A Bass Song is a piece of music that contains low frequency notes, which is called bass. Bass notes can be acoustic, but within the term "bass song" they are usually synthesized, typically sine waves or very similar. Most of the time the term "bass song" alludes to a hip hop or rap song, but there are also reggae, techno, dubstep and other electronic songs that fall under this category.
These songs are usually played in, and sometimes specially designed for, automobile sound systems with one or more subwoofers.
Sometimes, a bass song is a specifically designed track for a certain arrangement of subwoofers or loudspeakers to achieve the maximum sound level possible.
A bass song is different from a bass test. A bass test is a recording where bass is the main point of the track, whereas in a bass song, the bass is still very prominent, yet remains supplemental to the rest of the song.
Many bass songs utilize sub-bass frequencies ranging from 25 Hz to 80 Hz, which is the general operating range for a car subwoofer setup. A ported subwoofer enclosure's tuning frequency is usually within this range as well.
A low frequency bassline in a bass song can be made by applying a low-pass filter to an acoustic bass instrument, or it can be created using a synthesizer.
Two often-used bass songs in the rap category are Put On by Young Jeezy and A Milli by Lil Wayne. Both of these songs have peaked at #1 on the US Billboard Hot Rap Tracks.[1] Put On switches between four different frequencies of bass, the lowest being about 25hz, and consistently uses it throughout the whole song. A Milli makes use of only one bass frequency, but alternates on and off throughout the song.
There are a plethora of other popular bass songs in the rap genre, and a multitude more when considering other genres, but these are just two that are commonly used in a car audio environment.