Who is making that noise?

Lorena is clicking her tongue frequently. Her teacher says she does it as a happy sound, when she is working on something else. For us, she mostly does it in the car. Oh, and she does it very loudly. Pablo and I don't like it, we can live with it though, but it gets on Ax's nerves, especially as it interferes with her car reading.
Yesterday, we were driving home and Ax was reading (I know, what a surprise!), Lo covered her mouth with one finger and began the clicking. She would stop and say, "Arantxa, stop making that noise, Arantxa, why are you making that noise with your tongue?" Pablo told her that we knew it was her, "no, it is not, it is Arantxa."

It was similar to last week. We went to one of those new water park/hotels (awesome!!), and we had to separate the girls into 2 beds since Lorena was not letting her sister sleep. The room was pitch dark, and we start hearing this big noise from Lo's side (thumping the mattress with her leg). "Who is making that noise? I can't sleep with that noise! Can you please stop that noise?" We told her to stop kicking the mattress. She then starts moving in the bed saying "what is that swishing sound? I can't sleep with that swishing sound?" I must admit she was right, the sheets were noisy ;).