diff --git a/audio/aidl/default/include/core-impl/Module.h b/audio/aidl/default/include/core-impl/Module.h
index 83ecfaa..e8b3d89 100644
--- a/audio/aidl/default/include/core-impl/Module.h
+++ b/audio/aidl/default/include/core-impl/Module.h
@@ -39,33 +39,9 @@
     static StreamIn::CreateInstance getStreamInCreator(Type type);
     static StreamOut::CreateInstance getStreamOutCreator(Type type);
 
-  private:
-    struct VendorDebug {
-        static const std::string kForceTransientBurstName;
-        static const std::string kForceSynchronousDrainName;
-        bool forceTransientBurst = false;
-        bool forceSynchronousDrain = false;
-    };
-    // Helper used for interfaces that require a persistent instance. We hold them via a strong
-    // pointer. The binder token is retained for a call to 'setMinSchedulerPolicy'.
-    template <class C>
-    struct ChildInterface : private std::pair<std::shared_ptr<C>, ndk::SpAIBinder> {
-        ChildInterface() {}
-        ChildInterface& operator=(const std::shared_ptr<C>& c) {
-            return operator=(std::shared_ptr<C>(c));
-        }
-        ChildInterface& operator=(std::shared_ptr<C>&& c) {
-            this->first = std::move(c);
-            this->second = this->first->asBinder();
-            AIBinder_setMinSchedulerPolicy(this->second.get(), SCHED_NORMAL,
-                                           ANDROID_PRIORITY_AUDIO);
-            return *this;
-        }
-        explicit operator bool() const { return !!this->first; }
-        C& operator*() const { return *(this->first); }
-        C* operator->() const { return this->first; }
-        std::shared_ptr<C> getPtr() const { return this->first; }
-    };
+  protected:
+    // The vendor extension done via inheritance can override interface methods and augment
+    // a call to the base implementation.
 
     ndk::ScopedAStatus setModuleDebug(
             const ::aidl::android::hardware::audio::core::ModuleDebug& in_debug) override;
@@ -146,29 +122,46 @@
     ndk::ScopedAStatus getAAudioMixerBurstCount(int32_t* _aidl_return) override;
     ndk::ScopedAStatus getAAudioHardwareBurstMinUsec(int32_t* _aidl_return) override;
 
-    void cleanUpPatch(int32_t patchId);
-    ndk::ScopedAStatus createStreamContext(
-            int32_t in_portConfigId, int64_t in_bufferSizeFrames,
-            std::shared_ptr<IStreamCallback> asyncCallback,
-            std::shared_ptr<IStreamOutEventCallback> outEventCallback,
-            ::aidl::android::hardware::audio::core::StreamContext* out_context);
-    std::vector<::aidl::android::media::audio::common::AudioDevice> findConnectedDevices(
-            int32_t portConfigId);
-    std::set<int32_t> findConnectedPortConfigIds(int32_t portConfigId);
-    ndk::ScopedAStatus findPortIdForNewStream(
-            int32_t in_portConfigId, ::aidl::android::media::audio::common::AudioPort** port);
-    internal::Configuration& getConfig();
-    template <typename C>
-    std::set<int32_t> portIdsFromPortConfigIds(C portConfigIds);
-    void registerPatch(const AudioPatch& patch);
-    void updateStreamsConnectedState(const AudioPatch& oldPatch, const AudioPatch& newPatch);
-    bool isMmapSupported();
-
     // This value is used for all AudioPatches.
     static constexpr int32_t kMinimumStreamBufferSizeFrames = 256;
     // The maximum stream buffer size is 1 GiB = 2 ** 30 bytes;
     static constexpr int32_t kMaximumStreamBufferSizeBytes = 1 << 30;
 
+  private:
+    struct VendorDebug {
+        static const std::string kForceTransientBurstName;
+        static const std::string kForceSynchronousDrainName;
+        bool forceTransientBurst = false;
+        bool forceSynchronousDrain = false;
+    };
+    // Helper used for interfaces that require a persistent instance. We hold them via a strong
+    // pointer. The binder token is retained for a call to 'setMinSchedulerPolicy'.
+    template <class C>
+    struct ChildInterface : private std::pair<std::shared_ptr<C>, ndk::SpAIBinder> {
+        ChildInterface() {}
+        ChildInterface& operator=(const std::shared_ptr<C>& c) {
+            return operator=(std::shared_ptr<C>(c));
+        }
+        ChildInterface& operator=(std::shared_ptr<C>&& c) {
+            this->first = std::move(c);
+            this->second = this->first->asBinder();
+            AIBinder_setMinSchedulerPolicy(this->second.get(), SCHED_NORMAL,
+                                           ANDROID_PRIORITY_AUDIO);
+            return *this;
+        }
+        explicit operator bool() const { return !!this->first; }
+        C& operator*() const { return *(this->first); }
+        C* operator->() const { return this->first; }
+        std::shared_ptr<C> getPtr() const { return this->first; }
+    };
+    // ids of device ports created at runtime via 'connectExternalDevice'.
+    // Also stores a list of ids of mix ports with dynamic profiles that were populated from
+    // the connected port. This list can be empty, thus an int->int multimap can't be used.
+    using ConnectedDevicePorts = std::map<int32_t, std::vector<int32_t>>;
+    // Maps port ids and port config ids to patch ids.
+    // Multimap because both ports and configs can be used by multiple patches.
+    using Patches = std::multimap<int32_t, int32_t>;
+
     const Type mType;
     std::unique_ptr<internal::Configuration> mConfig;
     ModuleDebug mDebug;
@@ -177,19 +170,18 @@
     ChildInterface<IBluetooth> mBluetooth;
     ChildInterface<IBluetoothA2dp> mBluetoothA2dp;
     ChildInterface<IBluetoothLe> mBluetoothLe;
-    // ids of device ports created at runtime via 'connectExternalDevice'.
-    // Also stores ids of mix ports with dynamic profiles which got populated from the connected
-    // port.
-    std::map<int32_t, std::vector<int32_t>> mConnectedDevicePorts;
+    ConnectedDevicePorts mConnectedDevicePorts;
     Streams mStreams;
-    // Maps port ids and port config ids to patch ids.
-    // Multimap because both ports and configs can be used by multiple patches.
-    std::multimap<int32_t, int32_t> mPatches;
+    Patches mPatches;
     bool mMicMute = false;
+    bool mMasterMute = false;
+    float mMasterVolume = 1.0f;
     ChildInterface<sounddose::ISoundDose> mSoundDose;
     std::optional<bool> mIsMmapSupported;
 
   protected:
+    // The following virtual functions are intended for vendor extension via inheritance.
+
     // If the module is unable to populate the connected device port correctly, the returned error
     // code must correspond to the errors of `IModule.connectedExternalDevice` method.
     virtual ndk::ScopedAStatus populateConnectedDevicePort(
@@ -204,8 +196,30 @@
     virtual ndk::ScopedAStatus onMasterMuteChanged(bool mute);
     virtual ndk::ScopedAStatus onMasterVolumeChanged(float volume);
 
-    bool mMasterMute = false;
-    float mMasterVolume = 1.0f;
+    // Utility and helper functions accessible to subclasses.
+    void cleanUpPatch(int32_t patchId);
+    ndk::ScopedAStatus createStreamContext(
+            int32_t in_portConfigId, int64_t in_bufferSizeFrames,
+            std::shared_ptr<IStreamCallback> asyncCallback,
+            std::shared_ptr<IStreamOutEventCallback> outEventCallback,
+            ::aidl::android::hardware::audio::core::StreamContext* out_context);
+    std::vector<::aidl::android::media::audio::common::AudioDevice> findConnectedDevices(
+            int32_t portConfigId);
+    std::set<int32_t> findConnectedPortConfigIds(int32_t portConfigId);
+    ndk::ScopedAStatus findPortIdForNewStream(
+            int32_t in_portConfigId, ::aidl::android::media::audio::common::AudioPort** port);
+    internal::Configuration& getConfig();
+    const ConnectedDevicePorts& getConnectedDevicePorts() const { return mConnectedDevicePorts; }
+    bool getMasterMute() const { return mMasterMute; }
+    bool getMasterVolume() const { return mMasterVolume; }
+    bool getMicMute() const { return mMicMute; }
+    const Patches& getPatches() const { return mPatches; }
+    const Streams& getStreams() const { return mStreams; }
+    bool isMmapSupported();
+    template <typename C>
+    std::set<int32_t> portIdsFromPortConfigIds(C portConfigIds);
+    void registerPatch(const AudioPatch& patch);
+    void updateStreamsConnectedState(const AudioPatch& oldPatch, const AudioPatch& newPatch);
 };
 
 }  // namespace aidl::android::hardware::audio::core
diff --git a/audio/aidl/default/usb/ModuleUsb.cpp b/audio/aidl/default/usb/ModuleUsb.cpp
index 28116ae..c568dc9 100644
--- a/audio/aidl/default/usb/ModuleUsb.cpp
+++ b/audio/aidl/default/usb/ModuleUsb.cpp
@@ -175,8 +175,8 @@
         return;
     }
     const int card = address.get<AudioDeviceAddress::alsa>()[0];
-    usb::UsbAlsaMixerControl::getInstance().setDeviceConnectionState(card, mMasterMute,
-                                                                     mMasterVolume, connected);
+    usb::UsbAlsaMixerControl::getInstance().setDeviceConnectionState(card, getMasterMute(),
+                                                                     getMasterVolume(), connected);
 }
 
 ndk::ScopedAStatus ModuleUsb::onMasterMuteChanged(bool mute) {