One line map: var voices = ((await ttsInstance.getVoices) as List<dynamic>).where((voice) => voice['locale'] == 'en-US').map((voice) => voice['name']).toList();
var voices = ((await ttsInstance.getVoices) as List<dynamic>).where((voice) => voice['locale'] == 'en-US').map((voice) => voice['name']).toList();