DVI supports video signals only; it does not support audio. Since the DVI jack on the connected device does not output audio, the HDMI connection on the TV is not receiving any audio. Therefore, the DVI-to-HDMI cable only provides the picture to the TV screen, but the TV speakers cannot output any sound. In this case, it is also necessary to connect an audio connection from the audio output jack of the source device to the appropriate audio input jack on the TV.
NOTE: Make sure that the HDMI input on the TV is the one that offers an analog audio input. The audio input on the TV may be a red and white composite cable or a stereo headphone cable. The image below is an example of the two possible connections.