Some time ago I wrote that its hard to digitally simulate the guitar, because its hard to realize guitar background noise in digital simulations. Now I've started to learn a new, completely analogue instrument and have found other important features of original instruments that make them stand out from their virtual copy. With the help of the saxophone I would like to introduce some further limits of digital music with this article, which are existant, but they are very manageable and can be overcome with a little effort. But for this you should take a look at the instrument you are going to simulate.
Anyone who starts playing the sax immediately realizes that making a sound is not that easy. More specifically, it requires good guidance, in the best case even professional support from a music teacher, for making sound with it. Even if you've played the first note, it will take a while to play melodies. The breath is not strong enough in the beginning to play a melodic passage in one piece. This brings us to the first limit of an analog instrument: the human being. Humans have physical limitations. One of them is about muscle power. It manifests itself in the breath (diaphragm and other components), but also in the embouchure. The embouchure is a relevant variable at saxophone playing. It is the mouth's position on the mouthpiece that significantly affects the sound. The necessary tension must be well trained by a saxophone player, otherwise it decreases and the sound will change. Generally the embouchure transforms during the music piece and changes the sound.
On the other hand, a digital pardon can produce the same sound at any time, for as long as one would like it to be. It does not breathe, it does not need muscle power or any other human abilities. It could keep the perfect tone. But that makes the music rigid, because the changes we perceive in natural recordings through these limitations of human capabilities are essential to our natural understanding of music.
Also the rest of physics, apart from humans, also limits an instrument. A limitation of the saxophone are the flaps. For some tone changes, several of them are to be operated, and it takes a lot of practice that there are not other tones apearing in the recording that only need only a portion of the flaps for the desired tone. The change is minimal audible even with good players. The change of several flaps is necessary because the instrument needs different air outlets for different tones, so that the mood fits. The digital emulation does not work with flaps, it starts the sound directly. So the effect would have to be built into the digital music notation so that the physics-related effect comes to light digitally. For this, a good knowledge is necessary, where to change which flaps, because he just does not occur in all places. Another effect is different lengths of time until the sound starts depending on the pitch. I only know that these exist, but I have not quite figured out how strong they are. That might be something I should have to work on to improve the emulated sound.
Even the notes of an instrument adapt the instrument. Although the musical notation continues to function as one would expect from other instruments, there are other dialect-like conventions that exist in the notation for each instrument. For example the sax has a different tuning than the piano. What is a C in the alto saxophone is an es at the piano. For this reason, other keys (related to the piano keyhole C) are common for saxophone pieces, and other instruments have to adapt (the piano does not play "easy" in C major, but in E flat major).
Also known things of musical notation have a different interpretation than for other instruments. On the saxophone, these are the slurs. At the piano I played those by hitting each key (which his own attack) leaving no gap between them. With the saxophone you can really bind them, but you have to make sure that other notes are made with an attack. Who emulates the instrument can set digital notes at will, without paying attention to the instrument itself. He can play the saxophone like he would play a piano. But if you learn about the notation, you can shape the digital notes so that they follow the conventions and keep the realistic sound of the original instrument.
The limitations mentioned limit the possibilities of the analog instrument. These influence the sound, the way of playing, the flexibility and each other.
They eliminate things that a digital instrument can do without difficulty because it can either change the parameters at will, or hold them so rigid that they simply can not adapt. Because on the digital site you can work with equalizers, filters, reverb and so on independently or you can work without these things. A sense of the parameters of a physical instrument provide more realism in playing a digital instrument. Anyone familiar with the analogue device knows what does not fit instead of simply have a feeling of "something sounds wrong". Of course, clinging to real parameters limits the great freedom that the digitization of making music brings us, and the freedom should not be circumvented at all. In order to translate this freedom into good creativity, it is advisable to deal with the original instrument, and be it so that you learn to play it. Of course, this is a lot to ask, because sometimes you can then learn to play it right away and make a real recording. But a bit of clue by reading some information about it could change a lot. Because then we come from randomized parameter variation to targeted sound shaping. With this knowledge you could overcome the problem of the great flexibility of digital instruments and could learn to create the sound you want to have.
Zimmermann, Dr. Christian, VL Human-Factors Engineering WS 2017/18 and SS 2018, LMU Munich
And own experiences