Addon aircraft sound

[pc8775]

I have noticed that 2 of my addon aircraft do not have sound when I switch to the spot view.  Is there a way to edit the sound.cfg for those aircraft so I can hear sound when in the spot view mode?  
  Just a note to add :  Both of these aircraft did not come with sound sets and I have added in custom sound files that I have found in the file library.
                                       Thanks,
                                       Paul