OT: Why do people shout into mobile phones?

[Jeff Liebermann]

On Sun, 27 Dec 2009 00:20:00 +1100, F Murtz <haggisz@hotmail.com>
wrote:

N_Cook wrote:
Or is it just a UK pervertion. Anyone would think the technology consists of
baked bean cans separated by a long piece of string.

Depends how far away the other person is, if they are on the other side
of the world you have to shout louder.

That only works with a flat earth. With a round planet, the (virtual)
string between the two tin cans starts to drag on the ground once you
get beyond the horizon, thus causing garble and loss of
intelligibility. Shouting louder does help, but raising the phone
higher in the air helps keep the (virtual) string off the ground.



--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[DaveC]

Or is it just a UK pervertion. Anyone would think the technology consists of
baked bean cans separated by a long piece of string.

Either their cell phone ear piece is so crappy or they don't know how to
increase the volume, either way the received voice is so low that the speaker
unconsciously feels impelled to yell because they think the other person also
can't hear them well.

It does no good to ask these people to speak quietly: they think that this
will cause their friend to not hear them.

Dave

 

[DaveC]

People are used to hearing themselves in the earpiece when talking. In
telco terminology, it's called "sidetone".

http://en.wikipedia.org/wiki/Sidetone

The problem is that there's about a 250 msec audio delay inherent in
digital cellular phone encoding that will drive the user nuts if
there's even the slightest leakage between the sidetone and the
microphone or through the system. Analog cellular did not have the
delay. At best, there will be an echo.
[Jeff L.]

Wouldn't it be simple to amplify the speaker's voice, locally, and mix that
into the receiver circuit for immediate sidetone? No echo, no delay, no
yelling.

Yes, battery life would suffer a bit, but everyone would benefit.

One of those things that phone manufacturers would resist, and only
legislation would make happen.

 

[Phil Allison]

"DaveC"

Wouldn't it be simple to amplify the speaker's voice, locally, and mix
that
into the receiver circuit for immediate sidetone?

** You ACTUALLY deleted the answer to your question.

" In addition, the level of side tone necessary to convince the typical
user that they're getting through, is insufficient to prevent leakage
back into the microphone, especially with a BlueGoof headset. If the
handset manufacturer or cellular vendor added sidetone, you would
instead be complaining about either feedback squeal if injected
locally in the handset or echo if injected at the switch. "

This was immediately after the stuff you quoted.

Wot a moron.


..... Phil

 

[Jeff Liebermann]

On Sun, 27 Dec 2009 16:33:02 -0800, DaveC <invalid@invalid.net> wrote:

People are used to hearing themselves in the earpiece when talking. In
telco terminology, it's called "sidetone".

http://en.wikipedia.org/wiki/Sidetone

The problem is that there's about a 250 msec audio delay inherent in
digital cellular phone encoding that will drive the user nuts if
there's even the slightest leakage between the sidetone and the
microphone or through the system. Analog cellular did not have the
delay. At best, there will be an echo.
[Jeff L.]

Wouldn't it be simple to amplify the speaker's voice, locally, and mix that
into the receiver circuit for immediate sidetone? No echo, no delay, no
yelling.

Yes, it would be "simple" but not very functional. The problem is
that you would also need to limit the microphone AGC range in order to
prevent the sidetone circuit from becoming an acoustic feedback
generator.

In addition, the background noise cancellation circuit will also be
affected. Some of the better cell phones have two microphones. One
for you to yell into. The other to pickup background noise. These
are combined 180 degrees otto phase, resulting in the cancellation of
background noise. Any sidetone that leaks into either microphone is
not going to be balanced with the other microphone, resulting in
feedback.

In addition, the sidetone will need to be disabled when operating as a
speakerphone. That's no problem because everyone yells into a
speakerphone.

However, there is a way to make local sidetone sorta work. A slight
frequency shift (Bode shift) between the microphone audio and the
sidetone audio will prevent feedback. This is what's done on POTS
phones and some VoIP system. You can't hear a 5-10Hz frequency shift,
but it will prevent feedback. (Incidentally, when presented with a
dialup modem tone, the telco echo canceller is disabled. You may not
be able to hear a 5Hz shift, but it will drive the modem nuts).

However, that only solves the feedback problem. The background noise
canceller and speaker phone operation will still need to be dealt
with, or tolerated.

