I drive my boyfriend crazy with the repetition. I think it's echolalia.
I listen to the same tracks over and over to the point that he complains about it. "I know every sound of every song you play, intimately." Sometimes I'll find a section of a song that really appeals to me and I will "rewind" just that part of the song over and over again, hundreds of times. I do the same with movies or favorite TV shows..... I've watched Firefly and Serenity at least a thousand times, The Star Wars series double that. I'm just starting to Fringe again.
I've got crap repeating in my head all the time, usually "wawawawawa wa wa wawawa" or Lalalalalala" or "bumbumbumbumbumbum" Out loud, under my breath, while breathing in, in whistles, while drumming on things. Sometimes its parts of a favorite song or phrase. Or beats to a rhythm.
My favorite is the Imperial Death March. lol
I'll mimic unique sounds, like the cat meowing, the dog growling, birds whistling, chimes, train horns, etc... so annoying and I get embarrassed by it.
I'll repeat the last few words people say, but I'll do it in a foriegn accent. Sometimes over and over again.
"In social situations such as these it is generally customary to offer you a hot beverage, would you like a hot beverage" but in a blindingly Brittish accent, or Native. or Mandarin..... Sometimes it's just "Would you like a hot beverage?!?!?!" REALLY LOUD, long drawn out brittish lady accent.... That one makes the boyfriend laugh... All I'm really trying to do is offer the guy a drink.. I don't think he understands that it's involuntary...
I should also mention, he hates the music I listen to, it's repetetive beats and sounds.... Loops.
I know part of it is probably echolalia, but the rest of it I think might be simply stimming. My computer station I loving call the Strobing Star Ship Entropy is essentially a stimming station... Big huge speakers, lots of bass, mutliple monitors, I get the tunes cranked and turn on Milkdrop (fractal visualization program packaged with Winamp), wrap up my big double thick heavy fleece blanket, and just get absolutely lost.