Addendum: Thinking about it I do not understand what you expect to hear. There is no oscillation in the sinh function. There is no audible content. Are you looking to somehow modulate some audible signal with a sinh variation?
int endFreq = 5000; //final frequency in Hz adjust it to suitint timebase = 5000; //sets the rate of change adjust it to suitint freq = endFreq * (1 - exp(-(float)millis()/timebase));
I want pitch modulation, change the value of a tone across a 1 second period of time. I change the output steps of a pitch to climb in a sloped arc (like the camera flash sound)
I would suggest that you use an exponential function to modify the frequency, after all that is what is really happening when a flash charges.