What can cause a hearing aid, such as the Phonak Virto v90, to raise and lower volume randomly while watching TV?

Most new hearing aid technology now features automatic analysis of your listening environment to react to background noise and take measures when this occurs in order to optimize speech intelligibility for you.  As an example, when you go from a quiet room to a restaurant, the hearing aids may react by initiating its directional microphones to limit the direction you hear sounds so you can focus on the conversation in front of you and not hear the conversation behind you.  These systems can become quite complex as you get to higher level technology, even discerning the difference between music, background noise, car noise, and speech.

Even prior to this, most hearing aids since the 1980s have had a feature known as "compression", which is designed to automatically control loudness and protect your residual hearing.

In either case, these features might just be a set a little too agressive for your preferences.  The trigger point to activate the noise reduction could be set too low, or the compression activating at too low a level.  If you are having issues with perception of volume fluctuations, consult with your audiologist or hearing instrument specialist so that they can make the appropriate adjustments in order to optimize the performance of your hearing aids.

Phonak has an automated system for managing noise.  It sounds like the hearing aid is picking up the sounds from the television and mistaking it for noise...  the noise memory in the automatic sequence will reduce sound, then when it is quieter, it will switch back to the quiet room setting.  Have a special setting for Television made, with no noise reduction.

Many factors that I can think of.  Modern hearing aids have many features that may cause this problem.  The Virto 90 has many sub-programs under the automatic program, and the hearing aid will switch to a sub-program base on the environmental sounds that it detects.  Whenever it detects noise for example, whether it is from the tv or the environment, it will try to lower the "noise" by lower the output gain, and stay in that program until it detects something else then it would get out of that state.  If the transition time is to0 fast, it could cause the hearing aids to "fluctuate".  Try to listen to musics or news, to see if it would manifest.  It it is not, then the transition time on the hearing aids can be changed to a slower time to accommodate for movies where there would be so many different noises.  Or the Specialist can even create a special program w/o compression for that too.  I hope this helps.

Two things come to my mind.

1.  If it happens when the air handler on an air conditioner or fan turns on,  I'd be thinking about the noise management parameters on the hearing aids being too sensitive.

2.  If it happens when the commercials come on then I'd raise the MPO so the hearing aids have more headroom.  

Your Audiologist should be able to help but this is what I've experienced and we've been fortunate to overcome the problem.

Phonak Virto V90 hearing instruments are automatic hearing aids.  If you are not using a TV accessory to link with your hearing aids then it is possible that they are changing due to environmental sounds.  It is also possible that you need to have an adjustment to stop this flucuation.  The fluctuation could be from a change in gain as the hearing instrument changes programs or it may need to have the sensitivity adjusted for which program should be dominate.  I would recommend following up with a hearing healthcare professional to have an adjustment made.

too much compression