Solución : No tieneUS male voice

he utilizadoAVSpeechSynthesizer framework paraiOS7.0

AVSpeechUtterance *utt = [AVSpeechUtterance speechUtteranceWithString:@"Hello"]; 
if (isMale) //flag for male or female voice selected
{
    // need US male voice as en-US is providing only US female voice
    utt.voice = [AVSpeechSynthesisVoice voiceWithLanguage:@"en-GB"]; //UK male voice 
}
else
{
    utt.voice = [AVSpeechSynthesisVoice voiceWithLanguage:@"en-US"]; //US female voice
}

Necesito usarUS male voice en lugar demale UK voice.