Friday 15 April 2022

Imitative Sound Design For Synthesizers...

In a recent thread on the VI-Control forum, Alessandro Arcidiaco asked about resources for learning imitative sound design - making the sounds of acoustic instruments by electronic means (synthesizers et al). Here's my (edited) response:

Photo by Karim MANJRA on Unsplash

Most 'how to...' 'synthesizer' articles talk about how to create 'classic' synthesizer sounds, and Gordon Reid's magnum opus 'Synth Secrets' series (in Sound On Sound) covers that in a lot of depth: 

There are quite a few articles in the series that talk about creating realistic sounds (wind, brass, strings, drums, etc.), often used as an illustration of the uses of specific synthesis techniques. (There are also various books from the end of the 20th Century, assembled from 'Electronic Musician' articles from Jim Aikin, Marc Vail, Craig Anderton et al covering much the same material, again with some coverage of imitative techniques, but I can't recall a specific 'imitative' series... So, my short answer is that I don't know of the 'definitive' answer - but that doesn't mean it doesn't exist!) (Bio of Jim Aikin) (Jim Aikin's web-site) (Marc Vail's web-site) (Craig Anderton's web-site)

(It is quite interesting to see how a previous generation of 'people who reviewed and wrote about synthesizers' is represented by magazine articles, reviews, books and web-sites, whereas the current  Loopop, Benn Jordan, Starsky Carr, etc. generation are all very active on YouTube...)

You can see this non-specific-ness about imitative synthesis in my 'Practically FM' series (in Sound On Sound magazine many decades ago), which kind of works towards 'imitative', but it tends to show more about how FM can produce synthesised, only-slightly 'imitative' sounds:

For techniques where 'imitative' is baked in, then people seem to resort to analogies. This article on Physical modelling quotes me here and there: 

Which leads to my take on physical modelling: 

This is again more about the modelling than the actual synthesis. One very good pointer to the problems of modelling is Yamaha's percussive physical modelling (Karplus-Strong et al) VP-1 synthesizer from 1994 that never made it from prototype to real world - there's an amazing prototype in the Yamaha 'Innovation Road - History of Products' museum in Hamamatsu, Japan...

Technics made an amazing physical modelling synth in the mid 90s that you've probably never heard of... (The SX-WSA1 - I reviewed it for Sound On Sound, Mike Metlay reviewed it for the Computer Music Journal) (my review) (how to miss a bargain) (From the CMJ - behind a paywall)

(Modern VSTs that use modelling for pianos have seen better success in this space - as with much of technology, timing is vital: too early and the tech/knowledge isn't up to it, too late and the tech/knowledge is available to all... Feel free to do a Google search on 'Piano VST physical modelling'...) 

What is harder to find information on are the more formal, academic, methods. One example would be Residual Synthesis (aka Analysis/Synthesis or A/S), which takes the sound that you want to imitate, and subtracts it from a close imitation to give a 'residual' - the difference between the wanted sound and the synthesized version. That residual is then used as the starting point for a second imitation, and this continues iteratively until you have as close an approximation as you want. The trap here is that it can be very difficult to cope with the changes in timbre from dynamic playing, and it is easy to get bogged down in deconvolution problems that diverge, so there may not be an easy way to create all of the different residuals for different velocities. It's a bit like curve fitting: choose the wrong type of curve and you may be able to fit some of the data, but if you get new data, then you may find that the curve can't be persuaded to fit at all! I did an AES paper on a variant of residual synthesis back in 2018.... (The AES paywall this time...)

The 'elephant in the room', in my opinion, is that there's an easy escape route, and it started when synthesisers and samplers began to converge with instruments like the Roland D-50: suddenly you had something that produced sounds from hybrid sources: samples (often alarmingly short!) where you needed that characteristic 'fingerprint' for a specific type of sound; and synthesis for when you wanted to augment, enhance, accompany, sustain or alter the sound so that it had a mixture of realistic and synthetic. S&S instruments used these 'Sample & Synthesis' techniques to give huge numbers of presets that passed the 'Mom' test (Would your Mom say that it sounded like what the preset was called?), and layered variations or synthesised sounds on top to give variations. Depending on your viewpoint, these are either hyper-real, or sub-real, but they were easy to produce, and the end of the 20th Century saw huge numbers of boxes with large numbers of presets and lots of sample ROM inside them.

Roland D-50 (My review)

Interview with Ikutaro Kakehashi (My Interview with the head of Roland) 

You can seen how appealing the S&S technique is by considering the E-Mu Proteus, which started out as an enormously successful 'orchestra in a box' (probably one in just about every studio at one time), but which gradually morphed (samples and filters!) over time into providing lots of samples of synthetic sounds, on ROM cards that could be put into slots to create boxes containing vast numbers of sounds (My E-Mu PX7 has all four slots full of 32MB ROMs, for example). 

A quick timeline of E-Mu 1U rack-mounting sample players...

A table of the 32MB ROMs would follow a similar timeline, although not all ROMs got a dedicated player... (E-Mu History)

Yamaha's S&S synthesisers (the current Montage, for example), uses lots of samples to imitate sounds (often layering several variations, and using different samples for different dynamics), but at the same time, has a very powerful FM synthesizer inside which can be used to imitate, augment and enhance the samples. What do you hear a lot of the time from a 'factory/stock' Montage? Samples augmented by other samples... and by FM...

(This is more of an observation about the way that synthesizers are 'voiced' nowadays, and is not a criticism! I really love my Montage 7, and have made quite a few FM patches - a few of which are on SoundMondo...)

Turning synthesis around, and writing a series of articles that start with imitative techniques, is a big task (requiring lots of time, lots of research, and lots of painstaking skill and effort), and the 'Mom' test is fighting you all the way, because S&S instruments (I would count a lot of sample replay devices and sample libraries as being in that set) pass easily, and rather like the 'Uncanny Valley' in making CGI people, it only needs one minor inconsistency for your brain/ears to detect the synthetic nature, and you are back to square one (a 'football commentary on radio' reference, it turns out!)... Getting a real trombone player to listen to a few 'brass' sample libraries can be very illuminating... (The 'Uncanny Valley'...)

So, you now have a partial view of what I have been doing in electronic music from the early 1970s to the present... This is all my biased, personal opinion based on how I lived through those times. Your opinion can differ, of course...

The 'Mom' Test

Easy! Just ask someone considerably older (wiser, more travelled, more experienced, maybe someone who listens to more Jazz or Classical music...) than yourself to listen to a sound made by your synthesizer, VST, etc. Then ask them what the sound was. If it was called 'PanFlute47b' and they say: 'It is a flute!', then you pass the test. If they say: 'It sounds kind of like a flute type of thing...', then you get a partial pass. If they say: 'Is this another of your synthesizery sounds?', then you fail. 


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