ExpSuite is a program that compiles the implementation of psychoacoustic experiments. ExpSuite is the name of a framework that is used as a basis for an application. It can be enlarged with customized and experiment-dependent methods (applications). The framework consists of a user-interface (experimentator-and-subject interface), signal processing modules (off-line and in real-time), and input-output modules.
The user-interface is implemented in Visual Basic.NET and benefits from the "Rapid Application Development" environment, which develops experiments quickly. To compensate for the sometimes slow processing performance of VB, the stimulation signals can be processed in a vector-oriented way using a direct link to MATLAB. Because of the direct link to MATLAB, numerous MATLAB intern functions are available to the ExpSuite applications.
The interface accessible to the people administering the tests contains several templates that can be chosen for a specific experiment. Either the keyboard, mouse, joypad, or joystick can be chosen as the input device. The user interface is designed for dual screen equipment, and allows a permanent surveillance of the experiment status on the same computer. Additionally, the transmission of the current experiment status to another computer is possible via a network connection.The framework supports two types of stimulation:
- the standard acoustic stimulation using an audio interface for experiments with normal or impaired hearing subjects, and
- the direct electric stimulation of cochlear implants for experiments with cochlear implant listeners.
In the acoustic mode, the signals are passed to Pure-Data (pd). In pd, which is a real-time signal processing environment, the data can be post-processed and presented to a multi-channel sound interface. The post-processing units allow not only simple mixing and output of the signals, but also complex filtering, signal generation in real-time, and the recording of sounds simultaneously with playback. In pd, the ASIO drivers are used, allowing a multi-channel signal presentation and acquisition with low latencies. Additionally, there is a visualization module (graphic environment module, GEM) that can be used for visualization and visual experimentation in real-time. The link between the VB and pd is based on a network connection and allows the outsourcing of computationally intensive pd processes to other computers, keeping the system as scalable as possible. In the case of an electric stimulation, the research interface boxes (RIB) are used to stimulate cochlear implants made by MED-EL bilaterally. Products from other manufacturers could easily be included if required, currently the implementation of NIC (Cochlear) is in progress. The interaural timing accuracy is below 2 µs.
The security of the data is very important; all experiment data are administrated in a separate directory. Thus, the stimulation files and the experiment parameters are available during and even after the end of the experiment. Additionally, all experiment parameters are immediately backed up in a log file, before the beginning of the experiment. During the experiment, after each test person's response, all parameters of the currents' stimuli and the corresponding responses are inserted in the log file and all files are closed. So, all actual responses are available even in the case of a potential system crash. The parameters and the evaluation data are administrated in reader-friendly format (comma separated variables, CSV files). Then, the results can be automatically read by many applications like MS Excel, OpenOffice or MATLAB.
Approximately 15 different applications using ExpSuite have been developed at the Acoustics Research Institute so far. The tools are use for HRTF measurement, localisation studies, detecting loudness function curves, ITD/ILD discrimination, speech tests and several others.
The software is under EUPL license and can be downloaded from http://sourceforge.net/projects/expsuite/.