Audio doesn't sound in a few iOS devices -

i have developed app plays audio files voices recordings. when debug have no problems it, when download appstore works perfectly, friends use , haven't got problem app, few people on world have contacted me tell me app doesn't sound.

it strange because tell me sound of bell (mp3 44100hz, mono, 128kbps) plays first sounds voices (mp3 44100hz, stereo, 96kbps) don't sound. people contact me has different devices models , different versions of ios 6.

i use avaudioplayer play files , think work well.

have experienced same problem?

thank

update

this localizable.strings have

i load file this:

//  nsstring *filelang = nslocalizedstring(aitem.filename, nil); //more code ... theplayerurl = [[nsbundle mainbundle] urlforresource:filelang   withextension:@"mp3"]; //more code ... avaudioplayer *player = [[avaudioplayer alloc] initwithcontentsofurl: aitem.urlaudio error:&error]; player.delegate = self; [player preparetoplay]; 

this example of localizable.strings file keys , values, default name of key spanish version of file:

//audio names  "1_au_es" = "1_au_en"; "2_au_es" = "2_au_en"; "3_au_es" = "3_au_en"; "4_au_es" = "4_au_en"; "5_au_es" = "5_au_en"; "6_au_es" = "6_au_en"; "7_au_es" = "7_au_en"; "8_au_es" = "8_au_en"; "9_au_es" = "9_au_en"; "10_au_es" = "10_au_en"; "11_au_es" = "11_au_en"; "12_au_es" = "12_au_en"; "13_au_es" = "13_au_en"; "14_au_es" = "14_au_en"; "15_au_es" = "15_au_en"; "16_au_es" = "16_au_en"; "17_au_es" = "17_au_en"; "18_au_es" = "18_au_en"; "19_au_es" = "19_au_en"; 

have ensured vibrate button isn't flipped on? wrote translate app had users mute/put vibrate button flipped on. seems simple, i've gotten 15 emails alone, saying app had no audio.

it seems simple, solution easiest , quickest fix. vibrate mode, turns off audio, apps.

my translate app used avaudioplayer, , there nothing programmatically wrong. user error.