public function paginateAudio ($offset = 0, $count = 20)
    {
        $json = $this->paginate(MediaType::AUDIO, $offset, $count);
        $resultSet = [];
        
        foreach ($json->item as $item) {
            $resultSet = new Paginated\Audio($item->media_id, $item->update_time);
        }

        return new Paginated\AudioResultSet($resultSet, $json->total_count, $offset);
    }