In this paper, we addressed the issue of choice of unit size in unit selection synthesis. We built the Hindi synthesizer for different choices of unit size: syllable, diphone, phone and half phone. We conducted perceptual tests to evaluate each of these synthesizers in comparison with other. From the perceptual results, it was observed that the syllable unit performs better than diphone, phone and half phone, and seems to be a better representation for languages such as Hindi. It was also observed that the half phone synthesizer performed better than diphone and phone synthesizers, though not as well as syllable.