There is a common notion that many vocalists, who have been trained in classical singing, are not able to deliver a pop song that is worth listening to.
Former performer and voice coach, Roger Burnley, is among many who have made mention of this fact. He has admitted in several of his YouTube videos that he experienced the problem, when he tried to venture into pop music, after getting classical training in his younger years.
But why that is the case is a topic that has sparked debate on numerous online forums and blogs. The most common answers given by contributors on platforms, such as Quora, are those relating to technique and the differences in singing pop and opera. Generally, it is accepted that classical singing is way more technical and takes years to be perfected, if ever. Classical singing focuses on producing a full sound, properly rounded vowels, an open throat, and good posture. Also, delivering a song in classical form demands that all notes be held right through to their end.
On the other hand, it takes less vocal gymnastics to perform a pop song, for even the most accomplished singer. In fact, the allure of pop music is its closeness to conversation, i.e. its lyrical content, and the ability of the singer to improvise and make the melody more interesting. With opera and other classical styles, the performer is trained to follow a piece of music for a long period of time (hours) without hurting the voice.
For that reason, the action of singing classically becomes hard-wired into the psyche of many singers trained in this genre. It becomes near-impossible to abandon the preciseness of voice projection in classical music to accommodate shortened and (in some cases) nasal notes often found in pop singing, which are often amplified by a microphone.
Still, there have been quite a few singers with classical training, who were able to transition to pop music seamlessly. Both Celine Dion and Lady Gaga are said to have received classical training in their younger years, and they both sound awesome doing pop.