I tend to get caught up in issues of notation, so it’s time for me to step back. Keep it simple.
If you are a composer looking for a special kind of sound, but aren’t sure how to notate it, your solution may be as easy as adding a bit of text describing what you want.
This seems like a no-brainer, but many composers feel compelled to add prescriptions rather than descriptions. A prescriptive direction tells the player how to execute the effect and does not describe the intended result. Unless you are a player of the instrument in question, avoid prescriptive indications like the plague. Here is an example: a prescriptive indication might say “use lots of air”, or “tight embouchure”.
A more useful, descriptive indication for “use lots of air” might be “match the sound of the string harmonics” or “imitate a bamboo flute”. Matching string sounds and producing bamboo sounds are two very different techniques, but both using an airy type of sound, so it is helpful to have a descriptive indication to know which of these types of airy sound the composer might have in mind.
The prescription “tight embouchure” might be “thin, reedy sound” or “like a buzz saw”. Again, very different means of production, so a description is helpful.
I hope this has made your composing day a bit easier 🙂