I need to combine the following sentence pair. First, reduce the second sentence to a participial or n absolute phrase, changing the form of the verb if necessary. Then, insert the phrase into the first sentence. Be sure to place a participial phrase next to the noun or pronoun it modifiers.

1. Some virtual reality systems include a small speaker for each user. These systems use sound to enhance the illusion of the simulated world

Give it a try, and I'll check your work.

Read through these if you need help:
http://www.chompchomp.com/terms/participlephrase.htm
and
http://www.chompchomp.com/terms/absolutephrase.htm

To combine the sentences and reduce the second sentence to a participial phrase, we first need to identify the noun or pronoun that the phrase will modify. In this case, the phrase should modify "virtual reality systems." Now, we can rephrase the second sentence.

2. Changing the form of the verb if necessary, the systems use sound to enhance the illusion of the simulated world.

Now we can insert the reduced phrase into the first sentence:

Combined sentence: Some virtual reality systems, using sound to enhance the illusion of the simulated world, include a small speaker for each user.

In this combined sentence, the participial phrase "using sound to enhance the illusion of the simulated world" is placed next to the noun it modifies, "virtual reality systems."