So, why isn't this being done? In order to make it work, one would
need a separate DSP circuit for the sidetone, which is both expensive
possibly messy. Because it's NOT a complete solution, it hasn't been
used. However, it certainly has been tried.

Yes, battery life would suffer a bit, but everyone would benefit.

A little audio has nothing to do with battery life. The biggest
battery hog in a cell phone is the transmitter. 2nd biggest is the
display backlighting. Unless it's a Nextel loud blaster, the audio
circuitry is well down the list.

Incidentally, if you need a demonstration of how much the transmitter
sucks power, put your cell phone in a shielded box, such as a
microwave oven. Presumably, the phone cannot hear the cell site
inside the box. However, it will almost continuously announce it's
presence and listen for a response from the cell site. Average
runtime from fully charged to totally dead seems to be about 4-5 hrs
when I tried it last.

One of those things that phone manufacturers would resist, and only
legislation would make happen.

I think I'm going to lose my dinner. Do you really believe that a
horde of elected officials are even capable of understanding technical
issues? Government is a problem, not a solution.


--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Phil Allison]

"Jeff Liebermann"

However, there is a way to make local sidetone sorta work. A slight
frequency shift (Bode shift) between the microphone audio and the
sidetone audio will prevent feedback. This is what's done on POTS
phones and some VoIP system. You can't hear a 5-10Hz frequency shift,
but it will prevent feedback.

** No way does a 5-10 Hz frequency shift *prevent* acoustic feedback !!

That is a very dopey myth.

The effect of a few Hz shift is to modify the familiar, single frequency
howl into a warbling tone.

The exception is where there is a lot of reverberation in the path from
speaker to mic, causing acoustic gain at multiple specific frequencies. Then
a few Hz shift can produce a useful increase in the threshold before any
disturbance (like ringing) occurs.


...... Phil

 

[Jeff Liebermann]

On Mon, 28 Dec 2009 13:39:16 +1100, "Phil Allison" <phil_a@tpg.com.au>
wrote:

However, there is a way to make local sidetone sorta work. A slight
frequency shift (Bode shift) between the microphone audio and the
sidetone audio will prevent feedback. This is what's done on POTS
phones and some VoIP system. You can't hear a 5-10Hz frequency shift,
but it will prevent feedback.

** No way does a 5-10 Hz frequency shift *prevent* acoustic feedback !!

<http://www.rane.com/note158.html>
Frequency shifting has been used in public address systems to
help control feedback since the 1960's.

The local auditorium has a nifty Bode shifter that works well enough
with some limitations. See below.

That is a very dopey myth.

The effect of a few Hz shift is to modify the familiar, single frequency
howl into a warbling tone.

Maybe. In an uncontrolled environment, it's possible for there to be
positive feedback at specific frequencies and delays. For music, the
maximum frequency shift is 3Hz or less as the ear is very sensitive to
harmonics, which are not quite right with a greater than 3Hz shift.
Piano harmonic partials sound particularly awful. 3Hz is also
insufficient to prevent feedback under all environmental
circumstances. However, for voice quality (PA and cellular), 5-10Hz
works quite well. The current fashion is to continuously vary the
frequency shift. If there are any frequencies where there is positive
feedback, the length of time that the system spends at that frequency
is insufficient for feedback or howl to develop.

The exception is where there is a lot of reverberation in the path from
speaker to mic, causing acoustic gain at multiple specific frequencies. Then
a few Hz shift can produce a useful increase in the threshold before any
disturbance (like ringing) occurs.

Yep. That's the same thing that I just mumbled. My point is that it
can be done with voice and cellular. Music is more problematic.

..... Phil

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Phil Allison]

"Jeff Liebermann"
"Phil Allison"

However, there is a way to make local sidetone sorta work. A slight
frequency shift (Bode shift) between the microphone audio and the
sidetone audio will prevent feedback. This is what's done on POTS
phones and some VoIP system. You can't hear a 5-10Hz frequency shift,
but it will prevent feedback.

** No way does a 5-10 Hz frequency shift *prevent* acoustic feedback !!

http://www.rane.com/note158.html
Frequency shifting has been used in public address systems to
help control feedback since the 1960's.

** Has nothing to do with your false assertion.

Plus I specifically MENTIONED that use in my post.

That is a very dopey myth.

The effect of a few Hz shift is to modify the familiar, single frequency
howl into a warbling tone.

Maybe.

