Desktop Video, Display and Touch

Hi,

Is there a way to get audio output from this monitor (HP 27F 4k)? For perspective, I am currently using this as a 2nd display via the display port attached to a thunderbolt dock attached to my macbook. I've been trying to  find other uses for the other ports on the monitor and I was wondering if there is a way to connect a speaker at the monitor. I was hoping to connect  a spare chromecast to the free hdmi ports but I am unsure how to output audio from it. My dock has free usb 3.1 and one free type c port. So far I am thinking of testing several solutions but I wanted to ask if other have done the same and see if they have other methods.

Currently the way I get audio is via the laptop I have connected to the dock which connects me to this monitor. The rechargeable speaker I have has USB, Aux inputs and is rechargeable via Micro USB. I hope to connect an external speaker (without the laptop) to this monitor only with the monitor, speaker (rechargeable), and dock (can be plugged in). 

Methods I've possibly thought of  (Chromecast will be connected via hdmi to monitor):

1. Speaker (powered by rechargeable battery) connected via HDMI to USB Cable to monitor

2. Speaker (powered by rechargeable battery) connected via HDMI Male to VGA Female Adapter with 3.5 Jack to monitor

3. Speaker (powered by rechargeable battery)  connected to Dock which connects via DP to monitor.

Will any of these work? I am not an IT guy so I am just basing what I wanted to try on whether they have the same port or not. 

Thanks!