I often focus on sounds in my meditation practice, simply because it’s the one object (besides the breath) that I can direct my awareness towards for any decent amount of time.
Of course, this is a practice that’s much sexier in nature (i.e., sounds of waves crashing, gulls screaming, leaves rustling, and so on and so forth). In the privacy of my home, or the studio, very often what I hear are:
And, yes, the refrigerator humming.
Well, we’ve got to work with what we have.