Audience filing reveals technical details about a dependency in the A5 chip

Feb 6, 2012 09:18 GMT  ·  By

Newly-revealed details about Apple’s A5 chip inside the iPhone 4S are shedding new light on the company’s reasons not to ship Siri for iPhone 4 handsets. It appears that the reason wasn’t marketing after all. It was tech-related.

Audience, a company that licensed its latest EarSmart technology to Apple, said its partner chose to embed the solution in the A5 silicon.

This not only made it thicker, according to Linley Group analyst Linley Gwennap, but it also explained why the iPhone 4 didn’t get Siri.

"Even after accounting for the dual Cortex-A9 CPUs and the large GPU that provides the A5 with industry-leading 3D graphics performance, the remaining die area seems too large for the usual mundane housekeeping logic," Gwennap said.

"To reduce system cost and eliminate the extra package required for the Audience chip, Apple cut a deal to integrate the noise-reduction technology directly into its A5 processor, which appears in the iPhone 4S."

In a filing for an initial public offering (IPO) of stock, Audience said that the iPhone 4 used an outdated version of its technology. The one that’s built in the iPhone 4S is better, and Siri requires it to decode and interpret speech, according to Gwennap.

"This situation helps explain why Apple does not offer Siri as a software upgrade on the iPhone 4. Although the older phone includes an Audience chip, the company has since improved its technology to handle 'far-field speech,' which means holding the device at arm's length rather than directly in front of the mouth," Gwennap said.

According to Cnet, Audience also revealed in its filing that Apple signed to be a licensee of its noise-reduction intellectual property (IP) in Q4 2011.

The filing specifically said that, "Commencing in the three months ended December 31, 2011, Apple has integrated our processor IP in certain of its mobile phones. Pursuant to our agreement, this OEM [original equipment manufacturer] will pay us a royalty, on a quarterly basis, for the use of our processor IP for all mobile phones in which it is used."

Apple has been granted a third license to use the technology in a future chip (likely the A6 SoC to be used in the next iPhone and iPad), though "this OEM is not obligated to incorporate our processor IP into any of its current or future mobile devices," Audience said.