| T O P I C R E V I E W |
| petty |
Posted - Jun 20 2003 : 4:07:20 PM
Just wanted to give the heads-up about an issue and see if anyone else has had similar experiences.
I was the subject in my own experiment today for testing purposes. The study is a mismatch-negativity study with auditory stimuli. I could only hear our tones in one ear although they were being sent in stereo. The sound controller display showed that they were in-fact being sent to both ears, however I could only hear them in one. Has anyone had this problem?
Possible problems from this -- a MMN shown only in one hemisphere, could be from the sounds only being sent to the contra-lateral ear...?
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| 4 L A T E S T R E P L I E S (Newest First) |
| jim.voyvodic |
Posted - Jul 03 2003 : 10:11:17 AM
If balancing the sound levels is important for your experiments you should probably do it for every subject at the beginning of your session. You could play test tones during the shimming scans, for example. Volume levels will depend on the sounds being generated or played from a file, as well as volume and balance controls in the computer, and the audio system. So the only reliable test is what the subject actually hears. In CIGAL, the "Test I/O Devices" in the Showplay menu could be used for this. It generates a tone in both ears every time the subject presses a button. You could just ask the subject to keep pressing while you adjust the sound balance controls, until the sound is loud enough and balanced. I could help create a better sound adjustment test program if there is a need.
The new headphones we received had MUCH louder sound levels, which should make it easier to get balanced sounds at any volume. Unfortunately they had to be sent back because the padding generated an imaging artifact. I expect them back with new padding anyday now.
Jim |
| garrett.rosania |
Posted - Jul 02 2003 : 1:47:27 PM
Yesterday I had a scan and the subject was unable to hear the tones well enough to continue with the experiment. The temp fix that chris administered to equalize the output from each phone seems to have lowered the volume enough that the head phones are no longer audible over the machine noise and earplugs.
chris, is there anyone around that would know when we can expect the new headphones and how did you match the volumes between the two phones? |
| petty |
Posted - Jun 25 2003 : 1:39:43 PM
I know that there are new headphone, goggles and button boxes on the way. However, i'm not sure when they will get here. I'm sure this will remedy the problem, but for now we have just decreased the sound in one of the earphones to match the sound in the softer side. |
| Zodic |
Posted - Jun 23 2003 : 1:58:26 PM
Hi,
I think I encouumter the "same" problem recently. I am performing an auditory spatial attention experiment now. And almost all my subjects claim that the "supposed-to-be-binaural" cues seems to be biased to the left ear (e.g. the sound is louder in left ear than right ear). And this is very critical for my experiment cause if the the sound of a "cue" is biased in the first place, the subjects' attention has already been pulled to one side of space "reflexively", this might insert a confound factor in our study. Besides, the overall volume for the headphone in 4T is very soft, this may raise another problem for presenting auditory stimuli in experiment in the future, if anybody else is going to do one. So I was wondering that is there anyone who can help us to figure it out or improve the quality of the headphone?? Thanks so much~
Sincerely,
Vince |
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