diff --git a/vocero-api/CHANGELOG.md b/vocero-api/CHANGELOG.md
index 2c9809f..bcf6f1f 100644
--- a/vocero-api/CHANGELOG.md
+++ b/vocero-api/CHANGELOG.md
@@ -9,6 +9,9 @@ the implementation at the recorded date; current operating instructions live in
 
 ### Fixed
 
+- Isolate microphone meter subscriptions from the application tree. Apply draft settings only
+  on Save, preserve explicitly live noise calibration, and persist/send only relevant changes.
+
 - Keep the voice UI speaking until buffered playback finishes, flush short final audio chunks,
   and exclude response processing from the user inactivity timeout.
 
diff --git a/vocero-frontend/src/App.test.tsx b/vocero-frontend/src/App.test.tsx
index 36b94d1..68df72c 100644
--- a/vocero-frontend/src/App.test.tsx
+++ b/vocero-frontend/src/App.test.tsx
@@ -62,8 +62,9 @@ describe("React application", () => {
     await user.click(await screen.findByRole("button", { name: "Configuración" }));
     expect(document.documentElement.dataset.theme).toBe("white");
     await user.selectOptions(screen.getByRole("combobox"), "Serena");
-    expect(localStorage.getItem("s2s.ws.voice")).toBe("Serena");
+    expect(localStorage.getItem("s2s.ws.voice")).toBeNull();
     await user.click(screen.getByRole("button", { name: "Guardar" }));
+    expect(localStorage.getItem("s2s.ws.voice")).toBe("Serena");
     expect(screen.queryByRole("dialog")).not.toBeInTheDocument();
     view.unmount();
     render(
@@ -74,6 +75,19 @@ describe("React application", () => {
     await user.click(await screen.findByRole("button", { name: "Configuración" }));
     expect(screen.getByRole("combobox")).toHaveValue("Serena");
   });
+  it("discards unsaved settings on cancel while keeping live noise-gate calibration", async () => {
+    const user = userEvent.setup();
+    render(<App />);
+    await user.click(await screen.findByRole("button", { name: "Configuración" }));
+    await user.selectOptions(screen.getByRole("combobox"), "Serena");
+    fireEvent.change(screen.getByRole("slider"), { target: { value: "-35" } });
+    await user.click(screen.getByRole("button", { name: "Cancelar" }));
+    await user.click(screen.getByRole("button", { name: "Configuración" }));
+    expect(screen.getByRole("combobox")).toHaveValue("Aiden");
+    expect(screen.getByRole("slider")).toHaveValue("-35");
+    expect(localStorage.getItem("s2s.ws.voice")).toBeNull();
+    expect(localStorage.getItem("s2s.ws.noiseGate")).toBe("-35");
+  });
   it("saves and clears session-only RAG context and supports keyboard dialog dismissal", async () => {
     const user = userEvent.setup();
     render(<App />);
diff --git a/vocero-frontend/src/components/SettingsDialogs.tsx b/vocero-frontend/src/components/SettingsDialogs.tsx
index 964ca4f..bf66569 100644
--- a/vocero-frontend/src/components/SettingsDialogs.tsx
+++ b/vocero-frontend/src/components/SettingsDialogs.tsx
@@ -1,4 +1,4 @@
-import { useState } from "react";
+import { useState, useSyncExternalStore } from "react";
 
 import { initials, profileName } from "../lib/context";
 import { profileRows } from "../lib/profile";
@@ -13,15 +13,17 @@ interface Props {
 }
 export function SettingsDialog({ state, controller, onClose }: Props) {
   const { config, settings } = state;
-  const meter = Math.max(
-    0,
-    Math.min(100, ((20 * Math.log10(state.level || 0.00001) - GATE_OFF) * 100) / (GATE_MAX - GATE_OFF)),
-  );
+  const [draft, setDraft] = useState(() => ({
+    directUrl: settings.directUrl,
+    voice: settings.voice,
+    instructions: settings.instructions,
+  }));
   return (
     <Dialog title="Configuración" onClose={onClose}>
       <form
         onSubmit={(event) => {
           event.preventDefault();
