To elaborate on OP's comment, hearing (or any sense) is composed of two parts: Sensation and Perception. You can almost think of these things as hardware and software.

Sensation is the physical act of sensing stimuli. Hair cells in your cochlea receive vibrations which were carried through your ear drum and middle ear, and thus depolarize and send raw data to your brain. Same thing goes for the eyes. Rods and cones get hit by light and thus depolarize and send raw data to your primary and secondary visual cortices, where it's processed and your brain makes sense of what it's sensing. This processing stage is called Perception.

Now as a side note, a brains "processing power" is not based on it's sheer size, but it's surface area to size ratio. So this really becomes a matter of real estate. As the visual areas of your brain lose stimulation, they atrophy and your other areas now have more room to develop and repurpose to strengthen the processing power of the remaining senses. This is the general idea behind the concept of neural plasticity. This added processing power can take that same stimuli and, for example, better differentiate similar tones or provide better echolocation. An important point is that you can simply train this into yourself without necessarily losing a sense, it's just obviously more exaggerated in those that do.

Source: Bachelor's in Neurophysiology, but it's been a few years, so pardon some discrepancies.

Additional reading: Blind guy who's known for his ability to use echolocation does MRI, finds out that when he echolocates, it actually activates his visual cortex.

https://abcnews.go.com/Health/MindMoodNews/blind-man-echolocation/story?id=13684073