there are auditory "lenses," which place high-resolution sounds in precise locations in a three-dimensional environment. These can be built into eyeglasses, worn as body jewelry, or implanted in the ear canal.
Statement text from the data file published with the LessWrong 2020 assessment (https://www.dropbox.com/s/jmvciqv7u3rs7x5/Kurzweil_2019.tsv?dl=0), which splits the chapter into 105 statements. The source list repeats the preceding sentence as bracketed context; the context is not repeated here.