Today the US Patent & Trademark Office published a pair of patent applications from Apple relating to audio inventions. The first patent was invented by acoustical engineer specialists at Apple who previously worked at JBL and Bose. The invention can be applied to iDevices that can't support high Fidelity speakers such as an iPhone, iPad, headphones over or in-ear styles. Apple's engineers invent a new approach to smaller speakers by creating a decoupled speaker membrane assembly which improves sound output.

Back in May MacRumors reported on a technical note put out by a JP Morgan analyst stating that the iPhone 8 would come with an "enhanced receiver" with "further improvements to stereo sound." Today's published patent could be describing that very improvement.

Apple's patent FIG. 1 FIG. 1 illustrates a top plan view of one embodiment of a speaker membrane assembly; FIG. 7 is an over-ear headphone cup in which the new membrane as disclosed in the patent may be implemented.

Apple's patent FIG. 6 illustrates a frequency response curve for a driver having a decoupled membrane. In particular, frequency response chart 600 includes dashed line 602 illustrating a frequency response curve for a driver experiencing a substantial drop in sound pressure at a breakup mode frequency X (e.g., a frequency from 2 kHz to 15 kHz). The solid line 604 represents the response curve of a driver having a decoupled membrane tuned to have a natural resonant frequency at the breakup mode frequency X.

In this aspect, it can be seen that due to the tuning of the membrane, there is a peak 608 (or increase) in sound pressure output at the breakup mode frequency X. In this aspect, the drop in sound pressure output at the breakup mode frequency X is now compensated by the peak 608 in sound pressure output at the breakup frequency X, and the sound output of the driver is therefore improved.

You have to be an audio engineer to appreciate the level of detail and the jargon most consumers are oblivious to. But if you're a brave soul, then check out Apple's patent application 20170195796 titled "Microspeaker with Improved High Frequency Extension." Apple filed their patent application in January 2016 which was published today by USPTO.

Loudspeaker Equalizer

Apple's second audio patent that was published today was likely an acquired patent being that the inventors don't seem to be directly linked to Apple. While this is in no way the definitive HomePod invention, it could have in fact played a role in the design of the unit. The invention is to provide an easy to use and more effective way to provide a global equalization for a driver to produce a more balanced frequency response responsive to the environment in which the loudspeaker system is placed.

Apple's description of how the HomePod works in-part matches up to what the patent covers. Apple notes: "Equipped with spatial awareness, HomePod is smart enough to sense where in the room it's playing." This is what today's patent is describing.

The computational unit #108 in Apple's patent FIG. 1 is coupled to the external microphone #106 and the internal microphone 104. The computational unit is configured to determine an equalization filter responsive to the external microphone and the internal microphone #104. The adaptive equalization filter is implemented by the DSP #110 as determined by the computational unit to produce a more balanced frequency response responsive to the environment in which the loudspeaker system is placed. The computational unit may estimate a volume velocity of the loudspeaker diaphragm by using the instantaneous pressure in the back volume measured by the internal microphone.

Apple's patent application 20170195790 was originally filed in January 2016 and published today by the U.S. Patent Office.

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