How do I estimate if in recorded sound samples is present an echo caused from walls reflection ? 
(maybe there are multiples echoes: delayed, attenuated versions of the signal itself).

I'm recording several sound samples in my room and I suppose that in the recorded audio samples is present an echo image of the original sound. 
How do I verify if this is true and in case, how can I calculate the samples delay (ms echo reflection time from the walls) ?

I plot the cross-correlation of the samples with itself (xcorr in MATLAB, about 40000 samples, ~1 second) but I don't know which pattern to look for to check if one or more echoes are present. 

![xcorr](https://i.stack.imgur.com/aDA3v.png)

If I can understand the presence of the max peak in the middle of the graph, what are all the others equally spaced peaks on the both sides of the xcorr plot ? 
Eventually, how do I estimate the echo parameters from the recorderd samples (ms delay or samples delay) ?