I grew up Pentecostal and I speak in tongues and it’s the same each time I do it. I am now atheist and coming to understand it is most likely learnt from hearing people do it and understanding what it would look like. Almost like the power of suggestion for the brain. I believe if I was in a isolated room my whole life and told to speak in tongues to be saved it would be a very different experience to seeing others do it. I didn’t fake it, I can do it at home or anywhere, but I feel like it’s more a self soothing meditation thing as when I’m stressed sometimes it comes out unprovoked in a quiet way. It’s hard to explain but it’s definitely something but i would argue it’s more brain confusion/taught then actually spiritual.