Most composed music is sectional. And I think we've talked about structure here. But what about transitions? What do you use to connect one section with another to create a seamless experience for the listener.

Sometimes, I'll just use silence and this seems to work well as it prepares the listner for new music to come. Other times, a modulation works nicely.

Your thoughts as always are welcome.

You have described the two main methods. The abrupt transition; this works especially well in secional pieces like songs with verse and chorus. One can have a bridge passage, maybe a few measures or even quite long. Also, one can joint the parts by having the latter measures of the first section merge smoothly with the opening measures of the second. This makes for a seamless transition.

The method used depends on the piece. I've found that in pieces with an ABA structure work well if the A-B is rather abrupt but the B-A transition is smooth. This is particularly if the keys are tonic-dominant-tonic. It's sometimes more dramatic to move A-B smoothly so that the B-A transition becomes more prominent.

In 18th and 19th century sonatas (and similar pieces), the transition may be used to introduce new thematic material.

Speaking from experience, it's rare that I designate a particular passage as "connective tissue". Rather, sections (must) flow smoothly from one to another and, indeed, the "less ordered" end of the section largely determines what comes before or after it. A danger of designated "transitions" and rigidly defined "core" passages is that passages don't always lend themselves to make the listener "desire" further musical idea: they are "preventive" to certain musical modifications.

How I "fill gaps" relate to how I compose globally. Once I have an 'A' idea, the "less ordered" end of 'A' often determines what 'B' is going to be like. Thus I end up with 'A' and 'B' as already as two connected passage, and from that, what constitutes the 'core' of 'A' or 'B' can be easily seen by inspection, and the rest may be arbitrarily desginated "transition" (although musically, really, they're integral to both passages as a whole).

Because I usually have the whole piece more or less structured (in terms of momentum, "majorness", "minorness", "sharpness", "flatness", "awayness", "homeness", "familiarity-but-not-quite-homeness" as a function of time) before I begin (allowing maybe two or three possible alternatives), I inspect whether 'A' and 'B' lend themselves naturally to the desired parameters and - if not - how to improve them. The modification often results in new ideas that are not necessarily temporally distinct (i.e. the modified 'A' has a new musical idea but is still recognisably 'A'). Now, I sometimes try these new ideas in isolation, treating them as if they're independent of the idea they were derived from. This ends up with a lot of "tools" I can use, and putting these together bearing in mind my reference structural template, I often end up filling all the necessary "gaps" without thinking of them as transitions, and these "gaps" intelligently refer to
other ideas in the music. This way it is possible to prevent gaps that feel "out of place".

I thought I should also mention truncation and extension, two "tricks" I often use in developing a musical idea. Let's say 'A' is 8 bars long. By "truncating" it at bar 6 and finding it an alternative development of bars 7, 8 (and beyond?) new musical ideas can be introduced. This requires me to think, for example, "How could I rewrite 'A' so that it achieves more of the 'awayness'?" As for extension, let's say 'A' ends in a IV-V-I progression. I could change that into IV-V-vi progression. The interrupted cadence prompts for "more" musical ideas.

Transitions are seamless when they feel demanded and intended. Make your preceding passage demand a transition, and make your transition conform with the musical ideas you have/are going to introduced.

My transitions are often short development sections, I use fragments of the preceding theme (or some other theme from the piece) to move from one section to the next. Sometimes I use a transfomtation technique where theme A gradually transforms into theme B through a few intermidiate steps. I might also do abrupt transitions where a new theme without warning interrupts the previous section, or other kinds of transitions depending on the context.

What kind of transitions I use also depends on the time scale. In a short 2 minute piece, transitions will probably be short, if they exist at all. But in a >10 minute single movement unit there will have to be longer transitional sections.

I tend to like smooth transitions. In other words, I introduce a new idea little by little, and remove the old idea little by little. This is "seamless," but it can be really subtle, so it doesn't work for every piece!

Other times I just try to think of a cadence. By that I do not mean a V-I progression (since most of my music is not tonally based anyway), but rather some kind of gesture to put a "period" or "comma" to that section. This could be building up intensity and suddenly stopping, building intensity directly into a new idea, winding down the intensity to a new idea, or winding down to pause for a moment before starting something new.

Great contributions to this thread all! I didn't expect to get so many varied responses. And so much helpful info! Keep em coming!

Out of curiosity I looked through a heap of my old romantic piano compositions from twenty to thirty years ago. Mostly I seem to have just stuck ferocious cadenzas in between more or less melodic sections. On one level it was probably an excuse for not thinking, a substitution of energy for substance, but for that particular sort of music it doesn't sound too bad at all and makes it fun to play.

I don't remember which Mozart sonata I got this idea from, but in one of the variation movements he has a set of variations where the "connecting tissue" between variations is different every time. So in one of my own variation sets (unfinished), I wrote a different chord progression each time as the "connecting tissue" between variations:

midi file

More common in classical, but also possible in other styles is the idea of "Developing Variation." It's a term coined by Schoenberg to describe something that Brahms often does. He'll latch on to a seemingly unimportant or secondary idea and let it emerge as a main theme.

A good example is in the Bb Major Sextet, where the cadential figure for the first theme becomes the second theme. It's quite ingenious and works very well.

I've tried something similar in some pieces - I'll take a countermelody and have it become the main melody for the next section.