You start doing weird stuff, weird things will happen. I’m not being flippant there at all, it’s just a fact, and why lots of people get into this stuff then hurry back out when stuff starts happening.
Ask Belial for the real story, and we all have like a language-generator in our heads, the same way we can “see stars” just from rubbing our eyes etc., so maybe something triggered that, but this is why it’s good to have a method of divination and at least one solid entity to rely on as early as possible, to get answers to new phenomena like this.
PS can you record them? That might be interesting, leave a digital recorder running, or something. Or if you have a phone, call your own number, it should go to answerphone/voicemail so it’s just picking up and recording noise.