Not a problem, it may be that the sensitivity of the microphone in the Nursery Unit needs adjusting.
See the following for how to do so:
• Press the MENU/SELECT button on your Parent Unit to access the MAIN MENU on screen
• Using the arrows select the SETTINGS icon on screen to access the SUB-MENU
• Now select the VOX SENSITIVITY icon
• Press the UP/DOWN arrows to adjust as required - levels 1 (low) - 4 (high)
• Press the MENU/SELECT button to confirm/save your setting
Please note: if you do not press the MENU/SELECT button your monitor will automatically revert to the previous sound setting and you will need to begin again