Adding a wav file half way through the duration of a signal?

Hello,

   I have a signal y=filter(b,a,s) and I would like to add a wav file half way through y. Could anyone give me some tips please?

Thanks in advance.

Catarina

[Wayne King]

when you say "add a wav file" can you be more specific? Do you mean insert the wav file between the two segments of the signal, or literally add sample by sample to the existing signal. If the latter, what is the length of y and the length of the wav file?