I only received the hot air fryer today and have not yet put it into operation.
You can read the manufacturer's specifications and the test results about the volume on the web with corresponding comparisons to the Ninja 300 or 400 Dual Zone (videos on the web). There it is only pointed out that the warning signals for the shaking of the goods or the notification of the completed process can be very loud. It may be possible to change this volume or switch it off immediately. None are silent during operation. It is estimated to be between 50 and 60 decibels without warning signals. MFG.