Other forms: reedily; reedier
Use the adjective reedy to describe someone who's tall and thin, or a sound that's high-pitched. The reedy singer in your middle school choir might have a reedy voice.
Reedy people are lanky and tall, with long, slender legs that resemble reeds, the broad-leafed grasses that grow in marshy areas. Reedy sounds, on the other hand, seem to be made from a reed (or woodwind) instrument, like a clarinet. So your reedy singing voice is high and thin, rather than bold and deep like your father's baritone.