Plotting Experimental vs Theoretical Filter in Matlab

I have designed an IIR filter in matlab and then used those coefficients to do some audio filtering on some additional hardware. I then logged several frequencies using a function generator and an oscilloscope. Now I'd like to take the data I've collected and compare it to the original filter in matlab. Data pieces I have:

1. Original filter coefficients.

2. Input and output amplitudes of the experimental filter at a range of different frequencies.

If I plot the theoretical filter using code like this:

H = dsp.IIRFilter('Numerator',bcoefs,'Denominator',acoefs);

fvtool(H);

I get a nice curving theoretical graph.

However, my experimental data when I plot it like this:

plot(freqs,sfilter);

Where freqs is a vector of my frequencies and sfilter is a vector of the amplitudes I get a linear graph.

I need help figuring out how to compare my theoretical filter to my actual data. Any ideas here would be greatly appreciated.

Thanks in advance.