Next, James Croft (Croft Acoustical) presents us with another masterpiece analysis of loudspeaker-related knowledge. In his Acoustic Patents column, he explores a patent awarded to Shure Acquisition Holdings, listing Brent Robert Shumard and Thomas Andrew Satrom as inventors. The title of the patent is "Audio Devices Having Low-Frequency Extension Filter" and its abstract details a filter that may increase and extend the bass frequency response of a speaker of an audio device, including ways to simulate the acoustic effects of a much larger rear cavity, and acoustic pathways, such as quarter wavelength tubes.
Having previously explored similar patents with corresponding intents, James Croft awards us with another delightful exploration of prior art, quoting some unique and bizarre inventions, but also some essential innovations that have contributed to better low-frequency architectures. As always, these are areas that have progressed tremendously with the availability of modern simulation tools, and the interesting Shure patent reflects that progress.
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