+          controller.changeSettings(draft);
           onClose();
         }}
       >
@@ -35,10 +37,10 @@ export function SettingsDialog({ state, controller, onClose }: Props) {
                   autoComplete="off"
                   spellCheck={false}
                   placeholder="http://localhost:8080"
-                  value={config.s2sUrl || settings.directUrl}
+                  value={config.s2sUrl || draft.directUrl}
                   readOnly={!!config.s2sUrl}
                   onChange={(event) => {
-                    controller.changeSettings({ directUrl: event.target.value });
+                    setDraft({ ...draft, directUrl: event.target.value });
                   }}
                 />
                 <small>
@@ -52,9 +54,9 @@ export function SettingsDialog({ state, controller, onClose }: Props) {
               <label className="field">
                 <span>Voz</span>
                 <select
-                  value={settings.voice}
+                  value={draft.voice}
                   onChange={(event) => {
-                    controller.changeSettings({ voice: event.target.value });
+                    setDraft({ ...draft, voice: event.target.value });
                   }}
                 >
                   {VOICES.map((voice) => (
@@ -72,7 +74,7 @@ export function SettingsDialog({ state, controller, onClose }: Props) {
               </label>
               <div className="gate">
                 <div className="gate-track">
-                  <div className="gate-meter-fill" style={{ width: `${String(meter)}%` }} aria-hidden="true" />
+                  <GateMeter controller={controller} />
                   <input
                     id="noise-gate"
                     aria-label="Umbral de la puerta de ruido"
@@ -92,18 +94,18 @@ export function SettingsDialog({ state, controller, onClose }: Props) {
                 </div>
               </div>
               <small>
-                Silencia el micrófono por debajo del umbral para evitar enviar ruido. Desliza hasta la izquierda para
-                desactivarla.
+                Se aplica y guarda al instante. Silencia el micrófono por debajo del umbral. Desliza hasta la izquierda
+                para desactivarla.
               </small>
             </div>
             <label className="field">
               <span>Instrucciones</span>
               <textarea
                 rows={5}
-                value={config.primaryPrompt || settings.instructions}
+                value={config.primaryPrompt || draft.instructions}
                 readOnly={!!config.primaryPrompt}
                 onChange={(event) => {
-                  controller.changeSettings({ instructions: event.target.value });
+                  setDraft({ ...draft, instructions: event.target.value });
                 }}
               />
               {config.primaryPrompt && <small>Las instrucciones están definidas por el servidor.</small>}
@@ -114,17 +116,24 @@ export function SettingsDialog({ state, controller, onClose }: Props) {
                 className="btn primary wide"
                 disabled={!LIVE_STATES.has(state.status)}
                 onClick={() => {
+                  controller.changeSettings(draft);
                   onClose();
                   void controller.restart();
                 }}
               >
                 Reiniciar conversación con esta configuración
               </button>
-              <small>La voz, las instrucciones y la puerta de ruido se actualizan en la sesión actual.</small>
+              <small>
+                Al guardar, la voz y las instrucciones se aplican a la sesión actual. Los cambios de servidor requieren
+                una nueva conversación.
