Audio Patents Project From 2007 TO 2017

In the period 2007…2017 the AES Historical Committee gave space on the website for a project dealing with audio patents. The project leader was George Brock-Nannestad, and despite some progress reported in 2009, very little activity was noted, and nobody outside the narrow circle of the project ever contributed.


The following text is a revised condensation from the website of general sensible advice concerning the retrieval of patents in the pursuit of the history of technology.


It would seem relevant to present knowledge and experience concerning how to obtain access to early patents. Patenting was prolific in the US, UK, France, and Germany, and a lot of this material is retrievable. A document, “Historical Patents in EPO Databases 2009” was extracted from a bi-annual publication published electronically by the European Patent Office (EPO). This document shows the issue years of patents given access to by the EPO in 2009, and the coverage has only increased since. The selection shown mainly presents countries where dates back to 1920…1930 or older are included.


The AES Historical Committee website gives a link to patents at the German Patent and Trademark Office (DEPATIS) for world-wide retrieval of patent information. This access is not the only, nor necessarily the best way of obtaining organized information in specific audio areas, because the amount of material is overwhelming and they deliberately make access more difficult than necessary. This is because that website does not intend to compete with commercial services. However, for academic historical research this commercial consideration is not relevant, and we are free to improve the access to non-copyrighted material as we wish. To that end, Rick Chinn, Jay McKnight, and Friedrich Engel have provided running revisions of instructions on the AES HC website. The latest improvement has been that full-text versions may now be downloaded in one operation.


An alternative and in many respects more complete and sophisticated access is obtained via the European Patent Office website mentioned above. Its sister website, which is also the official registry file of all publicly available European patent applications, is termed European Patent Register (, and this has an image database that will give access to all correspondence in the various applications. The US Patent and Trade Marks Office provides a similar set of databases, and these are very useful for particular searches as well as for studying the correspondence in US applications.


The high quality of the British “Abridgements of Specifications” has been recognized by the European Patent Office, and they presently form the basis for abstracts and selected drawings for all British patents from ca. 1890 that may be searched by means of the EPO tools. The abstract texts are not 100% identical to those obtained by browsing the original printed books of abridgements, but they link to the full texts of the patents in question all the way back.


BACKGROUND: Abridgements were tools for the examination of UK patent applications before the 1977 Patents Act, because there was only examination with respect to prior UK patents. These abridgements that were prepared by the patent examiners themselves are hence extremely condensed versions of the patents in question and much better than the abstracts written by the applicants generally found in more recent US patents (and in post-1977 British patents!).

Presently the EPO may be searched for applicant and via a modern classification back to 1890, and dependent on how you define your requirements, you may have the original Abridgement text and the images that go with it or download the full text of the British patent.


The best subject matter search in an organised fashion is obtained by entering the subject terms in the Title and Abstracts field and GB in the Publication Number field. This is because volumes and volumes of Abridgements of Patents have been scanned and OCRd along with the images that were in the printed publications. The correctness of the OCR is good, which you cannot say for GooglePatents. And you get access to a pdf copy of the British patent. The date coverage is fabulous.


Text recognition software has generated raw ASCII files of description and claims that are also available on the website, but they have not been proofread as regards the early years. The Abridgements published would have been different in the various classifications that they were published in, but the European project is satisfied with only one abridgement. The time frame for this European project embraces newer and older patents.


A source with a huge added value was the “Review of acoustical patents from the Journal of the Acoustical Society of America”, a regular feature in J AES from Vol. 16, Issue 4, 1968 October until Vol. 39, Issue 11, 1991 November. Each patent was commented upon by a panel of specialists, and these comments were selectively imported from the Journal of the Acoustical Society of America in order that only those that were deemed to be of interest to the audio community, rather than the broader acoustical community, were shown.


With the initiative of the AES HC from 2016 that makes available complete historical issues of the J AES it is now possible to browse these entries. You used to need the paper copy for that.


So-called family information is very difficult to find concerning historical patents: this means patents for the same invention in several countries. The best compiled information would be found in historical company archives.


Otherwise this information can only be labouriously collated and tabulated by reading each individual patent and noting the circumstances under which the application was written. If it says “Convention Priority”, then the date and any number refers to the first application anywhere in the World. However, that number will not be the number that the patent that issues is known under in the first country of application. Again, it is necessary to labouriously collate the information from this patent, only in this case it is called “Application Number”. Working systematically, a table of patent families may be built up. Sometimes inventors’ names are made available – in the US this is compulsory.


For early US patents dealing with sound recording, a private endeavour by Patrick Feaster is very useful: his website is:

GBN 2017-11-23

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