NTi Audio AG

- Acoustic Signal Generator


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 performing 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. A variety of supplied or user-defined test signals may be precisely output for different alignment applications.


NTi Audio TalkBox includes a high-precision broadband loudspeaker. Perfect flatness of ±1 dB over the relevant frequency range and highest quality requirements are guaranteed by an individual equalization and calibration using advanced FIR filtering and DSP technology. The radiation characteristic complies with ITU-T P.51 in wide ranges.

The IEC 60268-16 standard specifies a sound pressure level for a speaker simulator of 60 dBA in 1 meter distance. The TalkBox output levels are calibrated to comply with this standard. To avoid operating failures the TalkBox has no volume control.

The human voice tends to be raised in level in emergency situations. In order to cope with this so called Lombard effect, all STIPA related signals are additionally offered at an increased level of 70 dBA at 1 meter.

Using the balanced line out, the TalkBox operates as a signal generator. Sampling frequency deviations - a dangerous trap when using portable CD players for STIPA measurements - are completely eliminated. Any external signal can be connected to the system using the balanced line input. The applied signal is transparently looped to the line output and processed in the internal DSP in real-time to appear equalized at the speaker.

The TalkBox also generates additional wave forms: White noise, pink noise, sine wave, reference speech signals and the delay time measurement chirp. Custom designed signals may be loaded onto the CF Card and are seamlessly looped.


Typically the NTi Audio TalkBox is positioned on a conventional mic stand in front of the talker's microphone; exactly at the position of the actual talking person during the announcements. The TalkBox features a mic stand mount on the bottom plate.

For measuring speech intelligibility in large buildings the remote mute functionality of the TalkBox is of great help. Any external switching device may be connected to the mute input, allowing e.g. a cell phone controlled ON/OFF functionality. Thus the STIPA test signal might be muted between measurements.

The TalkBox supports a power supply range 10 - 18 VDC. An external power supply for worldwide operation is included. Alternatively the optional battery pack might be used.


NTi Audio TalkBox
Acoustic Generator

NTi Audio #: 600 000 085

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