She used a shifting tone to convey the changes that Mrs. Mallard have gone through. She weeps immediately "with sudden, wild abandonment" , she even used the phrase storm of grief, and suspension of thought to show how sad and shocked she was. She showed how her thought process is changing. Using phrases such as "her pulses beat fast" and her eyes become "clean and bright". Proving that she is free. She didn't stay depressed. That's how she has done it.