Unusual High-Frequency Beeps From ReSound Quattro's After Removal From Charger?!



Anyone know why ReSound Quattro’s might omit high-frequency beeps for no particularly good reason?

I had been charging my Quattro’s in their charger case, observing the % charge via the phone app, and chitchatting with my wife. As both Quattro’s reached the % charge I wanted, I removed them from the charging part of the case, put them in the carrying part of the case.

In a minute or two my wife asked, “What the heck is that high-frequency beeping noise?!” (I should say that standard signal beep on the devices is set to “low-frequency” as I have ski-slope high frequency hearing loss).

With my hearing loss, I couldn’t hear what she was talking about but I launched a frequency analyzer on my phone and it showed a sharp peak at 4.7 KHz. The wife insisted it was the hearing aids in their case and as soon as I picked them up out of the case the beeping stopped, both by her perception and the frequency analyzer analysis.

One possibility is just when charging I have been willy-nilly inserting the HA’s and removing them from the charging part of the case. Each time you remove one, it causes it to reboot and I’ve wondered whether it would screw them up if you just promptly inserted them back into the case, which I do sometimes without waiting for them to stop rebooting, usually because I willy-nilly decide I want to charge them some more. But the normal beeps associated with rebooting are low-frequency, as noted above. The other possibility is somehow that plopping them down in the case on a power switch caused the switch to be depressed but I don’t think that could have happened with enough force/weight to depress a switch to any extent. Another far-out possibility is that 4.8 KHz is the frequency the Tone Generator app was set to run at when I blasted my ears the other night fooling around with tone generation. At the time of the unusual beeping just now, my HA’s were connected to my phone via BT but the TG app was not running and does not have permission to run in the background.

Both Quattro’s show that they are charged to about 60% so it’s not one of the HA’s signalling that it’s battery is dying. And strange that the beeping stopped as soon as they were picked up (what made me entertain the switch depression hypothesis). I guess the “don’t stick them right back in the charger just after you’ve removed them” is still a possible explanation of how I temporarily screwed one up.

Edit_Update: Wife thinks HA’s might have been picking up strong EMF from some nearby electronic device so will try to replicate situation another day


Hi Jim,

By putting the Quattros from the charger to the (as you called it) carrying part they will start up and generate feedback.
In my opinion there is not any reason to take the Quattros out of the charger when not in use.


Thanks for the suggestion. Having two “on” hearing aids right next to each other with their mics and receivers both on might be my problem! - and my luck, perhaps I had them oriented receiver to mic, like the numbers 69. So perhaps I don’t want to repeat to verify - although my audi when first setting them up, plopped the HA’s in the charging wells, then pulled them out, and plopped them in front of her Noahlink Wireless to connect them to her Smart Fit software, so I have seen a provider put my two “on” Quattro’s side-by-side.

I never charge my HA’s to 100%-so I don’t want to just keep them in the case charging when I’m not using them. So I turn them off when I go to sleep. If you never go over 80% charge, you can supposedly at least double the number of possible charge cycles of a Li-ion battery, so as I announced in another thread back at the end of October, 2018, I am deliberately conducting an experiment to see how much lifespan I can get out of a set of Quattro’s. As some folks recommend taking a break from your HA’s, I deliberately charge them for 20 to 30 min when I get up in the morning and am eating breakfast, dressing. Then I charge them for another 20 to 30 min in the evening when I’m taking a break. My % charge usually ranges between about 35% to 65% charged, which allows me to go 9 hours easily before my “break” without dipping below 30% charge or so. Since I have a Lowe Pro belt case, I can carry the charger (battery pack) case anywhere with me. Besides just testing whether I get more lifespan than any other Quattro (or other rechargeable) user, perhaps my scheme will help assure that my Quattro’s will still have a strong enough battery to serve as backup HA’s when I want to move on to something else (since they’re my first and only HA’s so far and I have no backup right now). The charge scheme that I am actually using according to some should treble or quadruple the lifespan of my Li-ion batteries (see the Android Accubattery app in Google Play for extending phone battery lifespan).


Here’s PVC’s suggested test to check out the mics/receiver of an HA. But usually when I dump my HA’s in the charger case, the bodies of the HA’s are both down next to each other, the HA receivers are up in the air together, almost sticking out of the case - so it is pretty unlikely that I rested the HA’s with the receiver on one against a mic on the other.

