Vocal Type: Lyric Countertenor
Vocal Range:3.1 octaves A2-Bb5
Whistle Register: No
Vocal Pluses: An unusually high voice for a man, Colfer has an outstanding capability for production of notes in a way that is both light and powerful, giving him a very identifiable voice that can be sweet and lyric, as well as powerful and piercing.
The lower register (below D3) is hardly ever used, but is actually quite powerful for his voice type [Give Up the Funk]. Though it sounds as though the larynx may have been lowered slightly to enhance the sound, the technique used to reach his absolute lows is otherwise perfect.
The chest register, when unconnected to the head voice, can be powerful and capable, having an extremely punchy, belty sound [Rose's Turn]. Otherwise, when the sound is more often than not mixed with the head voice, the sound can either be light and sweet [Defying Gravity], or can have an extremely focused, edgy sound [Le Jazz Hot].
The head voice is the defining feature of Colfer's voice, and the clearest aspect of the individual sound he has. The lower head voice has a covered and cloudy sound that eventually gives way at around D5 to an immensely clear and piercing high head voice, up to Bb5.
Overall, all of the registers of his voice overlap consistently, so while the tone may not be identical from bottom to top, it is all produced in a healthy manner, and is extremely well-mixed with a head-dominant sound. The registers are easily connected, and can be demonstrated best in the final vocal slide from F#3 to F#5 in [Le Jazz Hot].
Vocal Negatives:The voice's sound can get a little too piercing at times. Also, sometimes, the mixing is done unevenly, with a head voice that is almost too flute-like to be used viably, belying problems with using a fuller, rounder support. This was more so a problem in earlier seasons of 'Glee', and has all but vanished starting mid-season 2.
Thanks to Ethan for putting this together