Rather than spending your money to build new wall, you can simply get a room divider and place it up in the space that you want to divide. There are many ideas of you may implement as hanging dividers are deemed convenient, easy to keep and more presentable. The good thing about room divider is you may use them in nearly every room. Or you can even just add room divider to a current wall in order to raise the sound proof properties.
You can use a staggered bookcase system as your room divider for a more airy feel. Or try to make a recycled wooden pallet room divider so you can easily hang things on it or perhaps draw the wooden pallet to make it look more artsy. Or try to string thick rope from the floor to ceiling as your creative room divider. see more 32 simple but useful room divider below to inspire you.