Based on the loudness of the beep might wife heard, wearing an HA while bringing a receiver close to a mic may not be a good idea, at least for a Quattro.


A few months back after I was getting severe feedback with classical music and really high woman’s voices, that 69 configuration is how my HIS set them on his desk and connected to Smart Fit, and could duplicate the feedback. He adjusted the feedback and some overall volumes in my Music program to resolve it.

This might not be what happened, but from my experience with the ReSound Forte / Linx 3D, it seems quite possible.


I don’t think that two hearing aids in a “69” configuration will generate feedback because it’s not a loop. Feedback Loop: In this example, a signal received by the microphone is amplified and passed out of the loudspeaker. The sound from the loudspeaker can then be received by the microphone again, amplified further, and then passed out through the loudspeaker again.

But either hearing aid by itself when placed in an enclosed area (maybe the “carrying part” that I saw referenced) will likely cause a feedback loop. You can cause a feedback loop by simply cupping your hearing aid inside your hand, or lying on a pillow, or hugging another person.


btw> It’s not a “carrying part”. It’s a Receiver bay;


If you want to use the Receiver bay as a carrying case then turn the Quattro’s off;
Your hearing aids are automatically turned on when they are removed from the hearing aid charger. They can also be turned on and off manually by pressing the push button for 5 seconds.


Thanks for all the helpful suggestions. My wife is normally turned off by all the blah-blah-blah she hears from me about my HA’s but in this instance, for some reason, she’s incredibly gung-ho to get to the bottom of the problem (maybe because she can hear the 4.7 KHz tone and I can’t without my HA’s?! - making her feel like she has a special duty or ability in this instance to help the handicapped?!). So maybe we’ll know more later after I get done being her experimental subject!


OTH, if you ever listen to any radio shows that take “call-ins,” you might have experienced a positive feedback loop between two devices. I think these days with time delays in broadcasting and DSP, call-on-the-air feedback loops have been greatly reduced or eliminated but in the good ol’ days when someone placed a call to a radio station and had the telephone too close to the radio in their home, you could get a tremendous feedback loop. It’s my recollection that you can do this, too, playing around with your cell phone and a landline. If you call your home landline and bring your cell phone close and speak into one phone, it’s off you go, as best I can remember, with a pretty decent feedback loop. Anything that “catches” and amplifies sound and sends it back to its place of origin seems to have the potential, to ignorant ol’ me, to become a positive feedback loop.


I think the phone/radio problem is latency, not an audio feedback loop.


Not sure how “latency” makes the looped sound volume go out of control - it’s the amplification factor in a loop that makes it positive (or negative) feedback loop:

Nuclear fission is an interesting example of a positive feedback loop. The splitting of U-235 after absorbing a neutron does not occur instantaneously. There is a finite (but very small time delay). Yet it is the extreme example of a feedback loop that never actually comes back to its origin as defined above. The important thing is that > 1 neutron (usually something like 2.5 avg) is produced with each fission, quickly exponentially amplifying the number of subsequent fission events that can take place. A stable nuclear power plant has to moderate free neutron availability to exactly 1.0000… new neutrons available on average as a result of each event. >1 meltdown or boom. <1, reactor goes offline. I guess fission does grossly fit the description that A produces more of B, which in turn produces more of A. Somehow the product stimulates more of what produced it. Perhaps exactly how that happened is immaterial.

" A chain reaction is a sequence of reactions where a reactive product or by-product causes additional reactions to take place. In a chain reaction, positive feedback leads to a self-amplifying chain of events."

From: Chain reaction - Wikipedia

The Wikipedia Positive Feedback article has lots of examples of positive feedback both in nature, biology, electronics, audio, video, and human social systems.


It doesn’t. When a person hears his/her own voice in real time and then hears the same words repeated a second or two later then he/she becomes confused and cannot continue to speak.

When the radio broadcasting person recognizes this confusion he tells the caller to turn the radio off.

This is the only phone/radio problem that I know about and it’s caused by latency. I have never heard of an audio feedback loop between a radio and a phone??


