Linking directly to audio files - http

Question

I've inherited a website that contains about 100 audio files. The links to the files are relative links like this:
part 1
Back in the day those usually forced a download. Newer browsers now play the audio in browser. Except....
If the user comes to the site over https they are able to navigate the site and the html pages load, but the links to the audio files generate a 403 Forbidden error. Changing the protocol in the location http allows the mp3 to load and playback in the browser.
Why would the mp3 files be forbidden over https?
Is there a way to force the http protocol without having to make all the links absolute links? I notice the relative links "inherit" the protocol of the page they were loaded on. There isn't anything on any of these pages that need https so I wouldn't mind forcing all the parent pages to load over http....
This is a departmental site within a giant university. So I don't have access to the server, htaccess, or any of those kinds of tricks. All in browser, javascript, html solutions please.
UPDATE
I installed Firebug to view the headers and discovered that the audio plays fine in FireFox (on my mac). In Safari they load and play, but the controls don't show the progress or time, but they do play. And in Chrome they don't play at all.
I had also checked them on my PC at work and they don't play in IE9 (I know! Corporate IT, right?) or Chrome.
Here is what I get for headers in Firefox where the audio plays fine.
HTTP/1.1 200 OK
Date: Sat, 11 Apr 2015 15:39:04 GMT
Server: Apache
WWW: www3
Vary: X-Forwarded-Proto
Last-Modified: Tue, 16 Nov 2010 14:19:25 GMT
Etag: "78e935-d60ac-4952c3e68d540"
Accept-Ranges: bytes
Content-Length: 876716
Keep-Alive: timeout=5, max=100
Connection: Keep-Alive
Content-Type: audio/mpeg
GET /dept/area/language/stories/sounds/file.mp3 HTTP/1.1
Host: example.edu
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:33.0) Gecko/20100101 Firefox/33.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Referer: https://example.edu/dept/area/language/stories.html
Cookie: _ga=GA1.2.829124232.1405280613; BIGipServerWWW-HTTP=1378527424.20480.0000; _gat=1
Connection: keep-alive
And these are what I get in Chrome.
Remote Address:128.122.119.202:443
Request URL:https://example.edu/dept/area/language/stories/sounds/file.mp3
Request Method:GET
Status Code:206 Partial Content
HTTP/1.1 206 Partial Content
Date: Sat, 11 Apr 2015 15:46:12 GMT
Server: Apache
WWW: www4
Vary: X-Forwarded-Proto
Last-Modified: Tue, 16 Nov 2010 14:19:12 GMT
ETag: "78e939-158dbc-4952c3da27800"
Accept-Ranges: bytes
Content-Length: 1
Content-Range: bytes 382271-382271/1412540
Keep-Alive: timeout=5, max=100
Connection: Keep-Alive
Content-Type: audio/mpeg
GET /dept/area/language/stories/sounds/file.mp3 HTTP/1.1
Host: www.nyu.edu
Connection: keep-alive
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2272.118 Safari/537.36
DNT: 1
Referer: https://example.edu/dept/area/language/stories.html
Accept-Encoding: gzip, deflate, sdch
Accept-Language: en-US,en;q=0.8,es;q=0.6,hi;q=0.4,pt;q=0.2
Cookie: _ap_utmz=57748789.1416681263.3.1.utmccn=(direct)|utmcsr=(direct)|utmcmd=(none); _ap_utma=57748789.722895429.1387124094.1423327171.1425612794.7; __utma=57748789.194555315.1387124094.1423327171.1425612794.7; __utmz=57748789.1416681262.3.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); BIGipServerWWW-HTTP=1395304640.20480.0000; _gat=1; _ga=GA1.2.194555315.1387124094
Range: bytes=382271-382271
If-Range: "78e939-158dbc-4952c3da27800"

Answer 1

HTTP Request and Response Headers
Make sure to read about headers, mime types and content encodings.
You could try to utilise the Content-Disposition response header
An opportunity to raise a "File Download" dialogue box for a known MIME type with binary format or suggest a filename for dynamic content. Quotes are necessary with special characters.
Source: Wikipedia
Anyway your issue seems like a http header issue, could be compression as well. Take a look at your headers and whats different and troubleshoot from there. When you understood the problem, you can think of solutions.
Troubleshooting Tools
Use firebug or chrome developer tools to investigate. Fiddler Proxy to simulate different headers, since you have no access to your server.
File Permissions
Could be that SSL runs as another user or config on your server and the mp3 files have the wrong permissions or their parent directory. You need to check those, but since you have no server access you could be out of luck.
However, if SSL is not important to you just link to the files like so:
<a href="http://yourDomain.tld/folder/anotherFolder/file.mp3">
This will enforce the http protocol being used for the links. Most likely this results in the SSL chain being broken due to the mix in of http traffic into your ssl secured traffic. Therefore there's another alternative to achieve what you want:
Meta Refreshes
<meta http-equiv="refresh" content="3; URL=http://www.yourNonSSLDomain.tld/">
This will redirect to your non-SSL website where you can make sure to not mix https and http resources in your html document.