How Could This Patent Possibly be Granted in the Face of Public Domain Prior Art?

Question

In reference to the patent: US9247339

This patent appears to have been granted without proper due-diligence having been undertaken to review the prior art. For well over 50 years now every conceivable arrangement comprising of a plurality of essentially identical drivers mounted together on a common baffle have been marketed by numerous companies. In fact, A plurality of speaker drivers configured in the form of a line array was first proposed and published by acoustical pioneer Harry Olson.[5] in 1957.

Since that time some of the biggest names in audio have employed the exact same concept. One well-known example for home use would be the Bose 901 direct/reflecting loudspeaker that employed 8 identical drivers mounted to a rearward-facing baffle (away from the listener) and a 9th driver of the same type mounted to a forward-facing baffle (towards the listener). Furthermore, Bose marketed a reverse-configuration model for use in Public Address applications wherein the enclosure was rotated 180 degrees such that the 8-driver array was facing forward and the 9th (now rearward facing) driver being eliminated altogether.

Moving forward in time, a number of companies have marketed large-format line arrays for use in large venues or outdoor festivals. In fact, several manufacturers have even developed spreadsheets or custom programs for users to design their own arrays. Examples include L-Acoustics SOUNDVISION,[14] Adamson Shooter,[15] Electro-Voice LAPS (Line Array Prediction Software),[16] D&B Audiotechnik ArrayCalc, and JBL Vertec Line Array Calculator.[17] Renkus Heinz, etc. Then finally, the number of products targeted for home use in the high-end audio market that employ the exact same concepts and principles are in numbers so high as to be almost without measure.

In all of the above examples, the same underlying principles apply as those claimed be the inventor in this patent. Basically, at low frequencies the output of the individual drivers sum to yield a greater total sound pressure level at any point distant from the array, along with an increase in total acoustic power output as commonly quantified in Acoustical Watts. Then as the operational frequency is increased, being of low mass the individual drivers are free to operate independently so as to reproduce these higher frequencies without the mass-limited attenuation that a single driver of the same total cone area as that of the sum of the individual drivers would otherwise suffer from.

A fairly comprehensive review of the matter can be found by searching "line array" at Wikipedia.

As can easily bee seen in the above link, the methods and practices claimed in this patent are clearly Public Domain and have been so for many decades. In light of these facts it appears that the patent is essentially "bogus" and without even the slightest merit, such that it would never stand if challenged in Patent Court. That said, we repeat our original question: Would the US Patent Office please explain how this patent could possibly be granted in the face of a preponderance of Public Domain Prior Art?

Answer 1

As always, what a patent protects is described in the claims. In this case the first claim is as follows.

1. A speaker comprising: a transducer configured to reproduce a sound generated by a moving and sound-generating portion of a musical instrument, the transducer comprising a moving element, wherein the moving element is limited in mass to approximate the mass of the moving and sound-generating portion of the musical instrument.

As you can see, this claim has nothing to do with arrays of speaker elements. It is trying to protect the idea of using a transducer with moving mass approximating the mass of the sound generating portion of a musical instrument. The body of the patent claims that in conventional speakers the moving mass of the transducers is more like 10 times the mass of the sound-generation portion of a musical instrument (such as a string). I don't know if that is true, and I'm not sure how they know a priori what instrument is being played in the music.

The other independent claims are claim 11:

11. A transducer for use in a loudspeaker, the transducer being intended for use in reproducing sound frequencies over a selected frequency range, the transducer comprising: a moving element, wherein the moving element is limited in mass to approximate the mass of a moving and sound-generating portion of a musical instrument having a fundamental frequency within the selected frequency range.

and claim 16:

16. A speaker comprising: an array of transducers, each of the transducers comprising a moving element, wherein the moving element of each transducer is limited in mass to approximate the mass of a moving and sound-generating portion of a musical instrument that each transducer is intended and adapted to reproduce.

Claim 11 is similar to 1 in that it is about the transducer mass and claim 16 mentions using an array of transducers where the transducers have low mass approximating the mass sound-generating portion of a musical instrument.

So you see, the patent isn't trying to claim any and all arrangements of speaker driver elements, but is really about their claimed "low-mass" transducers. Of course there have been low mass transducers in the past. I'm thinking of electrostatic transducers in particular. How they differentiate with respect to those I don't know. I will agree I find the patent questionable, but it got granted.

Some Google searching leads me to believe that TektonDesign is the patent holder. Here is their homepage. Their speakers look pretty conventional but they are claiming a "patented design". My guess is the patent is more for marketing purposes than an effort to force other companies to pay royalties.