Any recommendation for MR-compatible insert earphones?

[julienbesle <julienbesle@xxxxxxxxx>]

Hello list

We're looking to replace our MR-compatible acoustic stimulation system 
and are looking for some advice .
We currently use a Nordic Neurolab electrostatic Earphone system. It is 
working fine and in particular the frequency trasnfer function is flat 
enough (not as flat as advertised though). However a major drawback for 
us is that the inserts themselves are made of hard material, are quite 
bulky and stick out of the subject's ears. We use a fairly narrow 
headcoil and for subjects with a large head, the inserts couple with the 
coil and amplify the gradient noise for the subject. In practice, this 
places a limit on the head width of the subjects we can recruit and at 
the moment we are limited to recruiting subjects whose head is less than 
14 cm wide, which excludes most males and a large number of females.

Does anyone has any experience with other MR-compatible insert systems 
and could provide advice, in particular with respect to:
- the flatness of the transfer function
- how much space the inserts take, whether they are made of hard 
material and how much they stick out of the subject's ears
- any other desirable or undesirable features

Thanks in advance

Julien

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Julien Besle
Senior Investigator Scientist
MRC Institute of Hearing Research
University Park
Nottingham NG7 2RD
United Kingdom

tel: +44 (0)115 951 8508 Ext 209
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