Final answer:
A 14-year-old boy claiming an extensive vocal range from E1 to A7 is rare and he should consult with a vocal coach to ensure healthful use of his voice. Focus should be maintained on the range where the voice is most comfortable and resonant.
Step-by-step explanation:
The vocal range you have described is quite extensive for a 14-year-old and covers a vast spectrum from E1 to A7, incorporating various vocal techniques such as growling for the lowest notes, using subharmonics for the lower bass notes, your natural chest and head voice for the middle range, falsetto for the higher pitches, and whistle register for the very top of your range. It is indeed a rare occurrence to have such a wide vocal range, and it may be worth consulting with a vocal coach to ensure you are using these techniques properly and healthily to avoid strain on your voice. Additionally, while an extensive vocal range like this is possible, it is always recommended to focus on the range where your voice is most comfortable and resonant for consistent vocal development.