Dear fMRI experts,
I recently tested the adaptive noise-canceling headphone in our fMRI scanner, and I found that without wearing earplugs, the noise of the scanner can still be quite high. When the scanner stops, I do hear pulses of sound still generated by the headphone at the interval of the TR, which I assume is supposed to counteract the noise of EPI sequence.
For those of you who have used such noise-canceling headphones, I wonder whether the need to still wear earplugs is expected for such devices?
Our distributor of the system didn’t seem to know any other way to verify the device is functioning well. I wonder if anyone knows anyway to verify that such system has reached the level of effect that it is supposed to reach?
Thank you very much!
Ahoi hoi @lcnature,
thank you very much for posting this interesting question.
Before we actually dive into this important topic, could you maybe share a bit more information regarding your setup so that folks here can provide respective pointers and help? For example: model and make of headphones, data acquisition protocol, stimuli, etc. ?
Thank you very much! Here is the link to the product: http://www.optoacoustics.com/medical/optoactive/features
I am using multi-echo EPI with multi-band enabled. Stimuli are either movie or music.
Hi @PeerHerholz just wondering if you have any insights. Thanks!
Ahoi hoi @lcnature,
oh my, I’m so sorry for my delayed response.
Did you find any new insights already?
Unfortunately, I never worked with this setup, but it looks very interesting and promising. The problem you’re facing is an auditory neuroscience “classic” (lucky vision researchers, eh?) and it’s very hard to get some standards/works for all solution. This is based on the individualized hearing experience of each and every participant, which in turn depends on a multitude of factors: hearing loss, hearing habits, etc. . Additionally, your scanner, paradigm and setup all influence things.
It appears strange that the distributor couldn’t tell how to verify the system, did you contact the manufacturer as well? From their website it seems that there should be a device that monitors sound exposure and noise levels. Did you check that?
In all the experiments I did, I always provided hearing protection (earplugs) along with the (over ear) headphones. For the stuff I’m doing (lots of music processing, audiometry, hearing thresholds and natural sounds/naturalistic experiments) this combination appeared to be working well for most participants.
I usually do some test runs to check if the stimuli can be improved and let participants set their own sound level (spoiler: most of them, I think all actually, used the highest possible setting).
Wrt your setup: as you know, multi-echo with multi-band will create a lot of what is called “Acoustic Scanner Noise” that will mask quite a bit of your stimuli. Movies and/or music are complex and versatile in nature and some features will be more effected than others (e.g. pitch). If you haven’t done so already, make sure to check Jonathan Peelle’s great paper on that here, as well as those that cited it. There’s also this great article from Sam Norman-Haignere and Josh McDermott: here.
(Unfortunately none of them is active here).
Looking forward to discussing this further.
HTH, cheers Peer
We are currently using the same ANC headphones for an auditory fMRI study and we haven’t had much success with reducing the noise of our MB EPI sequences. Although the monitor shows a reduction of >20dB at the two main frequency peaks, the subjective noise experienced by the participant is not reduced much, if at all! We are starting to wonder whether the noise that isn’t removed by passive means is primarily transmitted through bone conduction and therefore isn’t affected much by ANC…
Hi @mriscientist our experiment is delayed. When I put myself in the scanner, I could barely heat the movie we play. I think the original design might expect us to use the plastic holder and air cushion to further reduce noise transmission through the coil but that’s just not feasible given the size of our 32 channel head coil. The headphone might also expect good seal around the ears but again without putting the cushion the headphone is not tight. I did find the movie was more audible if I push the headphone with my hands. So perhaps next time we try we will put other padding to push in the headphone. My RA said it worked well for him, and I suspect it was because his head is bigger than mine:)