get_comment_type( int|WP_Comment $comment_ID )

function get_comment_type( $comment_ID = 0 ) {
	$comment = get_comment( $comment_ID );
	if ( '' == $comment->comment_type )
		$comment->comment_type = 'comment';

	/**
	 * Filters the returned comment type.
	 *
	 * @since WP-1.5.0
	 * @since WP-4.1.0 The `$comment_ID` and `$comment` parameters were added.
	 *
	 * @param string     $comment_type The type of comment, such as 'comment', 'pingback', or 'trackback'.
	 * @param int 	     $comment_ID   The comment ID.
	 * @param WP_Comment $comment      The comment object.
	 */
	return apply_filters( 'get_comment_type', $comment->comment_type, $comment->comment_ID, $comment );
}