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Acoustics play an essential role in sound transmission, even in the digital age. Recording conditions and a microphone’s properties have a considerable impact on the quality of digital audio signals. And the properties of loudspeakers or headphones as well as the acoustics at the point of reproduction also affect fidelity of reproduction and our auditory perception.

IRT supplies various services in the fields of room acoustics, architectural acoustics, auralisation, loudspeakers, and micro- phones. In addition, we conduct acoustic testing and advise our clients on technical equipment for Outside Broadcast vehicles.

Acoustic services

Do you plan a studio control room or an OB van? Do you need support in optimizing the accoustics in open-plan offices or in video conference rooms, or are acoustical measurements to be performed?  IRT stands out due to its longstanding experience. We have profound expertise in room and building acoustics, auralization of virtual studios, as well as in loudspeakers, headphones and microphones.

IRT offers...
… custom-tailored services in several areas of the acoustics. With its unique and renowned simulation software AUVIS (AUralisation of VIrtual Studios) IRT has a tool at hand with which rooms can precisely be made audible before even building them. Several products which are manufacturered and marketed by partner companies under IRT’s licence underline the competence of IRT in the matter of acoustics.

We address...
…broadcasters, studio operators, producers, architects, studio device manufacturers and manufacturers of loudspeakers, headphones and microphones.

Our services & licence products

  • Expert consulting in room and building acoustics regarding the avoidance of acoustical weak spots in radio and television production rooms
  • Room acoustical simulations with our simulation software AUVIS with which we can auralise rooms based on your building plans before realizing the room or building
  • Acoustics consulting and measurements for the construction of broadcasting vans
  • Consulting for the efficient elimination of background noise
  • Preparation of a catalogue of measures for improving the acoustical working conditions in open-plan offices
  • Consulting with respect to the improvement of the speech quality transmitted from video conferencing rooms
  • Acoustical measurements – acoustic insulation, reverberation time, noise level, etc.
  • Measurements  and calculations of sound absorbers, for example for product optimization
  • Performance  of electroacoustic measurements, support in developments
  • Measurements of the room directivity dependent transmission properties of loudspeakers and microphones
  • Conducting seminars and workshops


With AUVIS we developed unique and professional room acoustics simulation software which we use at IRT for the planning of studios and control rooms on behalf of our customers. In addition to the reverberation time, further important acoustic properties can be calculated and optimized before building a room.

IRT licence products

With the KEM microphone (cardioid plane microphone) IRT has developed an entirely new type of microphone with disc-shaped directional characteristics – comparable to a line of loudspeakers – that, for example, offers advantages when miking speakers, or recording choirs. The KEM is manufactured and marketed under IRT’s licence by Microtech Gefell GmbH. The KEM is in successfull operation at the speaker's desk of the plenary hall in the Bundestag in Berlin.

With the SAGA products, IRT has developed a series of 19" equipment cabinets with special sound absorbing characteristics that particularly consider the spectrum of the noise and the mechanisms of human noise perception. The SAGA product line is manufactured and marketed under IRT’s licence by SAGA maxi GmbH. 

Acoustics in open-plan offices

In open-plan offices, there are often large windows and smooth walls. Both factors cause long reverberation times, which consequently boost the noise levels in full offices and make it very difficult to communicate. Studies have shown that such noise pollution dramatically hampers employee performance. It is therefore worthwhile for companies to invest in proper workplace acoustics.

IRT’s specialists forge acoustic improvements for open-plan offices. Thanks to simulation software developed by IRT, the efficacy of individual measures can be calculated in advance and rendered audible – before any decisions need to be made! It is possible, for example, to listen via headphones to the anticipated impact of various partition walls or specialised wall linings. This approach offers a distinct benefit: resources are invested only in those measures which will considerably enhance workplace acoustics.

Room and building acoustics

The acoustic properties of broadcast production studios should be precisely customised to the processes which take place there.

Acoustic weak points and unnecessarily complex designs ought to be avoided. IRT’s specialists work closely with clients to ensure appropriate room/architectural acoustics.

IRT has remarkable specialised expertise not only in sound/image production studios which satisfy demanding acoustic requirements (DIN 15996), but also regarding sound insulation in buildings (DIN 4109).

Main aspects

  • Advising and planning of room/architectural acoustics (from cutting rooms to complete broadcasting structures)
  • Definition of acoustic requirements such as impact sound insulation, airborne sound insulation, reverberation time, and background-noise limit curves
  • Acceptance-test measurements

IRT’s clients benefit from our decades of experience as well as the utilisation of cutting-edge computational and simulation software. IRT possesses high-quality measurement equipment for the fields of room/architectural acoustics and sound measurement technology.

Technical solutions for eliminating background noise

Unwanted background noise can be nerve-wracking during the production of radio and TV programmes. First the vent whirrs, then the monitor chirps! Permanent noise should not exceed certain limits in rooms meant for the recording or processing of sound. So that loud equipment can be operated in such rooms without annoying background noise, IRT has created a series of soundproof housings and quietised equipment cabinets.

We measure the background-noise transmission of a wide variety of devices such as flatscreens, cameras, projectors, and digital video recorders before proceeding to help you minimise any acoustic interference.

Acoustics in outdoor broadcasting vans

Producing in the field for radio and TV would be impossible without Outside Broadcast (OB) vehicles.

A good programme can only be produced, however, if the technical conditions in an OB vehicle facilitate optimum work. In order to constitute a viable setting for the work of sound engineers, OB vehicles must feature proper acoustics.

IRT aids radio and TV broadcasters with the invitation of tenders, and advises on acoustic matters in order to achieve necessary values (e.g. interior sound level, sound insulation). We also provide acoustic measurements for the acceptance testing of OB vehicles.

