Sounds like torn cartilage.. In fact I'd bet on it... And I'm not a betting woman.
Yes I have experienced the same. As we age the padding between muscles and bones can actually be worn away from an old injury or arthritis. The first time I heard mine I was home alone walking down the hall and turned around thinking someone was in the hall with me. In some cases this can be repaired. I have had heart surgery that was not totally effective so being put to sleep to correct mine is not worth the chance on being put to sleep. Tell your husband I feel his pain. Take Care