KEMAR - rejuvenated

KEMAR is introduced and is the first, commercially available head and torso simulator for acoustic measurements. KEMAR is the abbreviation of Knowles Electronics Manikin for Acoustic Research. Mahlon D. Burkhard is leading the development in close corporation with his colleagues from Industrial Research Products, Inc., Knowles Electronics and foresighted colleagues from audiology institutions and the industry. They develop KEMAR to fulfill the growing demand for realistic tests of BTE/ITE hearing aids.

KEMAR enables unprecedented and repeatable, simulated in-situ measurements with its anthropometric shape and molded rubber pinnae. This, combined with well-defined ear-canal extensions and the new Zwislocki coupler, quickly creates new methods and standards. The size is based on the average of about 5000 males and females from the US Air Force.

Two standard pinnae sizes accommodate for a variety of simulations and best-fit options. Combined with the steel ear-canal extensions this makes KEMAR a versatile research and development tool for all electro-acoustic devices where the scientist easily can modify the shapes and sizes of essential components.

Ear-mould simulators are made for BTE instruments.

KEMAR is the only head and torso simulator, with a changeable ear-to-shoulder ratio simulating both male and female median values.

Eventually applications spread from hearing aid test to test of headsets, earphones, hearing protectors and communication devices due to the realistic and repeatable coupling to the pinnae and the extended frequency range caused by the new coupler design. ANSI 3.36 and IEC 60959 standardized with numerous related measurement standards using KEMAR as the preferred acoustic manikin.

G.R.A.S.’ first introduction to KEMAR is made when Knowles is looking for suitable pressure microphones for the Zwislocki coupler. Later, G.R.A.S. supplies mounting kits and 711 couplers for retrofitting this type of standardized ear simulator on existing and new models.

Two solid ear-canal extensions are available; The standardized ø7.5 mm type and a VA-specified ø9.8 – 7.5 mm tapered type with integrated O-ring for open-ear fitting.

Later, variants are made according to customer requests for fitting new designs.

The amount of accessible measurement data, reports and projects based on KEMAR is enormous and KEMAR even has his own book edited by Mahlon Burkhard and distributed by G.R.A.S. on request.

In 2005 G.R.A.S. acquires KEMAR from Knowles and improves it by adding new functionality and features. To fit any type of analyzer input, KEMAR can now be equipped with G.R.A.S. externally- and pre-polarized IEC 60711 Ear Simulators.

KEMAR can also be mounted with ½" or ¼" pressure measurement microphones, making it the obvious choice for sound quality applications and binaural recording of e.g. music.

The calibration procedure is simplified, so the pistonphone signal can be applied from the outside by removing the pinna. To improve access and connection abilities, the base of KEMAR is modified to contain standard instrumentation terminals. The former coupling cable between ear simulator and preamplifier is substituted by the G.R.A.S. short ¼" preamplifiers for measurement microphones.

To comply with the increasing request from the telecom industry the portfolio is expanded with soft pinnae. KEMAR now offers simulation with both 55 and 35 Shore-00 pinnae. As a natural result KEMAR is given a voice – a mouth simulator – to enable diagnostics of the transmission path of all communication devices.

The demand for using KEMAR for testing communication devices increases and a very flexible handset positioning system for acoustically correct measurements of mobile telephones and smartphones is introduced. The system allows for both ITU-T recommended methods; distance and pressure relative to the ear reference point. The increased demand for quality earphones in the telecom market soon after leads to the development of an earphone positioning system, making KEMAR the only head and torso simulator with an adjustable finger.

A new baby ear simulator with baby properties is being tested by the industry. Longer, rubber-lined ear-canals adapted from the new ANSI standard for testing hearing-protectors have been developed. A minimum-metal model of KEMAR is available for testing hearing aids with radio link. The list of features and accessories for KEMAR is long and will grow in the future. We will continue to listen to our users’ ideas and requests and develop new functionality needed for KEMAR.

KEMAR turned 40. And being the father of all head and torso simulators, KEMAR has many friends and family members all over the world. All of whom has stopped by or sent greetings – of how they met and what tests were performed. Pictures and greetings have been gathered in the KEMAR Family Book.

At G.R.A.S., we are proud to house and continuously improve the first and most used head and torso simulator for acoustic research. And that is why we celebrate KEMAR’s anniversary with a "40 years and still the same – but different"...

Along with the anniversary came a new application for KEMAR. The acoustic testing of SCBA masks (Self-Contained Breathing Apparatus), typically used by firefighters and smoke-diver units.

Because of the anthropometric shape and integrated mouth simulator, KEMAR was chosen as the most realistic and best suited head and torso simulator for the standard.

Another, and maybe more colorful initiative, is the possibility of having KEMAR in other colors on request. In the role of educational tool and conserver of children’s hearing, an orange KEMAR has been traveling in Germany to help visualize the balance between noise dose and volume when listening to MP3-players.

Having celebrated 40 years’ anniversary, KEMAR has had a facelift – but remains the same in size and shape.

The new KEMAR with its improved construction is more robust. Head angle indication allows for repeatable measurements, and it is easy to access the inside of the head. The mounting is improved and now allows for more tripod options.

We will continue to listen to our users’ ideas and requests and develop new functionality needed for KEMAR.