This is the reason to advocate for music--it is critical for lifelong brain health. Imagine if this man had not had such a rich musical background:

New---findings from four research studies on the impact of the arts in schools for at-risk youth

MENC advocacy resources
There are many resources here.
The "Support Music Database" on this page is probably a good resource for making specific arguments.

Here are some research articles on this topic. If you cannot find the reference information (e.g., journal, date, pages, etc.), then look up the authors and the title of the article on google and you will probably get the bibliographical info you need.

Music education and academic achievement.
This article is not very positive in terms of our needs. Yet it is a great source for the arguments that will be used against you. When the article says there is no proof of this or that, have a look at the methodology of the research. For example, one study they mention (Stringer 2004) provided kids with two 25 minute sessions of music instruction for a total of six weeks, which is a ridiculously small amount of time over a ridiculously short period of time. So, it is hard to take any of their conclusions too seriously. Also, you can use the bibliography of this study for more articles you might want to read.

This study involved 25,000 kids over ten years. You can take these conclusions pretty seriously and it is definitely the epitome of convincing research data.

This article is not research in itself but it does explain the ways in which music supports literacy.

This article compares music listening and music lessons. The important thing about this article is that it says that lessons make a difference but it suggests that the effects are small. The importance of this is to make sure you are careful to avoid "over" reporting of effects--because then your argument won't work. It's probably better to go ahead and use these statistics but bolster the argument with the specific literacy information (Wiggins) and also with other arguments below.

This article is about something extremely important and also that is a strong argument in favor of music education, and that is how music education can keep disengaged kids going in schools. There is a huge drop out rate in American schools and music is something that can help to reduce that.

Another research study about the positive effect of music education on academics.

Music teachers' experiences with advocacy for music education--might be helpful.

More info about music education advocacy

Correlation between music lessons and IQ. Remember that correlations are things that happen at the same time and they do not suggest that one item causes the other. Different article from the one above (I think).

A terrific moral argument for music.

Neuroscience and anthropological justification of music education
Check out this website. It suggests the skills that students need for the 21st century.
On this page is a lot of the resources for Partnership for 21st Century, including (scroll down....."21st Century Skills Arts Map"). The arts map shows how the arts (including music) help to teach these critical skills. This page also has a lot of background stuff on the ideas behind 21st Century skills, which can help you to establish why what these people have to say is important.