+              </small>
             </div>
           </div>
         </div>
         <footer className="modal-footer">
+          <button className="btn secondary" type="button" onClick={onClose}>
+            Cancelar
+          </button>
           <button className="btn primary" type="submit">
             Guardar
           </button>
@@ -134,6 +143,15 @@ export function SettingsDialog({ state, controller, onClose }: Props) {
   );
 }
 
+function GateMeter({ controller }: { controller: VoiceController }) {
+  const level = useSyncExternalStore(controller.subscribeLevel, controller.getLevel);
+  const meter = Math.max(
+    0,
+    Math.min(100, ((20 * Math.log10(level || 0.00001) - GATE_OFF) * 100) / (GATE_MAX - GATE_OFF)),
+  );
+  return <div className="gate-meter-fill" style={{ width: `${String(meter)}%` }} aria-hidden="true" />;
+}
+
 export function RagDialog({ state, controller, onClose }: Props) {
   const [text, setText] = useState(state.rag);
   const [saved, setSaved] = useState(false);
@@ -193,69 +211,89 @@ export function RagDialog({ state, controller, onClose }: Props) {
 }
 
 export function ToolsDialog({ state, controller, onClose }: Props) {
+  const [draft, setDraft] = useState(() => ({
+    webSearch: state.settings.webSearch,
+    searchKey: state.settings.searchKey,
+  }));
   return (
     <Dialog title="Herramientas" onClose={onClose}>
       <p className="tools-intro">
-        Permite que el asistente actúe durante la conversación. Los cambios se aplican de inmediato.
+        Permite que el asistente actúe durante la conversación. Los cambios se aplican al guardar.
       </p>
-      <div className="tool-list">
-        <div className="tool-row">
-          <div className="tool-info">
-            <span className="tool-name">Búsqueda web</span>
-            <span className="tool-desc">Busca información en Google mediante Serper.</span>
+      <form
+        onSubmit={(event) => {
+          event.preventDefault();
+          controller.changeSettings(draft);
+          onClose();
+        }}
+      >
+        <div className="tool-list">
+          <div className="tool-row">
+            <div className="tool-info">
+              <span className="tool-name">Búsqueda web</span>
+              <span className="tool-desc">Busca información en Google mediante Serper.</span>
+            </div>
+            <label className="switch">
+              <input
+                type="checkbox"
+                aria-label="Búsqueda web"
+                checked={draft.webSearch}
+                onChange={(event) => {
+                  setDraft({ ...draft, webSearch: event.target.checked });
+                }}
+              />
+              <span className="switch-track" aria-hidden="true" />
+            </label>
           </div>
-          <label className="switch">
+          <label className="field tools-key">
+            <span>Clave de la API de búsqueda</span>
             <input
-              type="checkbox"
-              aria-label="Búsqueda web"
-              checked={state.settings.webSearch}
+              type="password"
+              autoComplete="off"
+              value={draft.searchKey}
+              disabled={state.config.search}
               onChange={(event) => {
-                controller.changeSettings({ webSearch: event.target.checked });
+                setDraft({ ...draft, searchKey: event.target.value });
               }}
             />
-            <span className="switch-track" aria-hidden="true" />
+            <small>
+              {state.config.search
+                ? "La búsqueda está configurada en el servidor."
+                : "Introduce tu clave de Serper para activar la búsqueda. Se guarda en este navegador."}
+            </small>
           </label>
-        </div>
-        <label className="field tools-key">
-          <span>Clave de la API de búsqueda</span>
-          <input
-            type="password"
-            autoComplete="off"
-            value={state.settings.searchKey}
-            disabled={state.config.search}
-            onChange={(event) => {
-              controller.changeSettings({ searchKey: event.target.value });
-            }}
-          />
-          <small>
-            {state.config.search
-              ? "La búsqueda está configurada en el servidor."
