I would encourage merging the two for a while, as this may help overcome the primary hindrance you seam to be meeting, and they do support eachother, but it is up to you. if you click on the sutta name above it links to my translation, so you at least know what you are looking for.
try having a look for Ajahn Sumedho talks on the sound of silence (there is at least one free book by that name and one for money book also by that name if I remember,) I do have experience with it, however I would not be comfortable relaying this openly as it is not and has not been a main practice of mine at any point other than something which commes up from time to time, and I use when it is there at times... although any help in resourses I can provide feel free to PM me directly or hope I see this thread and remember
I have had a look at texts on this phenomenon though, and Ajahn Amaro calls it the numa sound (SP? I did have dragosta din tai run through my head when he said it on occasion
) and a very good book on this is called the art of attention by salim something-or-other, sorry I can not remember the full name, but will edit this post later with a link to the book (it was Ajahn Amaro who talked the publisher into doing a new edition, i believe)
this sound is found with in a mahayana text the suranayagama sutra (sp?) so although buddhism does have references to it, it certainly isn't developed to any degree I know of within buddhism as a whole or more specifically within theravada, although as mentioned Ajahn Sumedho does teach it and developed it outside of any knowledge of other systems using it. the text talks briefly, one or two lines at most, of Avalokitesvara hearing the sound of all living beings screams in the world, and feel compassion, or something to this effect. when I read that it occured to me, as I was hearing it more than often at that point, that this sound could be seen as our internal world (six sense spheres) scream for compassion, and the phenomenon isn't limited to sound, it can also be seen, felt, tasted... there is always a background neutral element to the senses we just don't notice.
Hinduism does have more of a developed system within their texts but it is a case of if it works and does what you are looking for (i.e. a useful tool to use on the path) use it, if not there are other methods.
if you would like any more or have any more questions I will try to answer, I can relay some instruction I have recieved in the past if you wish.