The application, published by the U.S. Patent and Trademark Office and uncovered by AppleInsider on Thursday, describes a case that could be made out of plastic, acrylic, polycarbonate, silicon or rubber. The windscreen portion of the case could be made out of a mesh, foam, or feather-like structure.
"The removable case includes an opening that aligns with a microphone port that is built into the device," Apple's application reads. "A windscreen is sealed across the opening of the case. The windscreen is designed to reduce wind noise, air blasts, vocal plosives, and other noise."
The windscreen would also double as protection for the microphone by keeping "moisture, dirt, or dust" out.
Apple's filing is also of interest because it describes the company's view on reasons for adding a case to an iPhone. The company said cases have been developed for a "variety of reasons," such as for protection when placed in a handbag, to add a method for affixing the device and aesthetic features that allow a users to "express her personality."
The invention's description of the removable case notes that the accessory could also be called a skin, bumper, or cover.
Apple has generally taken a minimalist approach to the cases it designs for its iPhone and iPad devices. In 2010, the company released a $29 Bumper case alongside the iPhone 4. After Apple began receiving complaints that the iPhone 4 was subject to signal loss when held a certain way, the iPhone maker gave away free cases to customers.
In 2011, Apple announced a magnetic Smart Cover for the iPad 2. The USPTO granted Apple a design patent for the Smart Cover in April. This year, Apple revised the Smart Cover to also protect the back of the new iPad and dubbed the new accessory the Smart Case.