Reference projects fpr OB vehicles: BR, DLR, RBB, NDR, ZDF, SWR, MDR, HR, WDR.

Acoustical measurement technology of loudspeakers and microphones

IRT determines the directivity patterns of loudspeakers and microphones by means of specialised, computer-aided measurement equipment: a rack (quadrant) with 19 measurement microphones, a changeover switch, and a rotary table. The rotary table turns a loudspeaker in five-degree increments in the horizontal plane and the transfer function is measured at the 19 microphone capsules, respectively.

Individual transfer-function measurements are first collected by means of the MLS (Maximum Length Sequence) measuring method and in the form of absolute values and phase values before being stored in a database. 2,049 transfer functions and 2,049 frequency control points (i.e. 4.2 million amplitude values and 4.2 million phase values) are stored for each loudspeaker. Several hours are required to measure one loudspeaker. The automatic measuring system thus generates a data record totalling approximately 33 MB per loudspeaker. And the technique can be slightly modified for microphones, e.g. artificial heads.

Assessment of Measurement Data

Thanks to extensive data records, our specialists can combine and balance transfer functions to obtain certain sensitivity levels, various directivity indices, or polar curves for given frequency resolutions.

Visualisation of 3-D Directivity Patterns

Measurement data can be depicted especially well via a three-dimensional portrayal of directivity patterns: a single image is provided for a certain frequency band or a video sequence for several frequency bands. The measurement data can be used to calculate angular-dependent level values, which are then portrayed as a spatial grid. The relative level differences can be illustrated by gradations of colour. This coloured grid can, for example, then be visually studied from various spatial perspectives.

For a certain spatial perspective, it is possible to successively portray – as in a film – the spatial envelopes for ascending third-octave centre frequencies (e.g. from 100 Hz to 20 Hz). And the images are accompanied by the corresponding third-octave noise.



Electro acoustical measurements and developments

You want to set up new loudspeakers in a studio, have developed the prototype for a new microphone, or require special data for a piece of equipment which are not specified in the manufacturer's data sheet? IRT can assist you in these cases and many others by performing measurements to define sensitivity levels and directivity indices, impulse responses, directivity patterns, non-linear distortion, or the background noise of electroacoustic transducers.

On the basis of our readings, we can then provide precise answers to your questions and suggestions for enhancements, if necessary. IRT specialists can help you realise your ideas and develop new microphones or loudspeaker systems. We also gladly assist you with the optimisation of acoustic accessories such as microphone windshields.

IRT has an outstanding spectrum of devices at its disposal as well as all the necessary measuring facilities (e.g. anechoic chamber, reverberation chamber).

Reference Project: KEM Microphone

IRT developed KEM, a cardioid microphone which is truly innovational and features an omnidirectional directivity pattern comparable to that of a loudspeaker line. By carefully coordinating the interconnection of individual microphones along a common axis, a configuration can be created which offers advantageous angular distribution of acoustic sensitivity for a number of applications (e.g. the positioning of microphones on people for broadcast purposes or for music/theatre performances).

IRT’s KEM even enjoys great success in Germany’s Bundestag – at the speaker’s lectern on the floor of Berlin’s Reichstag.

Acoustical simulation

With the help of specialised simulation software, IRT experts can precisely calculate acoustic requirements for broadcast production studios. This makes it possible, for example, to determine the sensitivity level of a specified control loudspeaker at a control room’s stipulated monitoring point. If the outcome does not satisfy the requirements within a tolerance range, then the sensitivity level can be optimised in the model via targeted measures, e.g. by varying the loudspeaker’s position, the solid geometry, or the wall/ceiling absorption. Once all room-acoustic requirements have been met, the computational model’s room concept is realised in conjunction with the architects and companies involved.

An additional advantage of a room-acoustic simulation lies in the option of calculating the impulse responses of different monitoring points in the model, which in turn makes the simulated room virtually audible. In other words, the computational model makes it possible to hear what a certain recording would sound like in a room before it has even been built! This technique of rendering sound is referred to as auralisation.

Such room-acoustic simulations have proven to be cost-effective in practice. Any additional initial expenditures during the planning phase are outweighed by the fact that only those construction measures which are required to satisfy acoustic requirements are actually executed.

Reference Projects

  • BR Control Studio 1
  • RBB Control Studio

Additional acoustic services

Advanced Training Courses
Specialised background expertise in acoustics is essential during the construction or remodelling of production studios. Such expertise precludes acoustic weak points and increases a project’s cost-effectiveness. To share such knowledge with others, IRT specialists offer a one-day advanced training course: Room/Architectural Acoustics for Architects, Civil Engineers, Studio Planners, and Project Managers. Courses are held on request and, if the customer so desires, on site.

Room-in-Room Systems
It can be particularly challenging at trade shows to attract people’s undivided attention to your products or ideas.

IRT has developed a presentation concept which is tailored to this and similarly demanding situations. Appropriate room acoustics can be created simply by setting up a self-contained “room-in-room” system.

References: IFA, Tonmeistertagung, Audio Engineering Society Convention

Acoustic Measurements
As specialists for research and development, we at IRT conduct an extensive array of acoustic measurements such as the following: absorption and reflection coefficients, impedances, noise emission, release behaviour, structure-borne sound, sound insulation of very differing components, and the electrical data of electroacoustic transducers.

Our measuring facilities (e.g. anechoic chamber, reverberation chamber) provide us with remarkably precise readings.

Calculation of Sound Absorbers
During the planning phase of construction or renovation, there are often questions about the impact which, for example, new wall linings or microperforated materials could have on room acoustics. In order to forecast which measures would truly improve acoustics, IRT has developed a programme which can simulate the impact of individual acoustic modifications. This programme also allows us to determine the absorption coefficient of hybrid materials.

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