When learning Tai chi movements and for daily practice, relaxing/zen music of your choice is calming. It will help you to concentrate on your personal journey. After you put the individual movements all together, music is a good guide for timing and immersing yourself in the experience. There are some examples here, to get you started, but as usual, YouTube videos come with commercials, so be prepared to hear at least one pitch for a product. As you get serious about your practice, invest a few dollars and purchase a CD, mp3, or streaming music service for uninterrupted, proper music. Keep pets from getting underfoot during your practice, and most of all, if you need to block out a TV playing in another room (or any noise), wear headphones.
Example of daily practice music.
The song "Imagine" is about three minutes long. It's good for those people early in their training (Yang Style) to put all the movements of the 24 form together, but then you will need to slow it WAY down and move onto other music.
In general, an instrumental is preferable to vocals when it comes to your practice, but "Hallelujah" comes in at about 4 and half minutes (depending on the version) and will help you adjust your movements to a slower pace.
Once you go from 3 minutes to 4 1/2 minutes, it's time to slow the form down even more until you reach a 6 minute completion time. You can do this by using general tai chi practice music or finding a slow instrumental piece that comes in at 6 minutes. At six minutes you will be able to incorporate every principle for the maximum benefit.
This tai chi music below or something similar is great for slowing down your movements and hitting the 6 minute 24 Short Form mark. Enjoy your practice! Don't forget to breathe properly with each move, regardless of pace!
Peace
Exercise with soothing music works for me.