Speech Intelligibility

Speech Intelligibility is fundamental to a room design, whether it′s a courtroom, hearing room, or other location that requires parties to hear the spoken word correctly.  Why is it so important? A great example to explain the importance is to read the following paragraph:

"For many listeners in a court, tribunal or commission, the proceedings will have a major impact on their lives.  The sound of speech in the courtroom should therefore be comfortable, so that listeners are able to easily recognise words without having to strain or concentrate on listening. This must be achieved under all normal operating circumstances." Stuart Herring / Redfish

The main aim in any acoustic design for these type rooms is therefore to ensure that each person in the room can clearly be heard and understood.  Any person listening must be able to understand what the person speaking is saying; in other words the speech must be comprehensible and understandable.

Each spoken word is created out of the phonetic combination of a limited set of vowel and consonant speech sound units, and it is the correct recognition of the consonant sounds that is the principle factor in speech intelligibility.  However, consonant sounds are nearly all of a transient nature ? They are very short and rapidly changing sounds, often having very little acoustic power.

If every person within a courtroom is to hear well it is obvious that the sound, particularly the high frequency consonant sounds, at each listening position must be loud enough. It sound complex and it can be complex to get right.  One of the core measurement to get it right however is meet the international standard for Speech Transmission Index (STIpa) IEC 60268-16:2011.   This standard is the most  established method for measuring speech intelligibility.

Redfish Technologies has invested time in understanding this issue, and more importantly in way to manage and create the best speech intelligibility possible for any room. We have invested in calibrated certified equipment that can test STI and Reverberation Times (RT60) to ensure any room meets the highest level of speech intelligibility.  We also work with like-minded partners who can go even further above this level of testing to "tune" a room to a level that is only possible with high level commercial audio equipment, a high level of expertise and sophisticated testing instruments.

The most important aspect of all of this type of testing is to get the architectural design of any room correct form the outset. We encourage design consultants, architectures, builders and project designers to contact us first to ensure your designs will work prior to any project starting.
Take a look below at some of our certified and calibrated testing equipment.

SMAART Audio Analyser

 Redfish Technologies has invested the SMAART software.  Our team is qualified in its use and setup.   SMAART is an audio analyser that works with a calibrated reference microphone in the room.  A dual-channel, Fast-Fourier Transform (FFT) based software platform that we use in our work as audio engineers to view the frequency content of signals or measure the response of our electrical and electro-acoustic systems. Much like medical instrumentation for doctors, this tool helps us examine our sound systems in detail and diagnose and solve problems.
As audio engineers, we use SMAART to identify tones/frequencies of interest and help us with tasks like feedback suppression and channel equalization. It also is invaluable in the process of setting up and aligning our speaker systems for the room environment.

Audio Generator & Impedance Meter

The Minirator MR-PRO provides a full set of analogue audio signals including sine wave, pink noise, white noise, delay test signal, polarity test signal, stepped sweep and continuous sine sweep. Further, a set of wave-files, useful for system optimization, is stored in the internal flash memory.

The signal balance, phantom power and impedance of the connected load are monitored. The integrated XLR cable tester simplifies trouble shooting tasks.  The generators are indispensable and proven tools for set-up, maintenance and monitoring of audio equipment of all types

Applications include.    Installed Sound, Life Safety Systems, Live Sound, Broadcast, Building Acoustics, Industrial and Aerospace, Quality Control



Acoustic and Audio Analyser

The XL2 Analyser forms the unique combination of a state-of-the-art Sound Level Meter, a comprehensive Acoustic Analyser as well as a powerful Audio Analyser. Redfish Technologies uses this in conjunction with the M4260 calibrated reference microphone.

Besides being an advanced, integrating Sound Level Meter, the XL2 measures RTA and FFT high-resolution spectra, RT60 Reverberation Time, Polarity, Delay and THD+N. Also included is the ability to test STIPA, extended acoustics functions, noise curves, cinema calibration, pass/fail analysis and remote measurement acquisition.  Data and audio is logged onto the SD card for transfer to the computer so a complete report can be complied of the test area for future reference.

Applications include.    Installed Sound, Life Safety Systems (EVAC), Noise Monitoring, Live Sound, Broadcast, Building Acoustics, Industrial and Aerospace

Acoustic Generator (STIPA Reference)

The TalkBox is an acoustic signal generator for speech intelligibility measurements in evacuation and announcement systems, as well as for level alignment of teleconference or other audio systems. It allows  the complete end-to-end evaluation of the speech intelligibility STIPA from the talker?s microphone to the listener?s ears.

The TalkBox simulates a human talker (60 dBA @ 1 meter according to IEC 60268-16) with the STIPA test signal and spoken messages. Further it provides a wide range of test signals like sine, pink noise, white noise and delay.  The TalkBox features human head-like dimensions and is based on a solid-state-generator. It replays the STIPA test signal at the precisely equalized frequency response, also ensuring best performance through the internal amplifier and the precision loudspeaker.

Dodecahedron Speaker

Self Powered Dodecahedron

The Self Powered Dodecahedron for the use of reverberation testing from within the room.  This unit provides a single sound source point to allow audio signals to be centred around the room.

Redfish uses the very first active dodecahedron speaker available on the market and is one of the most advanced and flexible systems available on the market.  Manufacture Switzerland, which is well known for quality systems and precision test instruments.

The speaker is provided in an extremely compact enclosure, with 12 extended frequency response speakers and a 650W amplifier module,  2 IN / 4 OUT DSP and a Rx module for remote control of the Dodecahedron test speaker.

Applications include.    Applications requiring a spherical sound field,  Architectural and Building Acoustics, Airborne Sound Insulation, Reverberation Time, Impact Sound Level


Contact us today to find out how Redfish Technologies can help with ensuring your organisation rooms have the best speech intelligibility possible.

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