Helping to picture sound measurements

For most of us, a plot is what keeps us reading a detective story until the end but there is another more technical meaning to the word which is well known to all those who work in areas related to sound and hearing.

picturing sound measurement
This graph which pictures the level of sound (Db) against frequency (Hz) has a standardized aspect ratio.

It is a concise table of information detailing sound visually, a graph with two axes, involving the use of different variables, such as decibels (dB) which measure the sound level, for instance. A sound level plot must be as accurate as possible, as it is a document that can help engineers and technicians in various sound-related industries to measure the performance of microphones, loudspeakers or even ear-pods. Plots are therefore produced using specific aspects ratios which are standardized by the IEC. An aspect ratio is an option for graphics and related functions that specifies the ratio of height to width for a plot.


New standard for the digital age


A new edition of IEC 60263 brings the specifications for these aspect ratios and plots up to date. “The previous standard was issued in 1982 and the context has changed a lot since then. In those days, plots were produced on standard-size rolls of perforated paper with a fixed aspect ratio. Nowadays we live in a largely paperless society and graphs representing sound measurements have moved to the computer screen or mobile phone. These graphs can be enlarged for the display screen and can be stretched out or compressed down making them inaccurate and difficult to interpret. It was really time to update the standard and adapt it to the digital world,” explains Christopher J. Struck, who leads the working group which prepared the publication inside Technical Committee 29. TC 29 publishes standards relating to instruments and methods of measurement in the field of electroacoustics.
“TC 29 is truly a B to B technical committee. We are there to enable other industries to manufacture and test their products to the right specifications whether telecoms, test instrumentation or consumer electronics. Members of other TCs within the IEC are also our customers, for instance IEC TC 100, which develops audiovisual standards. We liaise with TC 100 experts and they reference our standards,” Struck says.


A tool for other technical committees


The scope of the new edition covers electronic files, scientific publications, graphs in other standards as well as screen displays in programs and apps. “IEC 60263 is a reference document, similar to the IEC terminology standards. It is a fundamental publication that all other IEC Standards can reference,” he adds.
Struck is also a member of one of the TC 29 working groups on measurement microphones, hearing aids, ear simulators and modular instrumentation. He is equally an active member of ISO TC 43 which standardizes methods of measuring acoustical phenomena. “It is important to avoid silos by working with ISO and other IEC TCs. It enables us to avoid reinventing the wheel every time we develop new publications,” Struck admits.
The processes which enable us to perceive sound are very complex. Communicating information about sound and acoustical measurements should be as accurate as possible. Consistent use of standardized methods avoids misrepresentation and minimizes errors. And that is where the work of Christopher J. Struck and his fellow experts makes a difference.