Apple has been granted a patent (20200152165) for “acoustic filler including acoustically active beads and expandable filler” that hints at even better speakers on iPhones, iPads, and Macs.
Loudspeakers include a back volume and a membrane or diaphragm that oscillates and emits sound when driven by an electromagnetic transducer. A variety of different forces act on the membrane while it is being moved, distorting its intended acceleration by the electromagnet and thus distorting the sound wave it emits.
Apple says that reducing these additional membrane forces leads to improved sound quality. However, in hand-held devices such as cell phones, increasing the size of the back volume is possible only to a minor degree because these devices should be kept conveniently small. Apple’s solution:”acoustically active beads” made of absorptive materials.
Here’s the summary of the invention: “Aspects are disclosed of a filler for occupying a volume. The filler includes an expandable filler positioned in the volume so that it occupies a percentage of the volume. The expandable filler can permanently expand from a first dimension to a second dimension upon the application of an expansion trigger.
“The filler also includes an acoustic filler made up of a plurality of acoustically active beads positioned with the expandable filler in the volume so that the acoustic filler can adsorb gas flowing into the volume. Other embodiments are disclosed and claimed.”
