This paper presents four experimental methods for the evaluation of growth rates of combustion insta- bilities. A systematic investigation is conducted on a laminar slot burner with five operating points (two stable and three unstable). The accuracy of the methods is assessed by cross comparison and the use of three different flow variables as input: velocity, pressure and heat release rate fluctuations. Finally, the experimental determinations of the growth rates are compared to the prediction of a low-order acoustic model fed with a Flame Transfer Function.