The earliest hearing aid, by some accounts, dates to the 17th century, with French priest and mathematician Jean Leurechon’s documenting of an ear trumpet in his book Recreations Mathematique. Advances did not come until the late 19th and early 20th centuries, with Miller Rees Hutchinson's invention of the first portable hearing aid using a carbon transmitter, followed by engineer Earl Hanson patenting a vacuum tube version that quickly became a commercial success. And while the technology since then "has made strides in terms of speech," according to Emily Sandgren and Joshua Alexander of Purdue University, hearing aids remain “subpar” for music lovers.