The ARI lab consists of five testing and measurement stations:

  • GREEN and BLUE (ISF Grün, ISF Blau): Two sound-booths (IAC-1202A) are used for audio recording and psychoacoustic testing performed with headphones. Each of the booths is controlled from outside by a computer. Two bidirectional audio channels with sampling rates up to 192 kHz are available. The GREEN chamber is further equipped with a 64-channel EEG system (actiCHamp, Brain Products).
  • RED (ISF Rot): A visually-separated corner can be used for experiments with cochlear implant listeners. A computer controls the experimental procedure using a bilateral, direct-electric stimulation.
  • YELLOW (ISF Gelb): A Semi-Anechoic Room, with a size of 6 x 6 x 3 m, can be used for acoustic tests and measurements in a nearly-free field. As many as 24 bidirectional audio channels, virtual environments generated by a head mounted display, and audio and video surveillance are available for projects like HRTF measurement, localization tests or acoustic holography.
  • PURPLE (ISF Lila): A semi-anechoic loudspeaker array studio with 91 loudspeakers and 2 subwoofers on a size of 3 x 3 m. The system can be controlled from outside in the control room, using a multichannel audio setup with 4 amplifiers and a computer.

The rooms are not only used for measurements and experiments, but also for speech recordings, speaker identification and survey reports.

During the breaks in experiments, the subjects can use an internet terminal or relax on a couch in the lounge while sipping hot coffee...



Our EEG system (actiCHamp, Brain Products) consists of 64 active scalp electrodes, several passive electrodes to be used for electrooculography (EOG), and a StimTrak unit allowing to record audio signals along with the EEG signals. For auditory stimulus presentation, we use insert earphones (ER-2; Etymotic Research) minimizing electric noise induction and able to provide a large bandwidth. 

A semi-anechoic room (6.2m × 5.5m × 2.96m) is available for acoustic measurements. Also psychoacoustic experiments like sound-localization experiments can be performed.

The room is equipped with:

  • a 22-loudspeaker array for HRTF measurement;
  • 64-microphone array for various recording approaches (beam forming, near-field holography);
  • a virtual-environment setup for tests with subjects in a virtual visual and acoustic environment controlled with a head tracker in real time.
  • equiment for speech recordings for speaker identicication


DSCN0612 Vertical circular array of 22 loudspeakers generates acoustic signals from almost every direction. The listener is placed on a computer controlled swivel chair. DSCN0614

The loudspeaker array is mounted in a semi-anechoic room (3 x 3 m). It consists of 91 loudspeakers, arranged in a spherical order, and 2 subwoofers. This high number of loudspeakers enables many possible demonstration, for instance:

  • Present sound sources from any given directions by controlling each loudspeakers separately. One possible method is by using VBAP (Vector Base Amplitude Panning).
    Example: Ambient situation like birds tweeting around the listener, rain is dropping on a virtual roof above the listeners head, thunderstorm is slowly coming over the sky....
  • Present moving sound sources.
    Example: A fly is flying around the listener.
  • Demonstrate the listener how directional hearing can be important for everyday's life ("Cocktail Party Effect").
    Example: Some listeners are talking from the same direction. The listener is not able to understand a full sentence from any of them. Once they start moving to different positions it will be much easier to focus on one of them separately, and to understand the spoken sentence.
  • Present different types of rooms and their corresponding properties: Since the loudspeaker array studio is semi-anechoic the room does not add any reverbing effect. This allows to artificially filter the sound signal by adding the early reflections (mirror sources) and diffuse reverb (FDN) effect of any given room.
    Example: A guitar is being played without any reverberations. After half the track some room effect is added and the listener has the impression of suddenly being in small reverbing room.
  • Unusual positions: The listener can be virtually positioned in any situation by placing sound sources around the listening positions.
    Example: Enjoying a classical concert from the conductor's view.