Akulap module for measuring speech intelligibility (STI/RASTI/STIPA) according to DIN 60268-16
Speech intelligibility is the key to human communication. For emergency warning systems, telecommunications systems, announcement systems (eg in train stations) or general rooms for speech presentation (training rooms), poor speech intelligibility not only reduces their function but is also safety-critical.
Applications
Speech intelligibility (STI) is mainly used in two areas:
- Electroacoustic emergency warning systems in accordance with IEC 60849. Many public buildings have announcement systems that can be used to inform people about the situation in an emergency. e.g. "Please leave the hall via exit E". Legally defined minimum requirements for speech intelligibility are defined here.
- Room acoustics : In recent years it has become increasingly clear that the classic parameters of room acoustics (RT60) do not adequately describe the properties of rooms with high requirements for speech communication. Speech intelligibility is also a priority for open-plan offices ( ISO3382-3 ).
Measuring method
Two measurement methods are possible for STI.
- The classic, direct method uses modulated noise and measures the modulation loss directly. However, this method is very time-consuming for all octave bands and all modulation frequencies. In recent years, however, the STI-PA method has proven itself, which only uses a fraction of the possible combinations. However, with this method, the measurement time can be limited to around 20s. The measurement setup is very simple, so that no great training effort is necessary.
- The second - indirect - method is based on the room impulse response. Using mathematical methods, speech intelligibility can be calculated from the impulse response. The room impulse response is often measured anyway as part of room acoustics investigations. In this case, determining speech intelligibility does not require any additional effort, but is included in the normal evaluation. In particular, the full STI value with all bands and modulation frequencies can be determined directly. However, the measurement method is more complex and not possible for all ELA systems to be measured, but at the same time the entire room acoustics are measured, so that the results are much more meaningful.
The direct method (STI-PA) is mainly used for emergency warning systems. The indirect method is required for open-plan offices (ISO3382-3).
Electroacoustic emergency warning systems according to IEC 60849
In many countries there are legal minimum requirements for speech intelligibility for electro-acoustic emergency warning systems. For new public buildings, speech intelligibility must be documented by measurements. In most cases, the IEC 60849 or ISO 7240-16 standard must be taken into account.
Electroacoustic emergency warning systems support the quick and efficient evacuation of buildings and are therefore being used more and more frequently. Such systems are therefore of great importance for the safety of buildings and high demands are therefore placed on the operational reliability of such systems. The DIN/EN 60849 or VDE 0828 standard for electroacoustic emergency warning systems defines the performance requirements for these systems so that the unrestricted availability of the system is guaranteed in an emergency. This standard applies to sound amplification and sound distribution systems that are used in emergency situations to prompt people who are in an area inside or outside a building to evacuate this area quickly and in an orderly manner.
Such systems are used in public areas where there are people who are not familiar with the escape routes, e.g.:
Shopping centers/sales shops, office buildings, schools, hotels/restaurants, multi-purpose buildings, banks, administrative buildings, manufacturing halls, train stations, sports facilities, cinemas
An important feature of such systems is speech intelligibility. It must be ensured that announcements can be understood by all persons concerned in an emergency.
According to the DIN 60849 / VDE 0828 standard, the intelligibility on the Common Intelligibility Scale (CIS) must be greater than or equal to 0.7. This corresponds to an STI (Speech Transmission Index) of 0.5.
Setup for measuring speech intelligibility for the direct method
The measurement setup is very simple. The test signal, which consists of special modulated noise, is fed through a test loudspeaker via the emergency system's microphone. The signal is recorded and analyzed at various points using a measurement microphone. The measurement takes about 15 seconds per measurement point.
Characteristics
- Meets IEC 60268-16 ED5 STI, STIPA, RASTI (ED2+3)
- It is very easy to use. Perform your first STIPA measurement within 2 minutes.
- Measurement via modulated noise (direct method) and room impulse response (indirect method)
- Background noise is taken into account via octave levels or directly as a .wav file. No subsequent calculation using a spreadsheet program is required. “Auditory masking” conforms to IEC 60268-16 ED 3.0 (2003) and ED 4/5 and can be switched off optionally.
- The modulation indices are displayed for each band
- Octave analyzer compliant with IEC 1260 Class 0
- Speech level measurement in accordance with IEC 60268-16 Annex J.2
- Easy export of data
