Your main program will then call a subroutine that fills in the audio data with sinusoid waves whose frequencies are those selected by the user . This subroutine will receive (as an argument) the pointer-to-pointer to short int audio-data array. (Note: you calloc( )'d a 2-D array in step 3). The name of this array is a pointer-to-pointer-to-short int. It holds the memory address of the start of the 0th cell of the 1-D array of pointers to the rows of the 2-D array. Therefore, your subroutine can access the pointers to the start of each row, and therefore access the values in each row. See previous programming assignments for more information. 7) Open a file called tones2.wav in the directory from which your program is executed. Open it in mode "wb". 8) Write out the wav file header using a single fwrite( ). 9) Finally, write out the audio data. In a stereo wav file, the data from the left and right channels are interleaved; first one 2-byte sample for the left channel, then one 2-byte for the right channel, then one 2-byte for the left channel, etc.. Use a for-loop to write out these interleaved 2-byte samples from the 2-D array. 10) fclose( ) the wav file. 11) free the allocated memory