A while back, I asked the Twittersphere if they had any idea what the little button on the HTC Surround’s speaker did. For the first month or two that I owned the phone, I didn’t even realize that it was a button; I just thought it was an inset tweeter or something on the speakers themselves. Then, at one point, I accidentally pressed it and realized that I got haptic feedback.

No one on Twitter had any answers. I started searching online, and couldn’t find any information about it, either. Then, the other day, I happened to be watching a video on my phone and accidentally pressed the button again. Lo and behold, the sound quality changed. I pressed it again, and there was another change to the sound quality.

It then occurred to me that that button actually changes the speaker mode for the phone. Pressing the button will switch the phone between “No effects”, “Dolby Mobile” and “SRS Enhancement”. This magical button is located in the top left of your speaker deck when you slide it out and hold the phone in landscape mode.

Of course, if I had bothered to read the owner’s manual that came with my phone, I might have learned that a lot quicker; but where’s the fun in that?

Following is an excerpt from page 66 of the manual (warning, that is a link to a 5 meg PDF file):

You can also set a sound option when the surround speakers are open by pressing the button on the surround speakers to cycle between options. See “Slide-out surround speakers and kickstand” in the Basics chapter to see the location of the button.

If you read that portion of the manual, you will also find that there is a Windows Phone app in the HTC Hub (though, it doesn’t appear that it’s actually available in the Windows Phone Marketplace) called Sound Enhancer, that allows you to change these settings without using that button.

The sound enhancements for music are separate from the sound enhancements for video, so you can actually use two completely different settings for each.