Get a user’s role by user ID (in comments)

Hi!
I’m using this function to display the author role:
https://core.trac.www.ads-software.com/attachment/ticket/5290/author-template-the_author_role.diff

function get_the_author_role() {
	global $wpdb, $wp_roles, $authordata;

	if ( !isset($wp_roles) )
		$wp_roles = new WP_Roles();

	foreach($wp_roles->role_names as $role => $Role) {
		$caps = $wpdb->prefix . 'capabilities';
		if (array_key_exists($role, $authordata->$caps))
			return $Role;
	}
}

/**
 * Echo the account role of the author of the current post in the Loop.
 * @see get_the_author_role()
 * @return null
 */
function the_author_role() {
	echo get_the_author_role();
}

(founded here)

and now, I would like to display the author role on comments (like on this wordpress support site); when using this function, it show the same role for all comments ( because it’s in reality the role of the author of the commented post).
What can I do?

Thanks