# Host audio controls

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The controls in this topic have an effect only when the local user is the session host. Check `isHost` before exposing host controls in your UI. For the basic controls available to every user, see [Core features](/docs/video-sdk/linux/audio/).

```cpp
bool isHost = m_pVideoSDK->getSessionInfo()->getMyself()->isHost();
```

## Ask a single user to unmute

When the local user is the host, calling `unMuteAudio` on a remote user does not unmute them directly. It sends an unmute request. The target user's app receives the `onHostAskUnmute` callback and is responsible for prompting the user before calling `unMuteAudio` on themselves.

```cpp
// Host sends the request.
IZoomVideoSDKAudioHelper* pAudioHelper = m_pVideoSDK->getAudioHelper();
if (pAudioHelper) {
    pAudioHelper->unMuteAudio(pRemoteUser);
}
```

On the target user's device, implement `onHostAskUnmute`.

```cpp
void CExampleListener::onHostAskUnmute()
{
    // Show a dialog asking the user to unmute, then call:
    // IZoomVideoSDKUser* pMyself = m_pVideoSDK->getSessionInfo()->getMyself();
    // m_pVideoSDK->getAudioHelper()->unMuteAudio(pMyself);
}
```

## Mute or unmute everyone

The host can mute every participant at once with `muteAllAudio`. Passing `true` lets participants unmute themselves afterward; passing `false` keeps them muted until the host unmutes them or grants self-unmute with `allowAudioUnmutedBySelf`.

```cpp
IZoomVideoSDKAudioHelper* pAudioHelper = m_pVideoSDK->getAudioHelper();

// Mute everyone but let them unmute themselves later.
pAudioHelper->muteAllAudio(true);

// Mute everyone and prevent self-unmute.
pAudioHelper->muteAllAudio(false);
```

To request unmute from every participant (each user still has to accept on their device via `onHostAskUnmute`), call `unMuteAllAudio`.

```cpp
m_pVideoSDK->getAudioHelper()->unMuteAllAudio();
```

Toggle whether participants can unmute themselves at any time with `allowAudioUnmutedBySelf`.

```cpp
IZoomVideoSDKAudioHelper* pAudioHelper = m_pVideoSDK->getAudioHelper();

// Allow self-unmute.
pAudioHelper->allowAudioUnmutedBySelf(true);

// Block self-unmute.
pAudioHelper->allowAudioUnmutedBySelf(false);
```