PHP json_encode在开头添加了双引号

Question

json_encode在开头添加双引号。非常感谢任何帮助

$response_array = array("popularity_score" => $popularity_score, "popularity_rating" => $popularity_rating);
$response = json_encode($response_array);
echo $response;

实际结果：

"{"popularity_score":13,"popularity_rating":50}

预期结果：

{"popularity_score":13,"popularity_rating":50}