none_leaves_hidden_params_empty():
+    binary_response = _binary_content(b"audio")
+
+    binary_response.set_response_cost(None)
+
+    assert "response_cost" not in binary_response._hidden_params
+
+    binary_response.set_response_cost(0.25)
+
+    assert binary_response._hidden_params["response_cost"] == 0.25
+
+    binary_response.set_response_cost(None)
+
+    assert "response_cost" not in binary_response._hidden_params