Apple files patent to improve iPhone sound quality

Credit: pxhere

iPhones are generally known to have a better sound quality compared to their Android counterparts.

Apple is working towards further improving iPhone sound quality by using an adsorbent material in the back volume of its speaker.

Apple has filed a patent application with the United States Patent and Trademark Office in this regard. The application was published on June 6th, 2019.

Apple notes in its filing that, “portable consumer electronics devices, such as mobile phones, have continued to become more and more compact. As the form factor of such devices shrinks, system enclosures become smaller and the space available for speaker integration is reduced.

More particularly, the space available for a speaker back volume decreases, and along with it, low frequency acoustic performance diminishes. The effective back volume of a portable consumer electronics device may, however, be increased without increasing the actual physical size of the back volume.

More particularly, an adsorbent material may be incorporated within the back volume to lower the frequency of the natural resonance peak and thereby make bass sounds louder. The adsorbent material may reduce the spring rate of the speaker by adsorbing and desorbing air molecules as pressure fluctuates within the back volume during sound generation.

Such adsorption/desorption can increase system efficiency at lower frequencies to produce more audio power. Thus, the audio speaker may produce better sound in the same form factor, or produce equivalent sound in a smaller form factor.”

Apple further notes that, “Directly incorporating an adsorbent material within the back volume to improve acoustic performance may, however, cause negative side effects.

In particular, incorporating loose adsorbent particles directly within the back volume may create a system that is physically unbalanced and susceptible to damage as the particles shift, e.g., due to the mobile device being carried or moved by a user.

Furthermore, attempting to mitigate these effects by packaging the adsorbent particles in a secondary enclosure such as a mesh bag located in the back volume may cost precious enclosure space, as the secondary enclosure walls occupy vertical clearance in the back volume.

Thus, for adsorbent materials to be used in a speaker back volume to enhance acoustic performance within the smallest possible form factor, an audio speaker having an adsorptive insert that is physically stable and efficiently utilizes the available back volume may be needed.” 

In an embodiment of the Apple’s invention, an audio speaker includes a physically stable adsorptive insert that is located in, and occupies a substantial portion of, a speaker back volume.

The audio speaker incudes a speaker housing having a speaker port and an inner surface. A loudspeaker may be mounted in the speaker port to define the back volume between the loudspeaker and the inner surface.

The adsorptive insert that is located in the back volume includes adsorptive particles bound together to form a rigid open-pore body having an outer surface surrounding a spatial volume. The spatial volume occupied by the monolithic open-pore body may be a same order of magnitude as the back volume, e.g., the spatial volume may occupy a majority of the back volume.

Apple’s FIG. 1 shown below is a pictorial view of an electronic device in accordance with an embodiment. 

Apple’s FIG. 2 shown is a sectional view of an audio speaker having an adsorptive insert within a speaker housing in accordance with an embodiment.

This patent publication 20190174223, was initially filed on Feb 5th, 2019. This is a continuation application of co-pending U.S. patent application Ser. No. 15/198,852, filed Jun. 30, 2016.

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