What genre of music  did Loudest Whisper debut on a vinyl record format characterized by a speed of 33 ⁄ rpm, a 12 or 10 inch (30 or 25 cm) diameter, and use of the "microgroove" groove specification?
LP record The LP (from "long playing" or "long play") is an analog sound storage medium, a vinyl record format characterized by a speed of 33 ⁄ rpm, a 12 or 10 inch (30 or 25 cm) diameter, and use of the "microgroove" groove specification. Introduced by Columbia in 1948, it was soon adopted as a new standard by the entire record industry. Apart from a few relatively minor refinements and the important later addition of stereophonic sound, it has remained the standard format for vinyl albums.
PocketDisc Pocket Disc was a type of flexidisc, made by Americom Corporation and experimented with in the late 1960s by 28 major record labels, (but some major labels such as Columbia Records, RCA Records, Motown Records, and MCA Records chose not to participate) and included popular artists of the era such as The Beatles, Aretha Franklin, The Beach Boys, Steppenwolf and Jimi Hendrix, that were small enough (four inches in diameter) to be carried in one's pocket or shipped in an envelope and not be as fragile as a standard record, but could still be played on the standard manual-only phonograph or record player (at 45 RPM).