We do audio downloads through our site securely. We are using :

session_cache_limiter('private, must-revalidate');
header("Content-Disposition: attachment; filename=\"$f_name\"");
header("Pragma: public");
//Set the content type
header('Content-type: '.$filetype);
header("Content-type: application/x-download");
header("Accept-Ranges: bytes");
header("Content-Length: $download_size");
//Read the file into the browser.
readfile( $path . $file );

The issue is that using this code does not allow users to browse links in the parent window till the download is complete. The client we are working for is requiring this functionality. Please help us resolve this as soon as possible.