-              : "Introduce tu clave de Serper para activar la búsqueda. Se guarda en este navegador."}
-          </small>
-        </label>
-        <div className="tool-row tool-row-sep">
-          <div className="tool-info">
-            <span className="tool-name">Herramientas MCP cargadas</span>
-            <span className="tool-desc">Herramientas publicadas por el perfil remoto del agente.</span>
+          <div className="tool-row tool-row-sep">
+            <div className="tool-info">
+              <span className="tool-name">Herramientas MCP cargadas</span>
+              <span className="tool-desc">Herramientas publicadas por el perfil remoto del agente.</span>
+            </div>
+          </div>
+          <p className="tool-hint" role="status">
+            {state.toolsLoading
+              ? "Cargando herramientas…"
+              : state.toolsError ||
+                (state.tools.length
+                  ? `${String(state.tools.length)} herramientas disponibles.`
+                  : "No hay herramientas remotas disponibles.")}
+          </p>
+          <div className="agent-tools-list">
+            {state.tools.map((tool) => (
+              <article key={tool.name} className="agent-tool-item">
+                <strong className="block text-sm">{tool.name}</strong>
+                <p className="mt-1 text-sm opacity-75">{tool.description}</p>
+              </article>
+            ))}
           </div>
         </div>
-        <p className="tool-hint" role="status">
-          {state.toolsLoading
-            ? "Cargando herramientas…"
-            : state.toolsError ||
-              (state.tools.length
-                ? `${String(state.tools.length)} herramientas disponibles.`
-                : "No hay herramientas remotas disponibles.")}
-        </p>
-        <div className="agent-tools-list">
-          {state.tools.map((tool) => (
-            <article key={tool.name} className="agent-tool-item">
-              <strong className="block text-sm">{tool.name}</strong>
-              <p className="mt-1 text-sm opacity-75">{tool.description}</p>
-            </article>
-          ))}
-        </div>
-      </div>
+        <footer className="modal-footer">
+          <button className="btn secondary" type="button" onClick={onClose}>
+            Cancelar
+          </button>
+          <button className="btn primary" type="submit">
+            Guardar
+          </button>
+        </footer>
+      </form>
     </Dialog>
   );
 }
diff --git a/vocero-frontend/src/components/VoiceStage.tsx b/vocero-frontend/src/components/VoiceStage.tsx
index 098e764..65c9383 100644
--- a/vocero-frontend/src/components/VoiceStage.tsx
+++ b/vocero-frontend/src/components/VoiceStage.tsx
@@ -1,5 +1,5 @@
 import { CircleAlert, Mic, MicOff, Square, Volume2 } from "lucide-react";
-import { useEffect, useState, type CSSProperties, type PointerEvent } from "react";
+import { useEffect, useState, useSyncExternalStore, type CSSProperties, type PointerEvent } from "react";
 
 import type { ConnectionStatus } from "../lib/contracts";
 import { GATE_MAX, GATE_OFF } from "../lib/settings";
@@ -98,6 +98,45 @@ function Waveform({ side }: { side: "left" | "right" }) {
     </div>
   );
 }
+function MicrophoneGate({
+  controller,
+  threshold,
+  muted,
+  live,
+}: {
+  controller: VoiceController;
+  threshold: number;
+  muted: boolean;
+  live: boolean;
+}) {
+  const level = useSyncExternalStore(controller.subscribeLevel, controller.getLevel);
+  return (
+    <div className={`mic-gate ${20 * Math.log10(level || 0.00001) >= threshold ? "gate-open" : ""}`}>
+      {live && (
+        <GateArc
+          threshold={threshold}
+          level={level}
+          onChange={(noiseGate) => {
+            controller.changeSettings({ noiseGate });
+          }}
+        />
+      )}
+      <button
+        className={`side-btn ${muted ? "muted" : ""}`}
+        type="button"
+        disabled={!live}
+        tabIndex={live ? 0 : -1}
+        aria-label={muted ? "Activar micrófono" : "Silenciar micrófono"}
