What if QuickSin results on one ear show that while the loss is aidable, you need +30dB for any chance at speech perception in noise while the other ear is at +6dB? What if QuickSin results on one ear show that you may never be able to deliver speech perception in one ear, while the other aidable ear will manage with a decent hearing aid? Is there an argument against fitting an aid to the worst ear, or is there an argument for fitting a Bi-CROS system? These and other things are the things that spin through my head, you really don’t want to know about the other things in there. Even me and the voices are a little scared some times!
The question first occurred to me recently when discussing the failure of the fitting of binaural hearing aids for some Patients with hearing losses that appeared to be eminently suitable for amplification. In the hypothetical case it was put forward that the Patient would get on better with just one hearing aid, fitted in the ear that they perceived to be better. The possibility of poor or no speech perception in one ear because of some unknown neuro cognitive difficulty could be the answer. Something that we could assess if QuickSin tests were undertaken monaurally giving us separate scores for each ear.
So my brain went on overdrive, as it is want to do sometimes, and worried at the problem. First I considered monaural fit, however, then I thought that perhaps a Bi-CROS fit would be a better option, allowing us to deliver a wider source of auditory data and delivering spatial awareness without the problems caused by direct amplification to the worse ear.
Here is the problem I see though, with what we know about auditory deprivation and the gathering evidence in relation to untreated hearing loss, is it cavalier or negligent of us not to deliver amplification to the worse ear? I would put forward that a well fit Bi-CROS will reduce the cognitive load needed to hear better, therefore may well meet the requirements. However, I am not sure and I don’t think we really can be until we know more about the connection between un-treated hearing loss and neuro cognitive disorders.
Does a happy Patient trump established thought?
Here is the kicker, if we fit the Patient with this type of presentation with a Bi-CROS and they get on exceptionally well, does that trump the established and scientifically validated fitting protocol? I have discussed this with a couple of people, now I would like to hear from you, let me know what you think?
There is a piece of the puzzle which is missing, and one we also find in “bimodal” CI-HA fittings, as sometimes the aided speech perception goes *down* when the hearing aid is worn on the unimplanted ear. The missing piece of the puzzle is the aided speech perception in quiet in that ear, as that indicates whether the loss is purely sensorineural, or if there is neural firing dys-synchrony present, i.e. the speech is distorted or clear.
Basically, BiCROS would be used if amplifying the bad ear causes the speech perception to drop.
Part and parcel to this is determining if there are any cochlear dead zones, and also screening for ANSD by measuring ipsi acoustic reflex thresholds across the speech range.
Editor, The Hearing Blog
A really interesting proposal, Geoff! I would suggest that QuickSIN results should be combined with the ANL test for an even better understanding of why some hearing aid fittings, bilateral or unilateral, provide lower than expected benefit in noisier listening conditions. Even the results of both tests won’t improvement management in all cases but at least it informs decisions about the most appropriate technology/rehabilitation strategy to a much greater extent than reliance only on a pure-tone audiogram. Best regards, Barry
Thank you both for your contributions