Binding Problem (Binding property from ObservableCollection inside a ObservableCollection)

Hi guys, I have a problem with binding. This is my model(a shorter version):

public class Talk
{
public List rooms { get; set; }
public ObservableCollection speakers { get; set; }
public string video_url { get; set; }
public Rating rating { get; set; }
}

and this is the model for Speaker(also a shorter version):

public class Speaker
{
public string name { get; set; }
public string url_facebook { get; set; }
public string url_twitter { get; set; }
public string url_linkedin { get; set; }
public string url_xing { get; set; }
public string url_google { get; set; }
}

And from my ViewModel I'm binding to my View this: "public ObservableCollection<Grouping<string, Talk>> ConferenceListGrouped", so, which means I can display in View, every property from my model. What I can't understand is, one thing which I'm trying to access and to bind is the Speaker property "name", and I don't know how to reach that point. Can someone give some advices? Or this this is not possible?