On the 28th of December, Park Hyewon debuted as soloist HYNN with 'Let Me Out'. 'Let Me Out' is a British pop song based on the acoustic guitar, describing the feeling of resentment and pain after a break-up in which she was the on who loved more.

HYNN is most known for her participation on the eigth season of Superstar K, in which she finished in third place and gained the nickname 'vocal diva' due to her outstanding vocal capabilities.