Until now, there were few supports on reading the mathematical expressions except text based expressions, so it is important to provide the reading of the mathematical expressions. Also, there are various of obstacles for people who are not visually impaired when reading the mathematical expressions such as the situation of presbyopia, reading the mathematical expressions in the vehicles, and so on. Therefore, supports for people to read mathematical expressions in various situations are needed. In the previous research, the main goal was to transform the mathematical expressions into Korean text based on Content MathML. In this paper, we expanded the range of the research from a reading disabilities to people who are not reading disabilities. We tested appropriacy of the rules we made to convert the MathML based expressions into speech and defined 3 math-to-speech rules in korean based on levels. We implemented the mathematical expressions by using 3 math-to-speech rules. We took comprehension test to find out whether our math to speech rules are well-defined or not.