How to increase the speed of this program?

[HYRY]

I want to join two mono wave file to a stereo wave file by only using
the default python module.
Here is my program, but it is much slower than the C version, so how
can I increase the speed?
I think the problem is at line #1, #2, #3.

import wave
import array
lfile = wave.open(lfilename)
rfile = wave.open(rfilename)
ofile = wave.open(ofilename, "w")
lformat = lfile.getparams()
rformat = rfile.getparams()
lframes = lfile.readframes(lformat[3])
rframes = rfile.readframes(rformat[3])
lfile.close()
rfile.close()
larray = array.array("h", lframes)
rarray = array.array("h", rframes)
oarray = array.array("h", [0]*(len(larray)+len(rarray))) #1
oarray[0::2] = larray                                    #2
oarray[1::2] = rarray                                    #3
ofile.setnchannels(2)
ofile.setsampwidth(2)
ofile.setframerate(lformat[2])
ofile.setnframes(len(larray))
ofile.writeframes(oarray.tostring())
ofile.close()