Normalise data which has peaks
You could normalize the average amplitude, i.e.

YData = YData / mean(abs(YData));


Or you could normalize the signal power to one, i.e.

YData = YData / sqrt(mean(abs(YData).^2));


If just the peaks are bothering you, you could use dynamic range compression, but that would introduce nonlinear distortions. As Phonon hinted, please tell us why you are not happy with the results and why you want to normalize your data in the first place. That would allow for a more precise answer.