How High the Moon

To simply suggest that Les Paul was an important figure in modern music would be like saying that Hugh Hefner had a little something to do with the importance of boobs. The man revolutionized the direction of guitar playing around the world, and single-handedly developed recording techniques and tools that paved the way for the sound of modern music.
Most of which he did in his own garage, without any formal engineering knowledge.
Already an accomplished jazz, blues, and country guitar player in the 1930's, having recorded with Nat King Cole, Bing Crosby, The Andrews Sisters, and his own trio -- he began to experiment with ideas aimed at improving his own sound. Unhappy with the sound of acoustic guitars at the time, he took a 4" x 4" piece of wood, attached a guitar neck, pickup, and bridge onto it.
This would become the world's first solid body guitar.
Most electric guitars used in modern music, whether it be rock, jazz, R&B, or country are direct descendants of that instrument.

He then went on to work on a similar design in the early 50's with the Gibson guitar company, who named their guitar "The Les Paul" -- which has gone on to become one of the most popular and iconic guitars ever sold. Les Paul's are still sold and played today, instantly recognizable by their shape and sound.

But beyond this was Paul's designs for studio recording, which include the development electronic delay/echo effects, phase shifting, track overdubbing, and multi-track recording.

Before Les Paul began experimenting, most albums were recorded live with only one or two microphones placed strategically in the middle of a group -- a technique that provided a unique sound, but often left quieter instruments lost in the shuffle.

Paul advocated multi-tracking, which enabled players and singers to record parts individually and then mix them back together to create a single recording that offered each individual instrument it's own room in the mix.

But Paul took it a step further. By varying the speeds of each recording, he could create multiple-part harmonies with his instruments that would not have otherwise been possible -- enabling him to mimic the sounds of big bands and even orchestras when he wanted to by himself. He then applied the same theory to recording a singers voice (usually that of his former wife, Mary Ford) -- leading to a string of hits for the two in the late 1950's.

- Notice the wall of tape decks that he's harmonizing with in real time. Not an easy trick at all.
This technique of auto-harmonizing is the direct progenitor of Auto-tune, which
(for better or worse) is all the rage right now in modern pop and hip hop music.
All of these ideas were fine for creating quality recordings, but Paul wanted the ability to be portable -- so he created this little black box called "The Les Paulverizer" which enabled him to record and layer these harmonies automatically, giving him the flexibility to perform multi-part harmonies (ranging sometimes in excess of 20 individual parts) live. He even began showing up on stage with a little black box attached to his guitar that he would appear to perform this technique with:

The box on the guitar was later revealed to be nothing more than a stage prop, with the actual device off stage -- but the technique was real, and it was one that Paul used frequently.
All decades before the advent of digital sound processing.
All of these things are elementary to any sound engineer these days, but at the time were nothing short of black magic.
Which is to say nothing of the fact that the guy could absolutely shred.

- RIP Les (June 1915 – August 2009). Thanks for the music.

[Listening to:  Cindy Blackman - "Green Dolphin Street" ]