Office noise masking DIY question

[zound]

I have a new job with a small enclosed office. I can close the door but at normal volume on the phone my neighbors can hear almost every word. I've had two people warn me that everyone can hear each other's calls.

I'm looking for some good ideas for masking sound. I have a great white noise machine that blocks ME from hearing others if I put it in my office. But I want to block OTHERS from hearing me. I can't stick a white noise machine in my neighbors' offices, so am thinking about how to direct friendly-level white noise or masking sound to theirs. What's a good way to do that... just point a speaker at the wall and play white noise? Seems like it would just make me have to speak slightly louder.

Clearly I'm not an audio engineer here, so any ideas would be appreciated

[Don Hills]

Generating masking noise will just annoy your neighbours. White noise won't be suitable because most of the noise will be reflected / absorbed by the walls. You'd need to use noise concentrated in the vocal frequencies - such as a radio tuned to a talkback station.

I think your most practical option will be to build a "cone of silence". A box or hood, heavily lined with sound absorbent material, that you face into when speaking on the phone.

[pinkmouse]

If it's confidential work related calls, then it's up to management to sort out the problem. If it's personal, then anything you is likely to raise suspicions and get you fired.

[sreten]

Hi,

I'm an ex telecoms engineer.

The sound from the mouthpiece is fed back to the earpiece to seem
natural and this feedback mechanism to a degree determines how
loud you talk.

Bizarrely to most people, when you have blocked ears you talk
very quietly, this is because you hear your own voice more through
bone conduction in your head than usual, you try to match your
feedback speech level to what you are hearing, being external its
much lower, which the ear being clever adapts to, but the feedback
mechanism doesn't, so bizarrely with blocked ears people can't
understand you because you speak too quietly rather than the
case being other way round.

Using an earpiece / headphones and a microphone the simple
option is to reduce the incoming earpiece volume and also
possibly increase the mouthpiece to earpiece feedback level.
Both will tend to make you speak quieter.

But basically reduce your earpiece volume as low as possible.
In a quiet office environment it should not be an issue.

Also FWIW some people have a habit of talking extremely loudly
into telephones. It makes no real difference whatsoever as to
what the person at the other end can hear, all you get is the
local mouthpiece / earpiece feedback telling you your loud.

(Unless you've got lots of background noise, then it works.)

That is not what the other end hears though they can tell
you are being loud, for them you are just as intelligible
at normal speaking volumes, you might sound more
reasonable and considered by not being loud.

rgds, sreten.

[SY]

A Fenton Silencer. (see "Tales of the White Hart")

[zound]

Originally Posted by sreten

Hi,

I'm an ex telecoms engineer.

The sound from the mouthpiece is fed back to the earpiece to seem
natural and this feedback mechanism to a degree determines how
loud you talk.

Bizarrely to most people, when you have blocked ears you talk
very quietly, this is because you hear your own voice more through
bone conduction in your head than usual, you try to match your
feedback speech level to what you are hearing, being external its
much lower, which the ear being clever adapts to, but the feedback
mechanism doesn't, so bizarrely with blocked ears people can't
understand you because you speak too quietly rather than the
case being other way round.

Using an earpiece / headphones and a microphone the simple
option is to reduce the incoming earpiece volume and also
possibly increase the mouthpiece to earpiece feedback level.
Both will tend to make you speak quieter.

But basically reduce your earpiece volume as low as possible.
In a quiet office environment it should not be an issue.

Also FWIW some people have a habit of talking extremely loudly
into telephones. It makes no real difference whatsoever as to
what the person at the other end can hear, all you get is the
local mouthpiece / earpiece feedback telling you your loud.

(Unless you've got lots of background noise, then it works.)

That is not what the other end hears though they can tell
you are being loud, for them you are just as intelligible
at normal speaking volumes, you might sound more
reasonable and considered by not being loud.

rgds, sreten.

Thank you! This is extremely helpful. I will take this advice and reduce earpiece volume. It is also interesting because it explains why I see others talking so loudly on cell phones at times. I assumed they just didn't care how loud they were, but now I can see how the feedback mechanism has been affected.

One question though, reducing earpiece volume makes sense, but to "increase the mouthpiece to earpiece feedback level"... wouldn't that have the same affect as increasing earpiece volume and make me talk louder? I don't understand that part.

As for a couple of other posts... I was thinking when I gave the speaker pointed at the wall example it would make me sound like the worst office neighbor ever. I would not sonically assault anyone and was trying to spur some creative ideas. Still I appreciate your humor.

As for the cone of silence idea... I laughed because I was actually thinking that hanging some sound absorbers might really help. I'm not going to cover my walls like a recording studio, but maybe a decorative quilt or something would help. I'll give it a shot.

Thanks!

[sreten]

Originally Posted by zound

One question though, reducing earpiece volume makes sense, but to
"increase the mouthpiece to earpiece feedback level"... wouldn't that
have the same affect as increasing earpiece volume and make me
talk louder? I don't understand that part.

Thanks!

Hi,

No, of the feedback level is too high you will speak lower to balance
the incoming speech level, and you might have howlaround feedback
problems between the earpiece and mouthpiece.

Avoiding that feedback can mean the injected mouthpiece signal
into the earpiece signal is too low and you tend to speak louder.

FWIW as you have your own office and assuming there is not
a lot of background noise, a decent speakerphone might help.
As long as you are near it you can speak at normal speech levels.

If people can still hear almost every word your "enclosed office"
is next to useless regarding verbal privacy, the "party" walls
would need looking at.

rgds, sreten.

[zound]

Thanks again, Sreten. I'll give a speakerphone a shot.