Inspired by a thread discussing police blotters, where a man was in a police station when he received a call from a scammer. The call was then forwarded to the officers cell phone when the officer proceeded to blow his whistle into the phone when the scammer called…
So my question is, what is the loudest noise I could easily send from my cell phone and have it be received at an uncomfortable level on the receiving end?
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The loudness of the receiver’s cell phone or similar device is determined by the volume setting. Someone blowing an air horn at one end might be heard as a barely audible whup at the other end if the receiver has the volume turned way down.
The key is difference in volume. If the caller whispers so that the receiver increases the cell phone volume and then hits the big decibels, the receiver is in for a surprise.
The max volume of a cell phone varies depending on model.
Old fashioned land lines sometimes come with a volume adjustment but some don’t. So this trick may not work on the latter.
Thanks for the response, and I got all that. One would assume that the receiver’s volume would be set at a level to hear ‘normal’ conversation. Also, I know that voice compression technology cuts out the high and low ends of the audible spectrum to make more efficient use of available bandwidth, so a whistle, while being very loud, may not receive the same way yelling into the phone might.
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The microphone in the whistler’s phone will also be a limiting factor. Beyond some volume level, the microphone will just distort or break up.
Right. So the question isn’t “what’s the loudest noise able to travel through a phone?”
It should be “What’s the loudest noise I can cause another phone’s speaker to produce?”
And the answer is that you can only do so much. Take a picture of the sun and email it to your buddy and have him look at it. The picture of the sun will only be as bright as the screen of his device.
Yes, I would suggest reading for context, but I don’t think I could have been more clear in the second paragraph of my original post. So, just read.
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OP, you might want to find the option “Signature” in either your phone or in a Tapatalk settings.
Unless you’re really into that one.
Regards,
Leo Bloom
Also, the landline phone companies have limits on how high a volume (how much electricity) they let travel through their lines. (Too much increases cross-talk (where you faintly hear another conversation in the background).) Most of this is limited by the carbon microphone in your handset, but they also had controls at the Central Office to handle this.
I suspect the cellphone companies have similar limits built into the phones. There is probably an FCC limit on the watts that a cellphine can transmit over the airwaves.
The analog telephone exchange powers the handsets, and so the power supply put on the phone line would limit the power returned… the exchange has a short circuit cut off so that flooded lines don’t drain all the exchange’s power into a short circuit…
I think the “exchange power” issue,and the lengths that the telephone exchange workers went to maintain backup batteries - huge room filled with batteries, staff risking hydrogen explosisions,etc… they had shower in there with foot pedal turn on… just get yourself to the shower and you get a wash to wash the sulfuric acid off… ,etc
The power issue meant that the telephone exchange would only provide enough power to drive the handset at the reasonably loud volume… In fact, the power was only just enough to drive one or two handsets ringing, and any larger ringer or pabx would require its own power … not enough power from the telephone line.
Now, the OP says “blow a whistle”… whats happening there is that the power is concentrated into a narrow frequency range… therefore more volume possible!
In rough terms, power = bandwidth * volume, you see.
Now the radio transmitters would have strict limits on the transmitters amplifier… (max current -> max electric field made by the antenna… ) so that there is a maximum volume … The gov sets a limit of the field strength transmitted, which would only an issue at the tower…but its often specified as the power used by a dipole antenna to transmit a carrier (a simple sine wave ) of (containing) that field strength… so it can be written as a power. Not that this radio topic matters with digital, digital would use the same power no matter what volume the audio…
This is my field… B.Eng. (Computer Engineering which is a modification of Electrical Engineering course… I could have chosen to effectively complete Electrical even if the name on the degree was Computer )
Back in the analog/landline days my hearing-impaired mother had an amplified telephone. There were no special connections or power source, just an additional volume knob next to the roatary dial.
When we turned it up all the way it could be uncomfortably loud, but not at the level that might actually damage normal hearing. I imagine a whistle would have been extremely piercing at full volume.
Today’s cellphones all transmit the sound encoded digitally. The wattage of the signal is practically unrelated to the contents.
ETA: Which I now see has already been pointed out. I blame being hung over.
Back when I still had a landline, I kept a Fox40 whistle by the phone to mess with unwanted callers. I stopped using it when somebody warned me that it could be dangerous/illegal.
Unless you live somewhere very remote and are calling someone nearby, your classic landline is only analog from phone to exchange.* Once it hits an exchange, it’s converted to digital and that is sent to the exchange of the caller. Loudness is limited during the A to D conversion.