Chnage voice of file as quick as posibly

FMOD Engine
1

I want to change voice of file as quick as posibly. I used follow code:

result = system->playSound(sound, 0, 0, &channel);
ERRCHECK(result);
//Spped 10 times
float frequency;
channel->getFrequency(&frequency);
frequency = frequency * 60;
channel->setFrequency(frequency);

But it seems doesn’t work. Could you give me some advice? I really need it to develop a tool for file voice changing.

Thanks.