"Are present feedback loops?"

I think the auditory system is basically centripetal.  Although physiological pathways from brain to ear have been described, I think they are a solution to a non-existent problem -- there are no clinical otologcal or audiological syndromes attributable to the brain (mis)directing the ear.

The hair cells in the inner ear transduce pressure waves into a neuro-chemical response that activates primary auditory nerve fibers. These fibers carry information from the inner ear and terminate in the brainstem auditory nuclei. There is a feedback loop from these nuclei back to the hair cells called the efferent system. 

Dear Alessandro,

It is a long question and the answer is much longer.There is an afferent system that carries the signals originating from the sensory hair cells to the brain via spiral ganglion neurons located in the cochlea. The efferents system originates from the brainstem auditory nuclei and innervates the hair cells, possibly involved in fine tuning of hearing function and also sound localization. Afferent pathways use excitatory neurotransmitters such as glutamate. Efferent pahways are inhibitory and using acetylcholine.

Here I have included couple of figures that I have used in my thesis, for details and references see my PhD thesis. I also recommend papers by Hudspeth, and also the Principles of Neural Sciences book by Kandel et al.

Best wishes, Refik

Thesis Molecular physiology of ATP-gated ion channels assembled fro...

"There is a feedback loop from these nuclei back to the hair cells called the efferent system."

Yes, but what clinical syndrome results from damage or absence of this efferent loop?

In a living organism that has an otherwise functioning brain stem so that there is a beating heart and breathing it is difficult to imagine damage or absence of the efferent loop in the presence of an afferent loop. So, my short answer would be that there is no clinical syndrome resulting from the absence of an efferent loop. 

With respect to your interest in feedforward versus feedback auditory networks, I suggest you look at the work of Ted Jones. His work primarily takes a chemical anatomical perspective. Here is a link to one of his reviews: Article Chemically Defined Parallel Pathways in the Monkey Auditory System

When we imagine our brain as the leader of the orchestra of our body . It should not only recieves signals from the cochlea it should slso communivate with the cochlea ; may be through olivocochlear bundle .