Editing Frequency modulation synthesis (section)

=== 1990s ===
==== Free use of FM after the patent expiration ====
With the expiration of the Stanford University FM patent in 1995, digital FM synthesis can now be implemented freely by other manufacturers. The FM synthesis patent brought Stanford $20&nbsp;million before it expired, making it (in 1994) "the second most lucrative licensing agreement in Stanford's history".<ref>Stanford University News Service (06/07/94), [http://news.stanford.edu/pr/94/940607Arc4222.html Music synthesis approaches sound quality of real instruments]</ref>

Today, FM is mostly found in software-based synths such as [[Native Instruments]]' FM8 or [[Image-Line]]'s [[Sytrus]] plug-ins, but it has also been incorporated into the synthesis repertoire of some modern digital synthesizers, usually coexisting as an option alongside other methods of synthesis such as [[subtractive synthesis|subtractive]], [[sample-based synthesis]], [[additive synthesis]], and other techniques. The degree of complexity of the FM in such hardware synths may vary from simple 2-operator FM, to the highly flexible 6-operator engines of the [[Korg Kronos]] and [[Alesis Fusion]], to creation of FM in extensively modular engines such as those in the latest synthesisers by [[Kurzweil Music Systems]].{{Citation needed|date=July 2019}}

==== Later use of FM and other technologies: Realtime Convolution & Modulation (AFM + Sample) and Formant Shaping Synthesis ====
The [[Yamaha SY99]]<ref name=YamahaSY99>{{cite web |title=Yamaha SY99 spec |url=https://jp.yamaha.com/products/music_production/synthesizers/sy99/specs.html |language=Japanese |website=[[Yamaha Corporation]]}}</ref> and [[Yamaha FS1R|FS1R]]<ref name=SOS1998>{{cite magazine |first1=Debbie |last1=Poyser |first2=Derek |last2=Johnson |date=1998 |title=Yamaha FS1R - FM Synthesis / Formant-shaping Tone Generator |url=https://www.soundonsound.com/reviews/yamaha-fs1r |magazine=[[Sound on Sound]] |issue=December 1998}}</ref> synthesizers marketed their highly powerful FM abilities as counterparts to [[sample-based synthesis]] and [[formant synthesis]] respectively. New hardware synths specifically marketed for their FM capabilities disappeared from the market after the release of FS1R in 1999, {{Citation needed span|however, well-developed FM synthesis options are a feature of [[Nord Lead]] synths manufactured by Clavia, the [[Alesis Fusion]] range, the [[Korg Oasys]] and [[Korg Kronos|Kronos]] and the Modor NF-1. Various other synthesizers offer limited FM abilities to supplement their main engines.|date=July 2019}}

The FS1R had 16 operators, 8 standard FM operators and 8 additional operators that used a noise source rather than an oscillator as its sound source. By adding in tuneable noise sources the FS1R could model the sounds produced in the human voice and in a wind instrument, along with making percussion instrument sounds. The FS1R also contained an additional wave form called the Formant wave form. Formants can be used to model resonating body instrument sounds like the cello, violin, acoustic guitar, bassoon, English horn, or human voice. Formants can even be found in the harmonic spectrum of several brass instruments.<ref name="zollinger2016" />