I was just listening to the song “tera woh pyaar” by Momina Mustehsaan and Asim Azhar. In the intro lines, at 0:58 to 1:01 (youtube version), you can notice Momina sings “teri tarah hmmm khushboo chalein”. Notice the “hmmm”. According to me, this is a way to recalibrate and stay within the limits of the song’s scale. It is comparable to you taking support to reach another place while climbing. These are usually the well note notes of the scale and they help you stay on the scale.
Of course, you might have noticed how singers set the “tone” for a song in the beginning by doing some hummings or aaalaaps.
