In the early 1940s, many jazz musicians, especially African American jazz musicians, started to stray from the popular big band dance music of the 1930s. Their experimentation and quest for deeper expression and freedom on the instrument led to the birth of a new style of music based from Harlem called bebop music. Whereas swing was a popular music designed for dancing, bebop was a "musician's music" designed for listening. During the bebop era, given that bands no longer had to accompany dancers, bandleaders could speed up the tempo. Bebop was also much more based on improvisation, in comparison to the heavily arranged big band scores. Bebop musicians would take an old standard and re-write the melody, add more complex chord changes, resulting in a new composition.
Drum bags are made from robust cloth such as cordura or from cloth-backed vinyl. They give minimal protection from bumps and impacts, but they do protect drums and cymbals from precipitation. They are adequate for drums transported in private vehicles to go to local gigs and sessions. They are often the only option for young drummers who are just starting out.
In some styles of music, drummers use electronic effects on drums, such as individual noise gates that mute the attached microphone when the signal is below a threshold volume. This allows the sound engineer to use a higher overall volume for the drum kit by reducing the number of "active" mics which could produce unwanted feedback at any one time. When a drum kit is entirely miked and amplified through the sound reinforcement system, the drummer or the sound engineer can add other electronic effects to the drum sound, such as reverb or digital delay.
The drum is a member of the percussion group of musical instruments. In the Hornbostel-Sachs classification system, it is a membranophone. Drums consist of at least one membrane, called a drumhead or drum skin, that is stretched over a shell and struck, either directly with the player's hands, or with a percussion mallet, to produce sound. There is usually a resonance head on the underside of the drum, typically tuned to a slightly lower pitch than the top drumhead. Other techniques have been used to cause drums to make sound, such as the thumb roll. Drums are the world's oldest and most ubiquitous musical instruments, and the basic design has remained virtually unchanged for thousands of years.
Drummers' usage of electronic drum equipment can range from adding a single electronic pad to an acoustic kit (e.g., to have access to an instrument that might otherwise be impractical, such as a large gong), to using a mix of acoustic drums/cymbals and electronic pads, to using an acoustic kit in which the drums and cymbals have triggers, which can be used to sound electronic drums and other sounds, to having an exclusively electronic kit, which is often set up with the rubber or mesh drum pads and rubber "cymbals" in the usual drum kit locations. A fully electronic kit weighs much less and takes up less space to transport than an acoustic kit and it can be set up more quickly. One of the disadvantages of a fully electronic kit is that it may not have the same "feel" as an acoustic kit, and the drum sounds, even if they are high-quality samples, may not sound the same as acoustic drums.
On early recording media (until 1925) such as wax cylinders and discs carved with an engraving needle, sound balancing meant that musicians had to be literally moved in the room. Drums were often put far from the horn (part of the mechanical transducer) to reduce sound distortion. Since this affected the rendition of cymbals at playback, sound engineers of the time remedied the situation by asking drummers to play the content of the cymbals onto woodblocks, temple blocks, and cowbells for their loudness and short decay.
Specific bass brands/models became identified with particular styles of music, such as the Rickenbacker 4001 series, which became identified with progressive rock bassists like Chris Squire of Yes, and Geddy Lee of Rush, while the StingRay was used by funk/disco players such Louis Johnson of the funk band The Brothers Johnson and Bernard Edwards of Chic. The 4001 stereo bass was introduced in the late 1960s; it can be heard on the Beatles' "I Am The Walrus." 
Drums are used not only for their musical qualities, but also as a means of communication over great distances. The talking drums of Africa are used to imitate the tone patterns of spoken language. Throughout Sri Lankan history drums have been used for communication between the state and the community, and Sri Lankan drums have a history stretching back over 2500 years.