if adiponectin and leptin are both secreted by fat cells, then why would leptin levels increase but adiponectin levels decrease? It would seem only logical that both would increase as you accumulated more fat.
Your “ear” analogy for leptin and insulin is a good one. Given a high circulating level of either hormone eventually de-sensitizes the respective cell receptors, it could be characterized as “losing a sensitive signal among too much noise” or similar. These mechanisms of action are fairly well established.
By contrast, adiponectin research is an emerging (and exciting) area of investigation. The exact reason why less of this hormone is released in overweight people has yet to be determined. It may be that, in the overweight state, an increased level of one or more other bioactive compounds inhibits the production of adiponectin in fat cells, but more research is needed to confirm what compounds, if any, do this.
What we do know is maintaining a normal blood level of adiponectin is associated with better metabolic and vascular health, specifically improved insulin function, increased fat burning [fatty acid oxidation], decreased fat content of muscle, reduced inflammation and improved blood vessel health. And, losing excess weight is one of the most effective ways to help maintain a healthy blood adiponectin level in the normal range.