I do not want to categorise myself into an alto or mezzo or soprano, but do want to understand my comfortable voice range. I can do a siren exercise which ranges from b3 to b5 or c6 with ease.But while singing I am unable to sing as high as F5 or G5 with ease.Does this help in categorising my voice ? Or am I using wrong head voice accessing techniques?
How people are categorized into type is a somewhat debatable matter. One group believes that range is the first factor (this is more of a classical music approach), and the other (myself included) believe vocal quality is the first since ranges can be improved with practice. This is similar to someone improving their flexibility to be able to do a split. For me, Annie Lennox (she's hit an E6 by the way) is a perfect example of a contralto with an androgynous type voice. As far as your trouble with F5 and G5 if you can hit the siren you can hit those notes. Vocalizations of any type can be translated into singing, it just takes practice, exercise and relaxation. I find that making a yawning sound is very similar to a proper head voice. So, try vocally "yawning" those notes. Make sure that you become very relaxed in your throat area. Tensing your throat will contribute to your inability to hit those notes properly or at all. Take it slowly!! Also, unless you are going to be a part of a vocal group (such as a choir) then your type doesn't really matter, in that case the director will place you in the position he/she fits and this is based on your range.