Siri Is iPhone 4S-Only Today, But Where Will It Be Tomorrow?

Apple is launching the iPhone 4S this week with the recently unveiled integration of Siri, a voice activated “assistant.” Siri accepts voice input and can perform a range of actions on your iPhone, including looking up information, adding calendar events, and even composing short texts and e-mails.

Right now Siri is limited to the iPhone 4S. Presumably much of the reason for that limitation is that Siri requires a lot of computing power to work. Siri co-founder Norman Winarsky told 9to5 Mac that the Siri app, originally released in early 2010, required a number of workarounds and optimizations to work well on the then-current iPhone 3GS’s 600MHz processor. Even with the significant processing boost gained from the iPhone 4S’s dual-core A5 processor, however, Apple is still calling the tech a “beta” nearly two years after its first public release.

Apple has set pretty high expectations for Siri, and it likely didn’t want to hamper it with compromises to get it to work on older hardware. After all, the company never quite lived down the mocking it received for early iterations of the handwriting recognition in its Newton MessagePad. Though later versions worked quite well (and the technology was eventually integrated into Mac OS X as Inkwell), its reputation for completely misinterpreting handwritten words never died.

However, the iPad 2 already has the relatively high powered A5 processor built in, so it’s easy to assumeit would be the next iOS device to get a Siri upgrade. Recent evidence buried in iOS 5 suggests Apple is already working on an A5-powered Apple TV, perhaps bringing support for 1080p video to the tiny set-top box. With an A5 processor, you could potentially tell your Apple TV to play the next episode of The Venture Bros instead of fumbling with its simplistic remote. Unfortunately, the iPod touch was passed over for an A5 upgrade for this holiday season, so it may be as much as a year before the iPod touch could potentially take advantage of Siri.

While these sound like easy things to pull off, the fact is that that these devices may not get Siri at all—at least not in the short term. Besides a relatively beefy processor to power Siri’s natural language interpreter, it also relies on speech-to-text recognition technology from Nuance. This works by encoding and sending an audio file to Nuance’s servers, which return the interpreted text to the iPhone. Without a constant data connection, Siri doesn’t work, period. iPhones are rarely without data connections, but the same can’t be said for WiFi-only iPads and iPod touches. Apple will still need to find a way to work the feature into these devices in a way that doesn’t frustrate users when it isn’t available after leaving the range of a convenient WiFi signal.

Another limitation may also be a device’s included microphone. The iPhone 4S has, like its iPhone 4 predecessor, a secondary microphone used to filter background noise. Those with experience using Nuance’s Dragon speech-to-text products for Windows or Mac OS X are undoubtedly familiar with the need for a good quality headset to get the best results—and even then accuracy isn’t 100 percent. Given this, we believe that the relatively low quality microphones in the iPad and iPod touch again may not give the best results, and could possibly prevent these devices from using Siri in the near future.