+        aria-pressed={muted}
+        onClick={() => {
+          controller.toggleMuted();
+        }}
+      >
+        {muted ? <MicOff /> : <Mic />}
+      </button>
+    </div>
+  );
+}
 function JoinCountdown({ deadline }: { deadline: number }) {
   const [now, setNow] = useState(Date.now);
   useEffect(() => {
@@ -195,32 +234,12 @@ export function VoiceStage({ state, controller }: { state: AppState; controller:
       ) : (
         <>
           <div className={`orb-wrap ${active ? "live" : ""}`}>
-            <div
-              className={`mic-gate ${20 * Math.log10(state.level || 0.00001) >= state.settings.noiseGate ? "gate-open" : ""}`}
-            >
-              {live && (
-                <GateArc
-                  threshold={state.settings.noiseGate}
-                  level={state.level}
-                  onChange={(noiseGate) => {
-                    controller.changeSettings({ noiseGate });
-                  }}
-                />
-              )}
-              <button
-                className={`side-btn ${state.muted ? "muted" : ""}`}
-                type="button"
-                disabled={!live}
-                tabIndex={live ? 0 : -1}
-                aria-label={muteLabel}
-                aria-pressed={state.muted}
-                onClick={() => {
-                  controller.toggleMuted();
-                }}
-              >
-                {state.muted ? <MicOff /> : <Mic />}
-              </button>
-            </div>
+            <MicrophoneGate
+              controller={controller}
+              threshold={state.settings.noiseGate}
+              muted={state.muted}
+              live={live}
+            />
             <button
               id="main-circle"
               className={`circle state-${status}`}
diff --git a/vocero-frontend/src/lib/settings.ts b/vocero-frontend/src/lib/settings.ts
index 56466bb..bd6b95b 100644
--- a/vocero-frontend/src/lib/settings.ts
+++ b/vocero-frontend/src/lib/settings.ts
@@ -40,12 +40,16 @@ export function loadSettings(): Settings {
     searchKey: read("searchKey") ?? "",
   };
 }
-export function saveSettings(settings: Settings) {
+export function saveSettings(settings: Partial<Settings>) {
   try {
     for (const key of ["directUrl", "voice", "instructions", "noiseGate", "searchKey"] as const) {
-      localStorage.setItem(`s2s.ws.${key}`, String(settings[key]));
+      if (settings[key] !== undefined) {
+        localStorage.setItem(`s2s.ws.${key}`, String(settings[key]));
+      }
+    }
+    if (settings.webSearch !== undefined) {
+      localStorage.setItem("s2s.ws.tools", JSON.stringify({ web_search: settings.webSearch }));
     }
-    localStorage.setItem("s2s.ws.tools", JSON.stringify({ web_search: settings.webSearch }));
   } catch {
     /* The current session still works when browser storage is disabled. */
   }
diff --git a/vocero-frontend/src/realtime/controller.test.ts b/vocero-frontend/src/realtime/controller.test.ts
index 3512bc4..da557a5 100644
--- a/vocero-frontend/src/realtime/controller.test.ts
+++ b/vocero-frontend/src/realtime/controller.test.ts
@@ -87,6 +87,32 @@ async function start() {
   return client;
 }
 describe("voice application lifecycle", () => {
+  it("notifies only meter subscribers when microphone level changes", async () => {
+    const client = await start();
+    const app = vi.fn();
+    const meter = vi.fn();
+    controller.subscribe(app);
+    controller.subscribeLevel(meter);
+    const snapshot = controller.getSnapshot();
+    client.emit("level", 0.2);
+    expect(controller.getLevel()).toBe(0.2);
+    expect(meter).toHaveBeenCalledOnce();
+    expect(app).not.toHaveBeenCalled();
+    expect(controller.getSnapshot()).toBe(snapshot);
+  });
+  it("saves only changed preferences and keeps noise calibration out of session updates", async () => {
+    const client = await start();
+    const save = vi.spyOn(Storage.prototype, "setItem");
+    client.updateSession.mockClear();
+    controller.changeSettings({ noiseGate: -35 });
