Another popular option id creating a vocal isolation booth.  This too can work if you don't want to treat the entire room.  Things to keep in mind when creating an isolation booth is size.  

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A smaller booth will sound "boxy" and somewhat unnatural.  Ideally you want at least a few feet around you but sometimes we work with what we have.

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For a booth to really sound natural you want a mixture of thick acoustic panels that absorb low frequencies.  It's tough to get it perfect but a booth is better than an open room without treatment.