To enable voice chat in Roblox you should follow these steps:
Full Answer
To disable the Spatial Voice feature, follow the instructions below:
You need to be verified as age 13 or above to turn on and use voice chat in Roblox. Provided you meet the above condition, simply follow the below steps to enable the Spatial feature: It will turn from grey to green, indicating that voice chat has been enabled for your account.
As nearly half of Roblox's player base consists of users over the age of 13, how to properly manage the safety of younger users has remained a concern. In a blog post, Roblox stated that the spatial voice feature will only be accessible to those who have verified that they are over the age of 13.
Once you've verified your age, voice chat can be toggled on and off within the setting menu. On PC, look for the gear icon in the upper right hand corner, then from the drop down menu click Settings. From settings, locate the Privacy tab from the menu on the left.
As of now, there's been no official statement regarding what can and can't be said over voice chat. Currently, swearing receives no form of punishment or censoring by Roblox—this will more than likely change however as the kinks continue to be worked out.
Whether you view it as unfortunate or not, not every Roblox experience will feature voice chat compatibility. The decision is completely up the individual game developers as to whether or not they want to allow it. If you're looking for a game to try out voice chat, Mic Up appears to be the current favorite.