In the 1930s, musician and inventor Paul Tutmarc of Seattle, Washington, developed the first electric string bass in its modern form, a fretted instrument designed to be played horizontally. The 1935 sales catalog for Tutmarc's electronic musical instrument company, Audiovox, featured his "Model 736 Bass Fiddle", a four-stringed, solid-bodied, fretted electric bass instrument with a 30 1⁄2-inch (775-millimetre) scale length. The adoption of a guitar's body shape made the instrument easier to hold and transport than any of the existing stringed bass instruments. The addition of frets enabled bassists to play in tune more easily than on fretless acoustic or electric upright basses. Around 100 of these instruments were made during this period.
In 1918 Baby Dodds (Warren "Baby" Dodds, circa 1898–1959), playing on riverboats with Louis Armstrong on the Mississippi, was modifying the military marching set-up and experimenting with playing the drum rims instead of woodblocks, hitting cymbals with sticks (1919), which was not yet common, and adding a side cymbal above the bass drum, what became known as the ride cymbal. Drum maker William Ludwig developed the "sock" or early low-mounted high-hat after observing Dodd's drumming. Ludwig noticed that Dodd tapped his left foot all the time. Dodds had Ludwig raise the newly produced low hats 9 inches higher to make it easier to play, thus creating the modern hi-hat cymbal. Dodds was one of the first drummers to also play the broken-triplet beat that became the standard pulse and roll of modern ride cymbal playing. Dodds also popularized the use of Chinese cymbals.
In traditional music such as country music, folk rock, and related styles, the bass often plays the roots and fifth (typically the fifth below the root) of each chord in alternation. In these styles, bassists often use scalar "walkups" or "walkdowns" when there is a chord change. In Chicago blues, the electric bass often performs a walking bassline made up of scales and arpeggios. In blues rock bands, the bassist often plays blues scale-based riffs and chugging boogie-style lines. In metal, the bass guitar may perform complex riffs along with the rhythm guitarist or play a low, rumbling pedal point to anchor the group's sound.