
An important feature for this edition, Mike Klasco and Nora Wong discuss Earphones and Headphones—Change Is Here to Stay. The article provides an update on the latest trends in the different market segments, from the more esoteric proposals to the more popular categories and growing trends, including sports. Klasco provides details of technology updates on drivers and all the materials and components for headphones and earphones. As he writes, "There is no shortage of innovations in the pipeline and at least for headphones and earphones, “change is here to stay.”
This edition also features a complete and updated 2018 directory of the leading OEM/ODM headphone and earphone factories. Valuable references validated by Nora Wong - who has recently visited most of these vendors. As she explains, "Headphones are a natural product line extension for speaker brands and many of us are finding this product type added to our to-do lists."
In this month's Acoustic Patents column, James Croft (Croft Acoustical) reviews a very curious patent from inventors Ramez Nachman (Seattle, WA), and Mohammed Aftab Alam (San Jose, CA), on behalf of Amazon Technologies, Inc. (Reno, NV) for a Smart Bass Reflex Loudspeaker. The patent, filed in 2013, was finally awarded in April 2017 and, as Croft comments, it clearly must be something they are looking at using on one of the Echo smart speaker systems. Basically, the patent discusses a new technique to tune a port of a loudspeaker, in this case multiple ports that will be open or selectively closed, in function of an analysis of the frequencies of the signal being played. The patent details the port selection vs. frequency range but doesn't provide any extra consideration for the consequences on the changes the use of different tuning ports might have on the drivers response, which indicates there must be much more to this approach than simply this intriguing patent. Croft also discusses all the multiple attempts and patents that tried to address tuning ports in one way or another. Fun reading!
And because there's a never-ending supply of new drivers reaching the market every month, Vance Dickason puts three different drivers to his Test Bench procedure. First is a new driver, the T34A-4 tweeter, from a new German company BlieSMA. The second is the 25-2234SD, which is a new high-

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