This definition is not “beat” we normally think of with the rhythmic speed at which a song is played. Another definition of beat is related to acoustics. In music acoustics, a beat is the interference pattern between two sounds (wavelengths or sine waves) of slightly different frequencies perceived as a periodic variation in volume whose rate is the difference of the two frequencies. For example, when tuning a a stringed instrument (guitar, bass, etc.) with harmonics, it is the warbling sound the two different harmonics make with each other that eventually is no longer heard once the two strings are tuned so that the harmonics match. Once they are in tune the beat is no longer heard.
Saturation, specifically magnetic tape saturation, is an effect that happens naturally due the physical limit of the amount of magnetism a magnetic tape can hold. Attempting to add a stronger signal than the tape can handle results in a form of clipping distortion. Due to the relative power levels and natural interactions of sounds at different frequencies, lower pitches tend to saturate more than higher ones. Combining this with magnetic tape’s tendency to “self-erase”, particularly at higher frequencies, and it creates a “warm” sound that is different than most other forms of distortion. Today, saturation, like most effects can be and is modeled in many DAWs and plugins.
A breakdown is a section of a song where some or all of the instruments play a solo part, often as refrain or variation of musical themes established earlier in the song. It serves as a third section to add flavor to the normal Verse-Chorus structure, and can be considered a type of Bridge section.
This is a popular composition element in Bluegrass and Heavy Metal, but may have originally been invented by Disco DJs. They would drop all other instruments from the mix, except the drums, while they arranged their equipment for the next track. This removal of all tonal sections gives them room to introduce a new melody without having to worry about the old key signature or themes.
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