sound engineering honours,2 years diploma or 1 year diploma?

It depends on the laws of your local jurisdiction. In Alaska, where I live, the title engineer requires you to be a state licensed professional engineer. There are individuals, some of whom with nothing more than a high school diploma, who are referred to as an an "engineer" by the company or organization they work for. In the state of Alaska, you once could be a professional engineer, without formal engineering education, but with a minimum of 15 years work experience and successfully passing the professional engineering exam. Now, a professional engineering candidate is required to have a four year degree at an accredited engineering school and four years minimum work experience as an engineer in training. But it all depends on your local administrative laws.

It was not a engineer degree ! It is just a technician diploma and you are not qualified to approve or sign any design ! You need to go through the university 4 years training again before call yourself an engineer.