Tunes published in 1923 will be entering the public domain

United States copyright law is quite restrictive as compared to many other countries. According to the provisions of the Copyright Act of 1976 and the Copyright Term Extension Act of 1998 (aka "Mickey Mouse Protection Act"), works published or registered before 1978 remain under copyright for 95 years.

Since the passage of the 1998 Mickey Mouse Protection Act, the cutoff date for works entering the public domain has been 1922, with any works published in 1923 or later remaining under copyright. Beginning in 2019, the clock will start running again, with each new year bringing one more year of songs and other works into the public domain. Over the next 20 years or so, most "Golden Age" jazz standards will lose copyright protection.

As of January 1, 2019, copyright will expire for these works published in 1923:

King Porter Stomp
Who's Sorry Now
Tin Roof Blues
Yes! We Have No Bananas
The Charleston
Nobody Knows You When You're Down and Out
I Cried for You

In 2020, these works from 1924 will become public domain:

Everybody Loves My Baby
Fascinating Rhythm
I Want to be Happy
I'll See You in my Dreams
It Had to be You
The Man I Love
Rhapsody in Blue
Somebody Loves Me
Tea for Two
Oh, Lady Be Good

Depending on your tastes, you may find some of these songs to be a bit dated. But the 1920s and 1930s were a period of rapidly increasing musical sophistication. In a few more years we will start to see some of the better tunes by Gershwin, Cole Porter, Jerome Kern, et al.

Unless, of course, Congress comes under corporate pressure again, and passes another extension like the 1998 Mickey Mouse Protection Act.

Many other countries have shorter terms of copyright; one common formula is the life of the author plus fifty years (see this table). For example, in Canada you will be able record songs written by Wes Montgomery (d. 1968), without paying royalties.

Some articles to check out regarding copyright:

A Landslide of Classic Art is About to Enter the Public Domain (The Atlantic)

For the First Time in More Than 20 Years, Copyrighted Works will Enter the Public Domain (Smithsonian.com)

These 1923 Copyrighted Works Enter the Public Domain in 2019 (Lifehacker.com)

Copyright Law of the United States (Wikipedia)

Hermeto Pascoal’s improv lessons

A fascinating article from the Ethnomusicology Review: Notes from the Jabour School: Multidimensional harmonic models for improvisation, composition and arrangement from Hermeto Pascoal’s Grupo in Rio de Janeiro, by Jovino Santos Neto.

You really have to read this yourself, but I'll try to summarize.

Jovino, an articulate writer, discusses his experiences as a young musician playing with Hermeto Pascoal's ensemble, particularly Hermeto's method of teaching improvisation to his musicians. An excerpt:

The first thing that Hermeto taught us when improvising over chords to ‘Campinas’ was to write above each chord symbol a number of triad options. So, if a chord was a C major 7th, we would write the symbols for G, E minor, D and B minor. These triads are components of the C Lydian mode. If a chord was a C minor 7th, we would write the triads Eb, Bb, D minor, F. These are components of the C Dorian mode. For each chord type there are between 2 and 5 triad options to be explored. However, instead of having us learn linear scales and modes, Hermeto would inspire us to create simple, intuitive melodies based on those triads.

This comes across to me as an adaptation of the "substitution by thirds" and "upper structure" approaches. But the last sentence above is essential. 

Jovino goes on to describe his own expansion of this perspective:

Even though we tend to treat chords as individual entities or motionless objects, in reality they connect to and inform all the musical material surrounding them, so it would be more appropriate to consider chords as verbs, (which denote actions), rather than nouns, which denote objects. We can then visualize any chord as a cloud of possible musical actions, with an ‘atmosphere’ of triads surrounding it. I found it convenient to use three dimensional images as a visual aid to enable the multi-sensorial perception of harmony...

...Furthermore, I find that even better than using abstract Platonic solids as sources of imagery for musical reference, we can instead focus on shapes commonly found in Nature. Trees, for instance, can very effective models for conceiving harmonic entities. As land-dwelling beings, we think of trees as stationary objects, but somewhere in the inner core of our brains, we can still visualize trees as stations along a pathway of travel like our canopy-dwelling ancestors.

As I mentioned, you really have to read this article in its entirety. In fact, I think I'll go back and read it a few more times, myself.

Note: Jovino will be presenting a lecture on "The Harmonic Forest: Musical Structures Heard as Trees" on Jan. 21, 2019, at the Seattle Art Museum. Here's a link for ticket information.