Dear Sunny,
one of the beauties of modern keyboards, including arrangers, is the chance to reproduce quite accurately real instruments.
The main factor is the quality of the sample (of any instrument, as a piano, guitar, sax, ecc.). And that is an enormous and sophisticated work that has been carried by the manufacturer, in our case Yamaha. And from one model to another, within the same brand, the sample quality gets more accurate as you move from entry level arranger to higher level ones, with the best samples available in the flagship arranger (in our case, Genos).
But the realism of a sound (voice, in our case) does not depend only from the quality of the sample. Good brands in their best keyboards, provide precious "tools" to give the player the chance to issue a performance that is almost perfectly realistic.
This can be achieved thank to other tools (than just a good sample), like velocity control (the velocity you use to touch the key) and aftertouch (the further pressure that you put on the key in a second time).
If you listen to any song, you will notice that different notes are played with different volume (key velocity), and that in some of those notes the sound will change, adding nice nuances, depending on the instrument (as mikf mentioned).
The aftertouch effect varies from one voice to another, and my suggestion is that you make trials on some basic sound, like for example an acoustic guitar, a saxophone, a trombone, but also on some synth sounds.
Once you will have realized what a difference you get with aftertouch your playing will become more and more fascinated.
Ciao
Angelo
