Re: Auditory Steady-State Response

Chip, 

After a cursory reading of your post, I was just wondering whether you employed signal-averaging, wherein, you look at the brain responses that follow the presentation of the same auditory stimulus over and over, then average the time-locked responses over time.  The idea is that, over a large number of stimuli, the background noise of the brain’s electrical activity will fall away, and the time-locked responses to the many stimuli will gradually get more and more intense as they are averaged algebraically, until you have a clear response curve for the same repeated stimulus.  I recall from my auditory training, that pure tone thresholds could be detected with this method from the responses in the structures in the brain stem. (It was called Brain Stem Evoked Response Audiometry, or BSER for short)  Researching BSER may help you with placement of electrodes.  I hope what I’ve written isn’t too obvious or elementary.  

In any case, your work sounds really intriguing, and I’d like to find out more about it.

Eric
From: Chip Audette 
Sent: Saturday, January 31, 2015 8:29 AM
To: [email protected] 
Subject: Re: [Openeeg-list] Auditory Steady-State Response


Hi John,

Thanks for the analysis of my work vs Kim's.  I did a follow-up experiment that did exactly what you said...put one sound on one side and the other sound on the other side.  I still got nothing.  Bummer.

My experiment was using headphones instead of loudspeakers, but I've found other papers (not Kim's) where they used headphones, so I'm assuming that's not the problem.

Recently, I did a third experiment using someone else's EEG system and using a full 32-chan cap.  Of course, now we're having trouble reading the data from that system.  Assuming we get the data, we'll see if the signature shows up in that recording.

Chip


>>>>>>>>>>

Message: 5
Date: Sat, 31 Jan 2015 06:20:06 -0600
From: John Ruelas <[email protected]>
Subject: Re: [Openeeg-list] Auditory Steady-State Response
To: "Discussion of EEG hardware, software, training protocols, NFB
        theory -        for developers and users."
        <[email protected]>
Message-ID: <D0F21B02.B48B%[email protected]>
Content-Type: text/plain; charset="iso-8859-1"

Hi Chip,

In Kim?s experiment the two tones were played simultaneously, one to the
right sound field and the other to the left sound field. In your experiment,
the two tones were played separately both into the same sound field (if I
understand correctly). In Kim?s experiment, I would guess that the signal
picked up by the Cz electrode was produced more-so by the processing of the
AM tone than the actual sensory reception of that sound. The differences in
your experiments may have removed some that sensory processing.

Try using Audacity to create an audio file in ?stereo? where the left
channel plays the 37hz AM tone and and right channel plays the 43hz AM tone.

This is simply a guess at what the issue may be, assuming the experiment was
conducted correctly otherwise.

Cheers,
John



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Dive into the World of Parallel Programming. The Go Parallel Website,
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hub for all things parallel software development, from weekly thought
leadership blogs to news, videos, case studies, tutorials and more. Take a
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