# Using 2-Way Audio

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Nx Witness allows playing sound directly on devices (Cameras or I/O Modules). It can be initiated manually or automatically.

Currently this feature is supported on the following devices:

•ONVIF compliant

•Axis with firmware 5.x or higher

•Sony SNC-CX600

•full Digital Watchdog camera line

•All Hanwha cameras.

If the device supports 2-way audio, the following button appears:

First, it is necessary to configure audio source: go to the General tab and choose First Source and Second Source. Audio will get mixed from both devices. The best practice is to select master from the sound card as primary and microphone as secondary. In this case, both sounds from Nx Witness (i.e. video clips) and microphone will be recorded simultaneously.

To manually say something on camera press the button and hold while speaking. It is necessary to have a microphone connected and set up. Use spectrum analyzer check the level while the button is pressed and hold:

When the button is released, the transmission is over.

It is possible to play sound or say a text on a device when an event occurs. See "Play Sound, Repeat Sound, and Speak" topics for more details.