** No maybes about it - it IS what happens, asshole

I have designed a high quality shifter for PA system use - details were
published in Electronics Australia magazine in August of 1997. The maximum
benefit is only 6 to 8 dB in the gain before feedback threshold when the PA
is used in a very reverberant room, like a church.

No benefit exist where *direct path* feedback is the culprit.

However, for voice quality (PA and cellular), 5-10Hz
works quite well.

** There NO similarity between the two apps.

Never noticed how PA systems are often in large buildings with long
reverberation times ???

The exception is where there is a lot of reverberation in the path from
speaker to mic, causing acoustic gain at multiple specific frequencies.
Then
a few Hz shift can produce a useful increase in the threshold before any
disturbance (like ringing) occurs.

Yep. That's the same thing that I just mumbled.

** No asshole.

YOUR words came along in parody of MINE !!

My point is that it can be done with voice and cellular.

** Frequency shifting is of help with VOICE in a PA system - ie where the
" PUBLIC " are being " ADDRESSED" by a speaker. Hence the term.

No way does a 5-10 Hz frequency shift *prevent* acoustic feedback in
general.

Certainly not when the mic and loudspeaker are only inches apart.


...... Phil

 

[Jeff Liebermann]

On Mon, 28 Dec 2009 14:25:22 +1100, "Phil Allison" <phil_a@tpg.com.au>
wrote:

"Jeff Liebermann"
"Phil Allison"

However, there is a way to make local sidetone sorta work. A slight
frequency shift (Bode shift) between the microphone audio and the
sidetone audio will prevent feedback. This is what's done on POTS
phones and some VoIP system. You can't hear a 5-10Hz frequency shift,
but it will prevent feedback.

** No way does a 5-10 Hz frequency shift *prevent* acoustic feedback !!

http://www.rane.com/note158.html
Frequency shifting has been used in public address systems to
help control feedback since the 1960's.

** Has nothing to do with your false assertion.

For the record, my alleged "false assertion" is that a Bode frequency
shifter can be used to reduce or eliminate acoustic feedback in a cell
phone.

Plus I specifically MENTIONED that use in my post.

Ok, I'll give you credit for getting that part right.

That is a very dopey myth.

The effect of a few Hz shift is to modify the familiar, single frequency
howl into a warbling tone.

Maybe.

** No maybes about it - it IS what happens, asshole

My hemorrhoids are none of your business.

I have designed a high quality shifter for PA system use - details were
published in Electronics Australia magazine in August of 1997. The maximum
benefit is only 6 to 8 dB in the gain before feedback threshold when the PA
is used in a very reverberant room, like a church.

I tried to find some details on your design, but only found a thread
where you mentioned it in rec.audio.pro.
<http://www.tomshardware.com/forum/41396-6-quality-pitch-shifter>
I couldn't tell what you used to implement your design. Analog with 2
multipliers and two oscillators 5Hz apart?

No benefit exist where *direct path* feedback is the culprit.

I beg to differ. At the local auditorium, it's common for the speaker
to waltz in front of the loudspeakers with microphone in hand. No
feedback at all. However, when I listen carefully scope, I can hear
reflections from the opposite wall. The only screwup seem to be when
the microphone is very directional and pointed at the opposite wall.
That sounds like a dying Klingon warship.

However, for voice quality (PA and cellular), 5-10Hz
works quite well.

** There NO similarity between the two apps.

Agreed. PA has to deal with the room acoustics. A cell phone doesn't
have enough speaker acoustic power for the room to make any
difference. In any case, the users head is going to block any room
reflections.

Never noticed how PA systems are often in large buildings with long
reverberation times ???

I don't do commercial audio, so the answer is no, I have never
noticed. However, in my checkered past, I helped build and debug 2
recording studios. My job was getting the hum out of the system but I
also helped with the room acoustics. We didn't have Bode shifters at
the time, so I was not able to try one in a studio.

The exception is where there is a lot of reverberation in the path from
speaker to mic, causing acoustic gain at multiple specific frequencies.
Then
a few Hz shift can produce a useful increase in the threshold before any
disturbance (like ringing) occurs.

Yep. That's the same thing that I just mumbled.

** No asshole.

YOUR words came along in parody of MINE !!

I didn't read your concluding paragraph until after I scribbled mine.
I added a little detail explaining how it worked, something lacking in
your explanation. Rather than just erase what I wrote and agree with
you, I gave you credit and left it as is. Try really hard not to
assume that every line I scribble disagrees with everything you write.

My point is that it can be done with voice and cellular.

