There are lot of people who are not good at vocalizing the letter “N” sound.
The voice cannot be generated without air. This air comes out from the mouth more than the nose when singing.
When vocalizing the letter N, you close your mouth and the air comes out only from the nose, decreasing in the amount of air.
Therefore, you can not let out your voice loudly when vocalizing the letter N.
However, if you could put muscle into that action and extend your nostrils to increase the amount of air that comes out from the nose, you can vocalize “N” sounds loudly.
If you train in increasing the air that comes out of the nose over and over again, you can vocalize “N” sounds smoothly and unintentionally.
Note1:Humming is an action that also utilizes air coming out only from the nose to spread the voice and make sound. Applying the same method as mentioned above.
Note2:When breathing through the nose, usually only one side of the nasal cavity is used, alternately, not both sides at the same time.
Therefore, it’s no wonder that you have to increase the amount of air from the nose when vocalizing the letter “N”- because that letter’s sound is always at a lower volume than other letters.