Sub-bass is a term used to describe audible sounds below 90 Hz

Hertz

The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....

 and extending downward to include the lowest frequency humans can hear, typically 20 Hz. Sound systems often feature one or more subwoofer

Subwoofer

A subwoofer is a woofer, or a complete loudspeaker, which is dedicated to the reproduction of low-pitched audio frequencies known as the "bass". The typical frequency range for a subwoofer is about 20–200 Hz for consumer products, below 100 Hz for professional live sound, and below...

 loudspeakers that are dedicated solely to amplifying sounds in the sub-bass range. Sound below sub-bass is called infrasound

Infrasound

Infrasound is sound that is lower in frequency than 20 Hz or cycles per second, the "normal" limit of human hearing. Hearing becomes gradually less sensitive as frequency decreases, so for humans to perceive infrasound, the sound pressure must be sufficiently high...

.

Sub-bass can also refer to a bass guitar

Bass guitar

The bass guitar is a stringed instrument played primarily with the fingers or thumb , or by using a pick....

 that has greater than normal low frequency capabilities, such as heavier strings with lower tuning.

Hearing and usage

20 Hz is considered the normal low frequency limit of human hearing. When pure sine waves are reproduced under ideal conditions and at very high volume, a human listener will be able to identify tones as low as 12 Hz.

Audio tracks known as bass test

Bass test

A bass test is an audio recording, usually composed mainly of synthesized low frequency bass notes often played with a simple, repeating melody. Bass tests are used to test the low end, or bass response, of audio systems, particularly loudspeakers and amplifiers...

s use sub-bass frequencies which are used to test or to demonstrate the capabilities of audio equipment. Very few subwoofers can reproduce sound below 30 Hz at high volumes.

Sub-bass energy is popular in dance music

Dance music

Dance music is music composed specifically to facilitate or accompany dancing. It can be either a whole musical piece or part of a larger musical arrangement...

 , where the low frequencies involve energy from the kick drum, the bass guitar

Bass guitar

The bass guitar is a stringed instrument played primarily with the fingers or thumb , or by using a pick....

 and electronic synthesizer

Synthesizer

A synthesizer is an electronic instrument capable of producing sounds by generating electrical signals of different frequencies. These electrical signals are played through a loudspeaker or set of headphones...

s. In particular genres such as dubstep

Dubstep

Dubstep is a genre of electronic dance music that originated in south London, England. Its overall sound has been described as "tightly coiled productions with overwhelming bass lines and reverberant drum patterns, clipped samples, and occasional vocals"....

 and drum and bass

Drum and bass

Drum and bass is a type of electronic music which emerged in the late 1980s. The genre is characterized by fast breakbeats , with heavy bass and sub-bass lines...

 often feature the whole bass-line reproduced in sub-bass frequencies. Much experimental music

Experimental music

Experimental music refers, in the English-language literature, to a compositional tradition which arose in the mid-20th century, applied particularly in North America to music composed in such a way that its outcome is unforeseeable. Its most famous and influential exponent was John Cage...

 uses sub-bass, in particular drone music

Drone music

Drone music is a minimalist musical style that emphasizes the use of sustained or repeated sounds, notes, or tone-clusters – called drones. It is typically characterized by lengthy audio programs with relatively slight harmonic variations throughout each piece compared to other musics...

, where the majority of the sound can often be in the sub-bass range. Often, hip hop

Hip hop music

Hip hop music, also called hip-hop, rap music or hip-hop music, is a musical genre consisting of a stylized rhythmic music that commonly accompanies rapping, a rhythmic and rhyming speech that is chanted...

 and rap songs feature much sub-bass.

Sub-bass drops or slams are sometimes used in heavy metal

Heavy metal music

Heavy metal is a genre of rock music that developed in the late 1960s and early 1970s, largely in the Midlands of the United Kingdom and the United States...

, particularly most common in deathcore

Deathcore

Deathcore is an extreme metal music genre that combines elements of death metal with elements of metalcore or hardcore punk, or both. It is defined by an "excessive" use of death metal riffs, blast beats and use of hardcore punk breakdowns...

, where they are used to start the beginning of a breakdown. This is seen in bands such as Chelsea Grin

Chelsea Grin (band)

Chelsea Grin is an American deathcore band from Salt Lake City, Utah. Formed in 2007, the group is currently signed to Artery Recordings and have released one EP and two full-length albums...

, Job For A Cowboy

Job for a Cowboy

Job for a Cowboy is a American death metal band from Glendale, Arizona. Formed in 2003, the band's debut album Genesis was released in 2007, peaking at #54 on the US Billboard 200 and selling 13,000 copies in its first week of release. The second album, 2009's Ruination, sold 10,600 copies in...

, and Whitechapel

Whitechapel (band)

Whitechapel is an American deathcore band from Knoxville, Tennessee. The group comprises vocalist Phil Bozeman, guitarists Ben Savage, Alex Wade, Zach Householder; bassist Gabe Crisp and drummer Ben Harclerode. Their band name is derived from a district in the built-up inner city of London, known...

. These are meant to give the listener a feeling of awe and force.

Other uses

In southern gospel

Southern Gospel

Southern Gospel music—at one time also known as "quartet music"—is music whose lyrics are written to express either personal or a communal faith regarding biblical teachings and Christian life, as well as to give a Christian alternative to mainstream secular music...

 groups or a cappella

A cappella

A cappella music is specifically solo or group singing without instrumental sound, or a piece intended to be performed in this way. It is the opposite of cantata, which is accompanied singing. A cappella was originally intended to differentiate between Renaissance polyphony and Baroque concertato...

 contemporary Christian groups, "sub-bass" is an informal term for octavist

Oktavist

Octavist or oktavist is a type of male singer who sings an octave below the normal bass part, especially typical of Russian Orthodox vocal music. This voice type has a much lower vocal range than what the Western school of music terms "basso profondo". Indeed, a man of this voice type sings a full...

, a specialized basso profondo. These singers often sing below the F clef and sometimes employ vocal fry to achieve even lower sounds.