Knowledge Base

Problem

Users want to trigger sounds of different frequencies as conditioned stimuli during fear conditioning experiments. The EthoVision-compatible fear conditioning boxes (e.g., matching condition fear boxes) only support a fixed single-frequency TTL signal and cannot natively emit variable-frequency sounds through EthoVision alone.

Details

EthoVision XT communicates with external hardware via TTL pulses through the USB I/O box. However, EthoVision's TTL output is a simple high/low digital signal and cannot directly encode frequency information for a tone generator. When using third-party sound generators (e.g., VanBi or similar), the sound generator must be configured independently to produce the desired tone/frequency, then triggered by the TTL pulse from EthoVision's I/O box when the trial control rule fires. This requires connecting the Noldus I/O box TTL output port to the trigger/sound port on the fear conditioning box and pre-configuring the sound generator software with the desired frequency and intensity before trial start. A two-system approach (EthoVision controlling timing via TTL; third-party software controlling frequency) is required for multi-frequency protocols.

Solution

**Option 1 – Using third-party sound generator software (e.g., VanBi):**
1. In the third-party software (e.g., VanBi), pre-configure the sound generator with the desired frequency and intensity for each trial type before starting acquisition.
2. Connect the Noldus USB I/O box TTL output port (e.g., TTL1) to the sound trigger input port on the fear conditioning box using an appropriate cable (typically RJ45 to BNC or similar adapter).
3. In EthoVision Trial Control, create a rule that sends a HIGH TTL output signal on the configured I/O box port at the time you want the tone to play.
4. When EthoVision fires the TTL HIGH signal, the pre-configured sound generator receives the trigger and plays the tone at the programmed frequency.
5. To use different frequencies across trials, update the frequency setting in the third-party software between trials before each acquisition.

**Option 2 – Using the VanBi I/O box in parallel:**
1. Connect the VanBi I/O box TTL1 port to the sound port on the fear conditioning box.
2. Use VanBi's experimental control program to manage tone delivery independently of EthoVision.
3. Synchronize timing between EthoVision and VanBi using a shared TTL trigger or timestamp reference.

**Note:** EthoVision XT cannot directly program sound frequencies through its TTL output — it can only trigger an external device. Always pre-set the frequency and intensity in the sound generator software before the trial begins.