How to get a clean Auditory Brainstem Response ?

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Alexandre
Posts: 13
Joined: Tue Jul 07, 2009 3:22 pm
Location: Montreal

How to get a clean Auditory Brainstem Response ?

Post by Alexandre »

Hello,

I have the ABR system and using it in speedmode 9 to collect ABR to click sounds. I have some trouble obtaining a clean response that could be compared to a clinical ABR.

I found this nice graph on your website
http://www.biosemi.com/abr.htm

You provide some details about how you generated this nice waveform, but I would like to know more, could you tell me what was the intensity of the click and some extra information about the recording setup that was used ? Also what are the online filters and other parameters ?

Or/and put me in touch with the person that did this recording ?

Thank you very much in advance for your help,

Regards

A.

ps : The information provided on your pages mentions (8192 sweeps), left ear (blue) has masking noise, right ear (red) has clicks at 19 Hz

Alexandre
Posts: 13
Joined: Tue Jul 07, 2009 3:22 pm
Location: Montreal

Any hint ?

Post by Alexandre »

Hello,

Does anybody use Biosemi for ABRs that could comment ?
Shall I rather email directly to support ?
Thank you

A.

Coen
Site Admin
Posts: 1124
Joined: Fri Mar 26, 2004 7:00 pm
Location: Amsterdam, Netherlands
Contact:

Post by Coen »

The filter settings used with the ABR example on our website were HP at 100 Hz and LP at 3 kHz. The special ABR electrodes that you are using have the same default filter settings. The example on our website was recorded with standard EX flat electrodes, the special ABR electrodes should in theory allow a lower noise level.

Are your problems due to a high noise level (grey traces), or due to a low response amplitude (blue/red traces) ?

Best regards, Coen (BioSemi)

Alexandre
Posts: 13
Joined: Tue Jul 07, 2009 3:22 pm
Location: Montreal

Post by Alexandre »

Thank you for your reply,

I use the special ABR electrodes in speedmode 9.
I am not using the online average, I do perform the averaging offline in matlab. I get a dstinguishable wave 5 but the other waves are quite messy. Indeed my problem has to do with noise.

My main question was about the intensity of the stimulus you used in dB and the transducers used ?

If I understand correctly, when in speedmode 9, the aquired signal is already filtered between 100-3000, without any option to open the filter more ? Are you using earlobe or mastoids ?

I will try replicating your settings, using 9000 trials and see what I get. I'd be happy if you can put me in touch with other scientific groups that use your product for research ABRs.

Best,

A.

Hal
Posts: 3
Joined: Wed Sep 14, 2011 10:02 pm
Location: Halifax

ABR quality

Post by Hal »

Could it be the stimulation rate? The early waves of the ABR are difficult to obtain with higher rates (e.g., 50 Hz), but should be easy at lower rates (e.g., 10 Hz).

I am unwrapping a new system here with the ABR receiver but haven't tried it yet. Fingers crossed.

Have you had any success since your last post?

Alexandre
Posts: 13
Joined: Tue Jul 07, 2009 3:22 pm
Location: Montreal

Post by Alexandre »

Hi Hal,

Thanks for your comment.
Indeed, using a low stimulation rate and enough repetitions, I was able to get a clean response with the 5 waves present. Best

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