That sounds like my daughter with whistling right now, she'll make the right mouth movement and then rather than actually whistling she'll just speak the whistle sound.One of the things I most enjoy about watching them develop is seeing the cogs turning in their brain while they figure stuff out.
I remember our eldest trying to figure out how to blow a raspberry when she was a baby. She could see it involved sticking your tongue out and a noise happening, but her interpretation was to do literally that and hum for the sound.
I was so proud when she finally figured it out, and she did it non stop all day!
Mine is doing this at the moment as wellThat sounds like my daughter with whistling right now, she'll make the right mouth movement and then rather than actually whistling she'll just speak the whistle sound.