Bass (sound) in the context of "Treble (sound)"

Accordions (from 19th-century German Akkordeon, from Akkord—"musical chord, concord of sounds") are a family of box-shaped musical instruments of the bellows-driven free reed aerophone type (producing sound as air flows past a reed in a frame). The essential characteristic of the accordion is to combine in one instrument a melody section, also called the diskant, usually on the right-hand keyboard, with an accompaniment or Basso continuo functionality on the left-hand. The musician normally plays the melody on buttons or keys on the right-hand side (referred to as the keyboard or sometimes the manual), and the accompaniment on bass or pre-set chord buttons on the left-hand side. A person who plays the accordion is called an accordionist.

The accordion belongs to the free-reed aerophone family. Other instruments in this family include the concertina, harmonica, and bandoneon. The concertina and bandoneon do not have the melody–accompaniment duality. The harmoneon is also related and, while having the descant vs. melody dualism, tries to make it less pronounced. The harmonium and American reed organ are in the same family, but are typically larger than an accordion and sit on a surface or the floor.

Equalization, or simply EQ, in sound recording and reproduction is the process of adjusting the volume of different frequency bands within an audio signal. The circuit or equipment used to achieve this is called an equalizer.

Most hi-fi equipment uses relatively simple filters to make bass and treble adjustments. Graphic and parametric equalizers have much more flexibility in tailoring the frequency content of an audio signal. Broadcast and recording studios use sophisticated equalizers capable of much more detailed adjustments, such as eliminating unwanted sounds or making certain instruments or voices more prominent. Because of this ability, they can be aptly described as "frequency-specific volume knobs."

A subwoofer (or sub) is a loudspeaker designed to reproduce low-pitched audio frequencies, known as bass and sub-bass, that are lower in frequency than those which can be (optimally) generated by a woofer. The typical frequency range that is covered by a subwoofer is about 20–200 Hz for consumer products, below 100 Hz for professional live sound, and below 80 Hz in THX-certified systems. Thus, one or more subwoofers are important for high-quality sound reproduction as they are responsible for the lowest two to three octaves of the ten octaves that are audible. This very low-frequency (VLF) range reproduces the natural fundamental tones of the bass drum, electric bass, double bass, grand piano, contrabassoon, tuba, in addition to thunder, gunshots, explosions, etc.

Subwoofers are never used alone, as they are intended to substitute the VLF sounds of "main" loudspeakers that cover the higher frequency bands. VLF and higher-frequency signals are sent separately to the subwoofer(s) and the mains by a "crossover" network, typically using active electronics, including digital signal processing (DSP). Additionally, subwoofers are fed their own low-frequency effects (LFE) signals that are reproduced at 10 dB higher than standard peak level.

House dance is a freestyle street dance and social dance that has roots in the underground house music scene of Chicago and New York. It is typically danced to loud and bass-heavy electronic dance music provided by DJs in nightclubs or at raves.

Eurodance (sometimes referred to as Euro-NRG) is a genre of electronic dance music that originated in the late 1980s in Europe. It combines many elements of rap, techno and Eurodisco. This genre of music is heavily influenced by the use of rich vocals, sometimes with rapped verses. This, combined with cutting-edge synthesizers, strong bass rhythm and melodic hooks, establishes the core foundation of Eurodance music.

Bass violin is the modern term for various 16th- and 17th-century bass instruments of the violin (i.e. viola da braccio) family. They were the direct ancestor of the modern cello. Bass violins were usually somewhat larger than the modern cello, but tuned to the same nominal pitches or sometimes one step lower. Contemporaneous names for these instruments include "basso de viola da braccio," "basso da braccio," or the generic term "violone," which simply meant "large fiddle." The instrument differed from the violone of the viol, or "viola da gamba" family in that like the other violins it had at first three, and later usually four strings, as opposed to five, six, or seven strings, it was tuned in fifths, and it had no frets. With its F-holes and stylized C-bouts it also more closely resembled the viola da braccio.

The name "bass violin" is also sometimes used for the double bass.

Bassline (sometimes referred to as bassline house or 4x4 or niche) is a music genre closely related to speed garage that originated in South Yorkshire and the West Midlands in the early 2000s. Stylistically it comprises a four-to-the-floor rhythm normally at around 135–142 beats per minute and a strong emphasis on bass, similar to that of its precursor speed garage, with chopped up vocal samples and a pop music aesthetic. The genre is often confused with grime music; however, it deviates from grime's aggressive electronic sound and rapid syncopated breakbeats, instead having a more mainstream-friendly sound.

Particularly in the scene's early days, the most prominent bassline club was Sheffield's Niche Nightclub, which became the centre of controversy due to a police raid which resulted in the club's closure in 2005.

Dubstep is a genre of electronic dance music that originated in South London in the early 2000s. The style, whose roots trace to the Jamaican sound system party scene in the early 1980s, emerged as a UK garage offshoot that blended 2-step rhythms and sparse dub production, as well as incorporating elements of broken beat, grime, and drum and bass.

Dubstep is generally characterised by syncopated rhythmic patterns, prominent basslines, and a dark tone. In 2001, this underground sound and other strains of garage music began to be promoted at the London nightclub Plastic People, at the "Forward" night (sometimes stylised as FWD>>), and on the pirate radio station Rinse FM. The term "dubstep" appeared around 2002, used by labels such as Big Apple and Tempa to describe remixes more distinct from 2-step and grime.

In music theory, the bass note of a chord or sonority is the lowest note played or notated. If there are multiple voices it is the note played or notated in the lowest voice (the note furthest in the bass.)

A woofer or bass speaker is a technical term for a loudspeaker driver designed to produce low frequency sounds, typically from 50 up to 200 Hz. The name is from the onomatopoeic English word for a dog's deep bark, "woof" (in contrast to a tweeter, the name used for loudspeakers designed to reproduce high-frequency sounds, deriving from the shrill calls of birds, "tweets"). The most common design for a woofer is the electrodynamic driver, which typically uses a stiff paper cone, driven by a voice coil surrounded by a magnetic field.

The voice coil is attached by adhesives to the back of the loudspeaker cone. The voice coil and the magnet form a linear electric motor. When current flows through the voice coil, the coil moves in relation to the frame according to Fleming's left hand rule for motors, causing the coil to push or pull on the driver cone in a piston-like way. The resulting motion of the cone creates sound waves, as it moves in and out.

In music theory, a ninth chord is a chord that encompasses the interval of a ninth when arranged in close position with the root in the bass.

Heinrich Schenker and also Nikolai Rimsky-Korsakov allowed the substitution of the dominant seventh, leading-tone, and leading tone half-diminished seventh chords, but rejected the concept of a ninth chord on the basis that only that on the fifth scale degree (V) was admitted and that inversion was not allowed of the ninth chord.