My son has started saying a phrase repeatedly

The other day I heard my son say something, but I didn’t quite catch it. I thought he had asked me a question. I said, “what?” And he didn’t respond. I called his name to get his attention and asked again. He seemed surprised said “I didn’t say anything.” This has happened once or twice a day for the last week or so. Then friday we were talking on the phone and this same phrase popped out at the end of each sentence. His sentences make sense, but then there is just this tacked on phrase that sounds like “not hall” or “naught haul” or something like that. He doesn’t seem to know he says it when I question him about it. Yesterday he started saying it about every 15 seconds. This continued all day and by nighttime he was saying it rapidly Many times and then would be silent for half a minute and then do it again. At some point he went to sleep and it stopped. He has earbuds in his ears to listen to music almost constantly but still this word pops out kind of monotone and low. What is this and why has he just now started doing this?

Will you be going with him to the doctor? If so you should tell them about this. It might be a good idea to go to the doctor with him if you can arrange that.

Seems fine, just an extra bout of positive symptoms. If it’s nonviolent or threatening, what is the actual harm of him doing it?

You realize we suffer from brain damaging, yeah? Sometimes I would go through phases where I’d have to talk aloud to calm myself down, too much pent up energy or the brain simply running flat and hurting.

Seems like he has developed a private tactic to help cope with the voices, nothing more. I wouldn’t worry about it.

Yes, seems like a coping mechanism.

As others have mentioned - perhaps its a coping mechanism. Sometimes these pop up during stressful times for the person. Try to watch the ebb and flow of it and see if it might be tied to stress in his life (of course, a lot of stress is internal to our minds, so may not be visible).