While listening to music on head set: How to avoid sound playing from phone speakers when push event occurs?

I use my Android phone to listen to music at work with standard headset. Yet once an event occurs, e.g. e-mail recieved, the phone switches to standard speakers and plays the music and event sound over it, and then returns back to headset. I want all my sounds to only play over the headset. How do configure my Huawei Honor to do so?