** Frequency shifting is of help with VOICE in a PA system - ie where the
" PUBLIC " are being " ADDRESSED" by a speaker. Hence the term.

Well, I'll admit that I haven't built a DSP audio processor with a 5Hz
shift suitable for testing on a cell phone. I might be totally wrong,
but you haven't bothered to supply a reason why I'm wrong about it
working in a cell phone.

No way does a 5-10 Hz frequency shift *prevent* acoustic feedback in
general.

If you throw in room acoustics, you're right. If you don't have to
deal with room acoustics, because you head is blocking the earphone,
it's not a problem and Bode shifting will help with feedback.

Certainly not when the mic and loudspeaker are only inches apart.

Actually, it works better when there's a direct path. As you
indicated, it's the reflections that cause problems.

..... Phil

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Phil Allison]

"Jeff Liebermann"
"Phil Allison"

( snip this congenital IDIOT'S idea of bullshitting his way out )

I have designed a high quality shifter for PA system use - details were
published in Electronics Australia magazine in August of 1997. The maximum
benefit is only 6 to 8 dB in the gain before feedback threshold when the
PA
is used in a very reverberant room, like a church.


No benefit exist where *direct path* feedback is the culprit.

I beg to differ.

** Beg all you like.

Only demonstrates your pig ignorance.

Never noticed how PA systems are often in large buildings with long
reverberation times ???

I don't do commercial audio, so the answer is no,

** How fucking asinine !!!!!!!

Wot a fuckwit jerk off.

YOUR words came along in parody of MINE !!

I didn't read your concluding paragraph until after I scribbled mine.

** Pays to read the whole of a post before jerking off in print.

It was only EIGHT lines long !!!

Big strain for you tiny brain was it ??

My point is that it can be done with voice and cellular.

** Frequency shifting is of help with VOICE in a PA system - ie where
the
" PUBLIC " are being " ADDRESSED" by a speaker. Hence the term.

Well, I'll admit that I haven't built a DSP audio processor with a 5Hz
shift suitable for testing on a cell phone. I might be totally wrong,

** YOU ARE TOTALLY WRONG !!!

but you haven't bothered to supply a reason why I'm wrong about it
working in a cell phone.

** Been posted over and over.

No way does a 5-10 Hz frequency shift *prevent* acoustic feedback in
general.

If you throw in room acoustics, you're right.

** The DIRECT OPPOSITE is the case.

Shifters reduce feedback in REVERBERANT rooms.

The more REVERBERANT the room, the better they work.

Certainly not when the mic and loudspeaker are only inches apart.

Actually, it works better when there's a direct path.

** Yaaawnnnnnnn........

You are nothing but a PATHETIC LAIR & DAMN TROLL

FOAD.



...... Phil

 

[Smitty Two]

In article <hgvmr6$vj5$1@news.eternal-september.org>,
"N_Cook" <diverse@tcp.co.uk> wrote:

Or is it just a UK pervertion. Anyone would think the technology consists of
baked bean cans separated by a long piece of string.

One thing I didn't see anyone else mention is that we tend to use cell
phones in noisy environments. When I'm driving I hear a fair amount of
road and wind noise, and when I'm out in a public place there is
traffic, music, other people talking, whatever. So, it makes it hard for
me to hear the person to whom I'm talking on the cell phone. That makes
me want to talk louder, which of course is illogical because my party
isn't hearing my background din.

 

[Jim Yanik]

Smitty Two <prestwhich@earthlink.net> wrote in
newsrestwhich-F2BFC5.10423102012010@newsfarm.iad.highwinds-media.com:

In article <hgvmr6$vj5$1@news.eternal-september.org>,
"N_Cook" <diverse@tcp.co.uk> wrote:

Or is it just a UK pervertion. Anyone would think the technology
consists of baked bean cans separated by a long piece of string.

One thing I didn't see anyone else mention is that we tend to use cell
phones in noisy environments. When I'm driving I hear a fair amount of
road and wind noise, and when I'm out in a public place there is
traffic, music, other people talking, whatever. So, it makes it hard
for me to hear the person to whom I'm talking on the cell phone. That
makes me want to talk louder, which of course is illogical because my
party isn't hearing my background din.

do you remember when there were phone booths?
the ones you could close the door and even sit down to talk?
I can remember when phone booths were made of wood(real oak),and were found
inside drug stores.(where you could buy a milk shake and a burger..)

--
Jim Yanik
jyanik
at
localnet
dot com