What's the point in knowing your vocal range and voice type ? I'd also like some insight on tessitura and the purpose of knowing it. If the tessitura is the spot within your vocal where you sound the best and perform the most comfortably then the tessitura is more important to know than the vocal range right? Can I use this information to transpose music according to my voice type and tessitura? Does this apply solely to music or to speech as well? Any help will be greatly appreciated.
Tessitura is a term more accurately applied to the range of songs, as opposed to the vocalist's range. As in a song may have few or many notes that are slightly out of 'normal' range for a particular voice (tenor, for example), and this impacts on the ability to sing comfortably. Thus a song with a high tessitura would have a lot of high notes, none of which a vocalist would not be able to reach, but strain would be made due to singing at the edge of that person's range.
Range, obviously, is between the lowest and highest notes someone can comfortably reach. So, yes, knowing one's range is of paramount importance to a singer. This then can be translated to the highest and lowest notes in a particular song, and a comfortable key assigned.
That said, the actual sounds of some words can affect certain of the higher notes, so it's not an exact science. Also, some songs need to be sung close to the extemes of a vocalist's voice, for effects.
So, even if one says that one is a baritone, one may find that actually in some songs, the 'baritone key' is not the best. I question whether knowing one is a baritone is that important, compared with knowing one's range - which can stretch either side, or not.