Nintendo of America filed for a patent to cover voice to text chat conversion. Patent application 20060025214 was filed in July 29, 2004 with the United States Patent and Trademark Office (USPTO), but has only appeared on the agency's website recently. Nintendo believes that voice to text conversion could enhance online games by altering color and font size of text depending on the tone and amplitude of the speaker's voice.
Online games have had voice chat for a while, but Nintendo claims in the patent application that this may not work too well and says, "If a 12 year old boy is playing the role of a 40 year old warrior, voice chat can spoil or detract from the game play experience since the warrior ends up having the voice of a 12 year old." The solution is to let you speak normally and have the software convert the speech into text. Of course, mere text cannot convey emotion so Nintendo wants to change the format of the speech in response to changes in your voice.
Font size can change along with the amplitude or loudness of your voice. So if you scream into the microphone the text would appear quite big on the screen. In addition, Nintendo wants to have the color change in response to the tone of your voice.