What is the Virtualizer sound effect in music players and how does it work?

Question

I use PlayerPro to play music on my smartphone.

In PlayerPro there are "Sound Effects", which are similar to the DSP manager. One of the sound effects is the Virtualizer.

When I enable the Virtualizer, even at 1%, it really changes the way the music feels. The audio becomes more echoey, and it sounds to me like I'm closer to the music. It gives me a live concert feeling.

When I played with the Virtualizer level I noticed there's a major difference between 0% and 1%. The difference from 1% to 100% is also noticeable, but it's not even close to the drastic difference when the Virtualizer is disabled compared to when it's enabled.

What does the Virtualizer do? What is it for, really?
How does the Virtualizer work?
How does this sound effect simulate a live concert sound (at least that's what it feels like to me)?

Answer 1

What's really the purpose of the Virtualizer?

I am unable to understand why you've asked this. Virtualizers make music cool. Using it, users can tweak music listening experience. It enables you to experience live concert in a car, for example.

The difference from 1% to 100% is also noticeable but it's not even close to the difference when the Virtualizer is disabled compared to when it's enabled.

Its because your speakers aren't that powerful. Just connect your device to a high-end speaker/headphone & feel the changes.

How does the Virtualizer work?
How does this sound effect simulate a live show music (atleast that's what it feels like to me)?

Demystify yourself when you are at a live concert. Your ear drums interface the air with special vibrations (sound waves) which gives you that feeling. At home, air hitting your ear drum doesn't have that specialty of live show. What virtualizer does is that it vibrates the air (hitting ear drum) in special way. In short, virtualizers just alter the sound in a special way.

How these algorithms work in background is out of scope of this site. To understand them, you need a strong background in Computer Science and Acoustics (Physics dealing with mechanical waves). Its thing of research. I can bet that even developers of PlayerPro haven't invested time & money to develop it. They have just used openly available libraries developed by research organizations, universities etc.

Answer 2

In the description of PlayerPro in Google Play this was mentioned:

STEREO WIDENING effect (virtualizer)

and a quick search on Wikipedia about what Stereo Widening is:

Stereo widening

Widening of the stereo image can be achieved by manipulating the relationship of the center signal M and the side signal S: M = (L + R)/2; S = (L - R)/2. A positive part of the side signal S is now fed into the left channel and a part with its phase inverted to the right channel. Some boomboxes feature such a process.

Another way of looking at this same effect, without extrapolating a center and side signal from the left and right signals, is to simply add the left signal, slightly attenuated and phase inverted, into the right channel and vice-versa. Taking this a step further, a small delay (20-100ms) can be added to the inverted signal before mixing it back in to the original for output, adding a slight reverberation to the effect.

Answer 3

The virutalizer widens the stereo of your speakers) headphones, by emitting what you could call an "Anti-Sound" (this is obviously not a correct name, but it explains what I want to say) to cancel out the left stereo sound in the right stereo speaker. That way it sounds like the stereo is further apart.