+    expect(save).toHaveBeenCalledExactlyOnceWith("s2s.ws.noiseGate", "-35");
+    expect(client.setGate).toHaveBeenCalledExactlyOnceWith({ enabled: true, thresholdDb: -35 });
+    expect(client.updateSession).not.toHaveBeenCalled();
+    controller.changeSettings({ voice: "Serena", instructions: "New instructions" });
+    expect(client.updateSession).toHaveBeenCalledOnce();
+    controller.changeSettings({ voice: "Serena", instructions: "New instructions" });
+    expect(client.updateSession).toHaveBeenCalledOnce();
+  });
   it("renders configuration and starts without waiting for optional reports", async () => {
     const original = fetchMock.getMockImplementation();
     if (!original) {
diff --git a/vocero-frontend/src/realtime/controller.ts b/vocero-frontend/src/realtime/controller.ts
index 43e4328..4c6ef3a 100644
--- a/vocero-frontend/src/realtime/controller.ts
+++ b/vocero-frontend/src/realtime/controller.ts
@@ -53,7 +53,6 @@ export interface AppState {
   notice: string;
   messages: Message[];
   muted: boolean;
-  level: number;
   rag: string;
   queuePosition: number;
   joinDeadline: number;
@@ -65,6 +64,8 @@ export class VoiceController {
   readonly caller: Caller;
   private state: AppState;
   private readonly listeners = new Set<() => void>();
+  private readonly levelListeners = new Set<() => void>();
+  private level = 0;
   private client: RealtimeClient | null = null;
   private subscriptions: (() => void)[] = [];
   private requests = new AbortController();
@@ -98,7 +99,6 @@ export class VoiceController {
       notice: "",
       messages: [],
       muted: false,
-      level: 0,
       rag: "",
       queuePosition: 0,
       joinDeadline: 0,
@@ -106,6 +106,22 @@ export class VoiceController {
     };
   }
   getSnapshot = () => this.state;
+  getLevel = () => this.level;
+  subscribeLevel = (listener: () => void) => {
+    this.levelListeners.add(listener);
+    return () => {
+      this.levelListeners.delete(listener);
+    };
+  };
+  private updateLevel(level: number) {
+    if (this.level === level) {
+      return;
+    }
+    this.level = level;
+    this.levelListeners.forEach((listener) => {
+      listener();
+    });
+  }
   subscribe = (listener: () => void) => {
     this.listeners.add(listener);
     return () => {
@@ -215,13 +231,28 @@ export class VoiceController {
       this.state.settings.voice,
       this.tools(),
     );
-    this.client?.setGate(this.gate());
   }
   changeSettings(patch: Partial<Settings>) {
-    const settings = { ...this.state.settings, ...patch };
+    const changed = Object.fromEntries(
+      Object.entries(patch).filter(([key, value]) => this.state.settings[key as keyof Settings] !== value),
+    ) as Partial<Settings>;
+    if (!Object.keys(changed).length) {
+      return;
+    }
+    const settings = { ...this.state.settings, ...changed };
     this.update({ settings });
-    saveSettings(settings);
-    this.pushSettings();
+    saveSettings(changed);
+    if (changed.noiseGate !== undefined) {
+      this.client?.setGate(this.gate());
+    }
+    if (
+      changed.voice !== undefined ||
+      changed.instructions !== undefined ||
+      changed.webSearch !== undefined ||
+      changed.searchKey !== undefined
+    ) {
+      this.pushSettings();
+    }
   }
   setRag(rag: string) {
     this.update({ rag: rag.trim() });
@@ -338,7 +369,7 @@ export class VoiceController {
           }
           if (Date.now() - this.lastMeter > 150) {
             this.lastMeter = Date.now();
-            this.update({ level });
+            this.updateLevel(level);
           }
         }),
         client.on("queue", ({ position }) => {
@@ -574,10 +605,10 @@ export class VoiceController {
     this.requests.abort();
     this.cancelReasoning();
     window.speechSynthesis?.cancel();
+    this.updateLevel(0);
     this.update({
       status,
       muted: false,
-      level: 0,
       joinDeadline: 0,
       unlock: false,
       messages: this.state.messages.map((message) =>