How to Run: cerebPacedVot

How to run cerebPacedVot (2022)


Special running circumstances

This experiment is part of the cerebellar battery run in 2022-2023. For controls and patients, it is in the FIRST session.

In this battery, participants come in for multiple sessions and do multiple experiments in a row. As such, this is a bare bones document on how to run the experiment. Procedures for consent, hearing screening, awareness surveys, general equipment set up, and payment are not included in this document. See the documents below for how these procedures are implemented in this multi-study session: 

  1. Protocol for cerebellar battery: controls
  2. For patients

What's special about this experiment

This is an unusual experiment in that it is not an altered auditory feedback study. In this study, participants will first see a word that they will use in that trial. They will then hear a series of clicks through the headphones. The clicks will start relatively slow but get faster through the trial. There will be a countdown for the first 3 clicks, so they can get used to the pace and prepare. Then the word will appear on the screen. At that point, they will repeat the word in time with the clicks. 


This experiment is conducted using PTB so there is not the usual duplicated experimenter display. Instructions to the experimenter are displayed in Matlab's command window. 

Hardware prep

Special hardware requirements: 

  • Open-back headphones, or headphones that do not excessively muffle normal auditory feedback.  
  • A Scarlett with two input ports. Both Scarlett 2i2 and Scarlett Solo will support this experiment. On a Scarlett 2i2, both input ports are dual XRL+1/4". On a Scarlett Solo, the first input is XLR and the second is 1/4". 
  • 1/4" to 1/4" (6.3 mm) male to male connector cord. This experiment will work with a single stereo cord or using one side of dual input/output cords. If you are using a dual-dual cord, be sure to connect the same side on each end (red to red or black to black). 

Before the experiment begins: 

  1. Change out the headphones in the experiment room for open-back headphones. These headphones have a mesh on the back of the earpieces rather than solid plastic. 
  2. Connect the fourth output port of the headphone amp to the second input port of the Focusrite using the 1/4" to 1/4" cord. (There will be one labeled "cerebPacedVot" near Burnham.) 
  3. Turn the gain of the fourth output port to 50%. Turn the gain of the second input port to 50%. Note: This is NOT the volume that participants will hear the metronome at. That volume will be controlled by the second headphone amp (the one that goes to the participant)

To test the connection between the headphone amp and the Focusrite, in the Matlab command window, type: 


The metronome channel should run up to amplitude of between +/- 0.1 to 0.2 or so. If you get any warnings about either channel, check that the gain is set to 50% on both the headphone and the Focusrite ports. If your figure shows clipping in the line labeled channel 2, turn down the gain on the headphone side if possible. If not, turn the gain down on the Focusrite side if possible. Then run the test again. 

Setup diagram: 

Diagram for hardware setup

Experiment prelude 

Start the experiment by typing in run_cerebPacedVot_expt in the command window and hitting enter.

Hardware check

You will first run through equipment checks and will have to answer a few questions about the equipment setup: 

  1. Is the participant wearing OPEN BACK headphones? (answer should be yes)
  2. Is there a 1/4" to 1/4" cord connecting the output amp back to the Focusrite second input? (answer should be yes) 

Then, tell the participant: "You will hear some clicks shortly. This is just a check to make sure our equipment is working properly." 

After the automatic check is done, check the output plotted in the figure. You should be able to clearly see the clicks in the signal, with a max amplitude of about +/- 0.2. If either channel is not receiving input, Matlab will inform you which channel is wrong. Double check that everything is connected and powered on and redo the hardware check. 

Volume check

After the hardware checks, you will do a volume check. Tell the participant: "We'll start with a volume check to make sure the metronome is at a good loudness. You'll want to be able to comfortably hear this while you are talking." 

  • If you are in the same room as the participant or can see them while the clicks are ongoing
    • tell them: "I'm going to play the metronome that you'll hear for the rest of the study. As it is playing, tell me if you want the volume lower or higher by pointing with your finger and I'll adjust it as we go. If it is okay, give me a thumbs up." 
  • If you are in a separate room and can't see them:
    • Err on the side of caution and turn down the gain on their headphone output before starting. 
    • Wait for the entire stimulus to play through. 
    • After the stimulus is done, ask the participant: "Is the volume of the metronome okay, or would you like it to be adjusted?" 

The command window will then ask you if you would like to repeat the volume check. If you have to adjust the volume at all, press 1. If the volume was good, press 0. Note: The PTB screen is listening for this input, not Matlab, so you do not have to actually type in the command window. 

Matlab will then prompt you to press the spacebar when you are ready to repeat. Repeat as many times as is necessary. 


This experiment will then move onto a practice phase so that participants can get used to the task, and so that you as the experimenter can see if the pacing clicks need to be slowed down. 

Tell the participant: "We'll start with a practice section so you can get used to the task."  The remainder of the instructions will be on the screen. 

When they finish the practice, the experiment will ask you if it seems like they need to go slower. This is a provision for the cerebellar patients, who often have a hard time repeating one syllable at speed. We do expect that people will have difficulty towards the end of the clicks, when they are speaking the fastest. However, if people consistently had difficulty near the beginning of the task (i.e., in within the first 5 clicks that they were speaking for), you can type in "slower" and the practice will repeat with a slightly slower pace. 

If it seems that the participant runs out of breath too early, encourage them to try again, but this time take a deep breath before they start speaking

If the participant did not have difficulty, ask them: "Are you comfortable with the task, or would you like to practice again?" If they express hesitation that the clicks are too hard at the end, you can tell them that that is okay, and they should just try their best. You can repeat practice as many times as they like. 

Main Phase

"We'll now move onto the main experiment, which will take about 10 minutes. You will be doing the same task you just practiced for the rest of the experiment. Do you have any questions before we start?"

If no questions, "Whenever you're ready, you may begin."

Things to keep an eye on:

  • Monitor the amplitude level. You may need to adjust the microphone gain if the participant starts talking too loudly or too quietly.
  • Make sure the participant is not running out of breath midway through. 

This is a self-paced experiment, in that participants have to press the spacebar to start the next trial. So if participants need a little break, they can always stop at a trial. There is no additional pause function. 

After the experiment

"Great job! You are finished with the speaking portion of the experiment. I will be in to take off your headphones." 

After the participant leaves

  1. Copy participant data from local drive to smng server (see PURPLE section below these numbered points)
  2. If you completed a hearing screening, copy the results from the local drive to the smng server
    1. There are folders on the desktop called "audiometer results - local" and "audiometer results - server". Drag the participant's audiometer results file from the "local" to the "server" folder.
  3. Fill out Lab Notebook, located in \\wcs-cifs\wc\smng\admin\
  4. Fill out check register or the extra credit register, located in \\wcs-cifs\wc\smng\admin\
  5. Double-check that the Experiment Checklist is complete
  6. Return the Experiment Running Sheet and the Checklist to the lab manager

The data will be saved in C:\Users\Public\Documents\experiments\cerebPacedVot\acousticData\. Copy the participant's folder into: \\wcs-cifs\wc\smng\experiments\cerebPacedVot\acousticData 

If Matlab crashes during the experiment

[[ Gotta figure out what to do for this experiment. RK]] 


Keywordshow to run, cerebellar, ptb, paced, cerebPaced, cerebPacedVOT, vot   Doc ID120774
OwnerRobin K.GroupSMNG Lab Manual
Created2022-08-18 12:04:43Updated2023-02-10 12:27:11
SitesSpeech Motor Neuroscience Group
Feedback  0   0