Power of a speech signal I have been asked to calculate the power of a speech signal given by the following:
$$\ p(x)= \left(\frac a2\right)e^{-a\mid x \mid}$$ 

I know the formula for the power of a signal to be the following:

$$\frac{1}{T}\int_\frac{-T}{2}^\frac{T}{2}p(x)^2dx$$

Only this is not a periodic signal so I don't know where to set the upper and lower limits. I have tried taking the Fourier transform and evaluating but that gives me $\ P(f) = \frac{a^2}{a^2+2\pi f^2} $. If anyone would be able to guide me through a solution to this I'd really appreciate it. Simon.
for negative 'a' you can limit the integration up-to the 5-6 times of time constant of the dying exponential(as per your equation). this will give you the power approximately equal to actual.
The time constant of dying exponential is given by 1/abs(a). more details could be checked at https://en.wikipedia.org/wiki/Exponential_decay