There have been similar complaints this past week. Someone pointed out that the noise is coming from CRLS HVAC system. See:
https://seeclickfix.com/web_portal/WacEfzPx7m29dubrPfXEEwCV/issues/8431163
https://seeclickfix.com/web_portal/WacEfzPx7m29dubrPfXEEwCV/issues/8433337
https://seeclickfix.com/web_portal/WacEfzPx7m29dubrPfXEEwCV/issues/8458357

So I got curious and walked over to where the sound was coming from. It's a bit vexing due to the reflections off so many buildings, and you can hear the sound clearly at least as far as Inman Square because of the way the sound is reflected off buildings down the channel of Cambridge Street. I believe the sound is caused by some kind of resonance in one of the five tall metal exhaust stacks coming up from the point where the High School meets the War Memorial Building. (You can cup your hands around your ears and it works like a pretty accurate direction finder.)

It seems to me that all you have to do is turn off one at a time whatever source is exhausting into those five pipes and diagnose the problem. The cure may be as simple as installing a baffle in the problematic pipe in order to eliminate the resonance. It's really quite ridiculous that this problem has been allowed to continue for so long.

Kudos Robert Winters!

@Rober Winters: THANK you for making that effort!!

I heard it las night, too.I could hear it at the same time stated by Mr. Winters from my westward-facing porch, and it did seem to be coming from the Cambridge Hospital or further west (Spaulding, CRLS, Library or War Memorial - all would have been on that list, especially given that many 3-story buildings block a direct hit from the noise to my porch).

I agree, too, that this has been allowed to go on way too long. As we wind down our last days of true summer, during a pandemic, is it too much to ask that we can enjoy the fresh air offered by open windows, porch lounge chairs, or a simple walk?

If there is a designated employee (or other) with a number we can call to alert the appropriate City department when the noise starts, perhaps they can get over there and do what Mr. Winters did to isolate (and END!!) this terribly unwelcome visitor to our otherwise peaceful neighborhoods.

Please get this fixed!

Thank you -
A Tax-Paying Homeowner

Last night (Aug 29) there were at least four of us (Denise H., Rob P., me, and another fellow whose name I didn't get) who were out independently investigating this. Shortly after I became reasonably sure of the source we saw a couple of guys on the roof with flashlights checking out that area. They came out of the building a short time later and I'm guessing they soon cut off the source, so let's give credit to the staff people for (finally) getting to the root of the problem and let's hope it doesn't return!

If it does return, who ya gonna call? Noisebusters!

Ha ha haaa.... thanks for the coda!

there are several strings dealing with this issue.
It goes back about 10 years. it is a failure to maintain the boilers in the war memorial building. the high efficiency gas boilers have scale that builds up in the vent pipes. this narrows the opening and causes the noise. i have been complaining for years and the response was to turn off the offending boiler. they have five. the solution is to do regular maintenance with a solution that dissolves the scale. they do not do it.
I appreciate everyone who is emailing calling and complaining. One voice is not listened to.
please do not stop.
or the problem will continue.

Does the high school have a dedicated long-time maintenance staff who keep track of problems like this and who can address problems as they arise? I know that other City maintenance functions are contracted out and institutional memory suffers. Every building needs a "go to guy" (or gal). It's great that Bob Skenderian knows the specific causes, but I would hope that the custodial staff are as well informed and empowered to address problems as they arise.

Maybe replace the boilers? They're probably about 500 years old....

only 11 years old. the person in charge of maintenance would just turn off the boiler that was making the noise.
not get it serviced.
I had been the only one complaining about the sound for years. last year one other person complained and I felt such relief. I was not alone.
You are correct Robert Winters there should be a consistent maintenance plan.
poor execution.

City Hall – DR assigned this issue to Cambridge Public Schools

First of all, I apologize for any inconvenience this is causing you.
We have shut of all boilers last week and complaints have continued. We conducted multiple walk-troughs on the roof and couldn't hear any excessive noise. The noise was reported to be random, starting at various times and lasting from 10 minutes to an hour.Most reports said either evening or morning hours.
We had staff on the roof starting Friday night, Saturday and Sunday morning and evening. We were able to pinpoint one air handling unit and the unit was shut down Saturday night around 10 pm.
Our contractor is on the roof today trying to determine if anything else is making excessive noise. We will have staff on the roof again tonight to listen for any issues.
I sincerely apologize for having to deal with this. We are trying to locate the issue and address it. Thank you.

Thank you for working on this and sharing the details. I personally have not heard any noise since the unit was shut down Saturday night.

Thanks so much for looking into this and for taking the time to reply. I haven’t heard any noise either since Saturday night, so perhaps you’ve found the culprit.

Thank you so much for looking into this and being committed to solving it!

Hi,
I received another complaint about the noise and would like to ask if you have heard anything since couple of weeks ago. Please let me know either way. Thank you.

We have not heard it since my first message, but we have been out of town for the past four days, so I can’t speak for that time.

it went off about 8pm last night

Same as before or a different sound? Same duration? Only at 8pm? Thanks

I can hear a high pitched noise from my house at highland Ave and Cambridge street right now at 10pm. It is higher pitched and much softer than the noise we were hearing in late August. I hear this when I step outside, but it is not loud enough to resonate through my house or be especially noticeable like the previous noise.

I'd like to close this issue