As I previously mentioned, I think both digital signal processing and the time delay that ~all “live” radio shows use per FCC edict to prevent the broadcast of profanity on the air have changed things from the days of yore - perhaps I am a bit older than you (I’m almost 73).

Since audio feedback in “live” calls to radio stations is almost a thing of the past, it is hard to find references to it. But here’s one. It’s from 2006 (13 years ago) and the highlighted “answer” is from someone who used to work for a talk radio station - according to the poster.

I think just as for feedback from digital hearing aids as compared to analog, radio stations have come such a long way from the early days. Feedback suppressor - Wikipedia A time delay in broadcasting (and also the latency inherent in DSP processing) helps prevent but does not eliminate the chances for audio feedback. Light travels 186 miles in a millisecond. So in the good ol’ days of live radio with a live telephone call to the radio station, a loud radio speaker playing next to a telephone receiver connected to a local radio station 20 or 30 miles away is just about equivalent to a microphone placed right next to a speaker when the whole audio system, including the amplifier in between, is in the same room. A (sound into telephone receiver) produces B (amplified sound out of a loud radio speaker) which produces more A ( even more amplified sound into telephone receiver to be amplified yet again running through system). Poorly set up PA systems are just another example of the same phenomenon where a speaker misuses the mic and subjects everyone to an ear-splitting squeal, e.g., someone uses a mic that’s not highly carotid and sends the sound from the PA system back into the mic to be further amplified.


Hmmmmm; We are getting off into the weeds by referencing AskMetafilter’s “I think” comments.

Perhaps feedback can occur between two hearing aids next to each other. But why does that matter since it can occur with only one hearing aid?

Have your wife try these two experiments, the first should produce no feedback;

No feedback:

  • Remove HAs from charger (this will turn the hearing aids on)
  • Turn Both HAs off and then put both HAs in the Receiver Bay


  • Remove HAs from charger (this will turn the hearing aids on)
  • Turn one HA off and then put both HAs in the Receiver Bay


@pvc Thanks for the suggestions.

I have found that it is feedback from the two HA’s on together in the receiver bay just by using my Android frequency analyzer (the wife is at work actually doing something useful as compared to me!).

The LEFT one when on and placed in the receiver bay along with the right one off and in the bay can generate the feedback for a short period of time after being turned on but the feedback dies away. If the RIGHT one is also on, the feedback is sustained. The RIGHT one on by itself with the left one off does not seem to generate feedback (different size domes are on the receiver ends, medium power on right, small power on left).

I didn’t experiment with a whole bunch of placement configurations. I just put the HA’s with the bodies down at the bottom of the bay but with the receiver wires rising up but because of the bend in the wire to insert into the ear canal, the receivers are pointing back down into the top of the bay, over the receiver body of the other HA. The HA’s are in a 6 to 9 configuration but the receivers are NOT right next to the mics of either HA - but in the proximity.

The exact frequencies generated perhaps depend on the actual placement and way the wires are leaning. So it probably is some resonant frequency thing where the HA noise background output by one HA is picked up by the mics of the other and the resonant frequencies turn out to be relatively high pitch.

So thanks to everyone, especially pvc, for their help. I learned a lesson. Do not put both your HA’s together when turned on, especially in a hard plastic semi-open cavity that probably makes a great sound resonance chamber (duh to me!)! :blush:

The left HA behaves a little funky in a couple other ways but I haven’t very well investigated its other idiosyncrasies.


By-and-large, though, the highlighted commenters @ the AskMetaFilter link seemed to know what they were talking about. I learned a lot about acoustic feedback traveling through the weeds!

One of the more interesting things that I learned about acoustic feedback is that time delay in the circuit involved does not prevent acoustic feedback. In fact, it even increases the possibilities for it but it also greatly increases the time constant for feedback exponentially building up. So perhaps a 7 second delay gives the station enough time to get the caller to do something about a radio still on as judged by the echo effect without having feedback go out of control.

This 2005 article on feedback and suppression may be a bit ancient but it examines the phenomenon in detail, including the effects of time delay in a circuit. It discusses how a relatively slight pullback in gain can suppress feedback, which is what sound engineers do with equalizers in “ringing out” an auditorium so perhaps with DSP, radio stations can now do that on the fly to callers foolish enough not to turn down their radios: