You will need to go to HP and download the driver. They drivers are hardware-specific unlike the video drivers due to how they integrate with motherboards, and audio cards.
Here's a bit of back history on the problem. N3V created their sound driver based on the specs given for audio drivers. The problem is there was a mistake in the spec causing this issue, which is not just Trainz-related and affects other programs that do things with the audio. Since that time, N3V has moved on to X-Audio for TRS22 and up, but unfortunately, never updated TRS19.
In the meantime, some hardware manufacturers such as Dell, Lenovo, etc., have updated their drivers, so there's hopes that HP did the same with their laptops. Good luck with this.