I’m listening to So Inagawa again this morning, today it’s his track Count Your Blessings which is very lovely. The track starts with a simple filtered chord progression which in spite / because of it’s simplicity I find very compelling. It’s got me thinking about why this is, and why filter movement in particular is such an affecting thing in music, specifically electronic music, although now it’s crossed into other genres as part of the ‘electronification’ of all music. Drake practically trademarked the ‘wistful low pass filter breakdown’ as a trope in R&B, injecting it into the continua of urban pop music over the past decade or so. But in house and techno the idea of frequency manipulation as a leading vector of change and interest has been around for decades.
So what am I talking about here? Lots of uninitiated folks talk about ‘filters’ as a kind of all purpose shorthand for ‘things that process audio’, partially translating the language of Photoshop and Instagram to the world of audio. But in audio signal processing a filter has a specific meaning. It’s a device which is used to shape the frequency content of an audio signal, usually by removing certain frequencies and boosting others. A low pass filter is a common example. A low pass filter allows low frequencies to pass through while removing frequencies above a cutoff frequency. The cutoff frequency can be moved over time to transform the signal dynamically either by a person performing a filter sweep or automatically, based on an envelope control. This kind of automatic filter movement is used to create the bow-wow sounds of wah guitar in funk music for example. Dubstep is also a genre of music strongly shaped by filter movement, with most of it’s trademark alien bass sounds produced through some kind of automated filter movement. If you’re trying to determine if a sound is shaped by a filter you can try to make it with your mouth, the open or closed shape of our mouth serves as a natural filter. If you start off humming then open your mouth slowly into an ‘aah’ sound you can produce a filter sweep type effect.
House and techno being predominantly synthesizer generated and focused heavily on sound as a structural ingredient discovered the magical properties of changing filters over time early on. In fact the entire genre of ‘acid’ house or techno, centered around the Roland TB303 is basically filter music. The squelchy evolving synth line that rose to prominence with the release of Phuture’s ‘Acid Trax’ 12″ in 1987 thrust the resonant filtered synth line to center stage, making it the main ingredient in a new genre of dance music. The TB303 was designed to be a bass line synthesizer by Roland but was terrible for it’s intended purpose. What Phuture discovered with Acid Trax was that by treating it less as a bass instrument and more as a lead line developing across the frequency spectrum that it could capture the listeners interest in a hypnotic yet energetic way. Acid went on to become a global movement, particularly popular in Europe. To this day it’s hard to overstate the cultural significance of acid in the European rave culture. People go absolutely crazy for it when it comes on, it’s intricately bound with the core elements of house and techno and a certain utopian moment in rave history.
Acid is interesting because it’s minimalistic, but not in the tasteful hypnotic lock in of music like Inagawa’s. It’s harsh, repetitive and filled with peaks and troughs. The narrative and energetic arc of the music is almost completely transmitted through the development of the frequency character of the 303 line, mostly via the adding and subtraction of high frequenices. This energetic rhythmic minimalism is part of the legacy of African American music with a clear influence of funk and disco, but rendered in the harsh experimental palette of minimalist synthesizer music. Like so much of the history of Black American musical output, it represents a fascinating collision of musical aesthetics, technology and history. There is probably some psychoacoustic analysis of frequencies and their effect on the body and mind to be done here, though I’m not particularly qualified to do it. All I can say is that from my subjective experience I find the experience of listening to frequencies transforming over time to be both cerebrally fascinating and emotionally affecting. Years of DJing tell me that I’m not alone in this, though I’m not sure if anyone fully understands why.
