Why there is only image output no audio output after connect to HDMI cable

Firstly please make sure that it is buildt in Speaker type display and the HDMI cable connect to the audio & video output interface correctly.
Secondly make sure that the display adapter driver is correct, and then you need to set the audio output as the HDMI output signal.
All of the above, If this does not resolve your problem, please contact Email:vcomnet@vcom.hk to get professional advice.