talk to oneself
ペリーは独り言を言う癖がついた。
Perry had developed a habit of talking to himself.
祖父はひとりでいると、ときどき独り言を言う。
When my grandfather is alone, he sometimes talks to himself.
独り言を言うなよ。
Don't talk to yourself.
トムってよく独り言を言うんだよ。
Tom often talks to himself.