An inner ear, dear, from The human body; an account of its structure and activities and the conditions of its healthy working, by the Martins: H. Newell and Ernest Gale. Their physiology guide can be found in the Biodiversity Heritage Library.
That chamber is where sounds get turned into nerve impulses.
H. Newell Martin was a young genius and distinguished physiologist – the first physiology professor at Johns Hopkins, and one of the first five full professors appointed to the faculty – who fell victim to “neurasthenia and alcoholism.”