An unsuited throat for singing

Unfortunately, if the incisura of the thyroid cartilage is really visible, then that individual’s throat may not be suited for singing.

When the incisura of thyroid cartilage is visible, the thyroid cartilage and cricoid cartilage lean forward, causing (Larynx Deep Position) LDP. Noticeable symptoms would be feeling a lump, choking and/or coughing in your throat which absolutely obstructs singing.
Even if you do not have LDP, (in regards to the cricoid cartilage) if the cricothyroid articulation cannot move wide enough, as shown in the drawing below, it is difficult to let out a high and low pitched voice.