My daughter is 3.5 years old. She doesn't sound few letters like 'L' but 'N' instead. But I believe she will learn that by time.
However few weeks back I noticed that she speaks from her nose (nasal speech). The way she speaks words ending with 'N' or 'M' are different. Eg. she says Rumb
instead of Rum
.
Is there any practice or speech therapy we can bring in daily practice to improve her way of speaking?