Problem with accents and special characters [duplicate]

I'm doing an app that consumes the information of a php and I have a problem with the accents and special characters. The code works perfectly but when I get the information returned from the php in json the characters and accents are returned like this \ u00a0

I would appreciate a help, Thank you very much

client.get(url, new AsyncHttpResponseHandler(){
        @Override
        public void onSuccess(int statusCode, Header[] headers, byte[] responseBody) {
            if (statusCode == 200) {
                ArrayList<Video> arraydatos = new ArrayList<Video>();
                final Controladora controladora = new Controladora();
                arraydatos = controladora.obtDatosJSON(new String(responseBody));

                arraydatosVideos = new AdapterDatos(actividad, arraydatos, context);
                ListView listaVideos = (ListView) findViewById(R.id.home_videos);
                if (listaVideos != null){
                    listaVideos.setAdapter(arraydatosVideos);
                    ProgressBar progressBar_videos = (ProgressBar) findViewById(R.id.progressBar_home);
                    progressBar_videos.setVisibility(View.INVISIBLE);
                }
            }
        }
        @Override
        public void onFailure(int statusCode, Header[] headers, byte[] responseBody, Throwable error) {
        }
    });


public class Controladora {

//OBTENER ARREGLO DEL JSON
public ArrayList<Video> obtDatosJSON(String response){
    ArrayList<Video> arraydatos = new ArrayList<Video>();
    try {
        JSONArray jsonArray = new JSONArray(response);
        Video video;
        for (int i = 0; i < jsonArray.length(); i++){
            video = new Video(jsonArray.getJSONObject(i).getString("id_post"), jsonArray.getJSONObject(i).getString("nombre"), jsonArray.getJSONObject(i).getString("link_img"), jsonArray.getJSONObject(i).getString("link_video"), jsonArray.getJSONObject(i).getString("link_audio"), jsonArray.getJSONObject(i).getString("link_karaoke"), "");
            arraydatos.add(video);
        }

    }catch (Exception e){
        e.printStackTrace();
    }
    return arraydatos;
    }
}

PHP

<?php 
header("Access-Control-Allow-Origin: *");
define('WP_USE_THEMES', false);
if (file_exists("../../../../wp-blog-header.php"))
    require_once("../../../../wp-blog-header.php");

wp_reset_postdata();
wp_reset_query();
$ultimos_videos = array(
    'post_type' => array('videos-musicales','versiones'),
    'posts_per_page'  => '-1',
);
query_posts($ultimos_videos);
$videos_musicales = array();
if ( have_posts() ) : while ( have_posts() ) : the_post();
    $id_video = "";
    $enlace_video = "";
    if(get_field('enlace_video') != ""){
        $enlace_video = get_field('enlace_video');
        $id_video = explode("/embed/", $enlace_video);
    }
    else if(get_field('enlace_de_audio') != ""){
        $enlace_video = get_field('enlace_de_audio');
        $id_video = explode("/embed/", $enlace_video);
    }
    else if(get_field('karaoke') != ""){
        $enlace_video = get_field('karaoke');
        $id_video = explode("/embed/", $enlace_video);
    }


    $resumen = get_the_excerpt();
    array_push($videos_musicales, array('id_post'=>get_the_ID(), 'nombre'=>get_the_title(), 'link_img'=>'https://img.youtube.com/vi/'.$id_video[1].'/0.jpg', 'link_video'=>get_field('enlace_video'), 'link_audio'=>get_field('enlace_de_audio'), 'link_karaoke'=>get_field('karaoke'), 'resumen'=>$resumen));

endwhile; endif;

header("Content-Type: application/json",true);
echo json_encode($videos_musicales);
?>