Whichever part of the basilar membrane is vibrating sends that information to the brain, where the impulses are interpreted as sound of a particular frequency. Fovea is high concentration of cones for detail, optic nerve passes out at blind spot. The retina consists of several types of neurons and light-sensitive cells. You might guess that light striking a rod or cone would cause it to depolarize and send an impulse to the brain. Na comes into cell, depolarizes it.
Bipolar cell is inhibited from firing.
Vice-versa for the left eye. In most of the retina, many rods or cones connect one bipolar cell so a particular region of the brain receives visual input from several nearby rods or cones and vision is not high-definition. High acuity is possible in the fovea, where each cone makes a connection to one bipolar cell and each bipolar cell connects to one ganglion cell. Thus the light information from a very small part of the visual field is received by many brain cells and the object is magnified. Rods all are sensitive to the same wavelength of light, but cones come in three different sensitivities, blue, green, and red.