[wordup] Follow up on Mosquito Alarm Stuff
Adam Shand
ashand at wetafx.co.nz
Fri Jun 2 03:33:19 EDT 2006
All right, so this whole story generated quite a bit of response from
various people who think that it's a hoax, that cell phone speakers
can't generate those tones and various other things. So I got a
friend to help me and did some research. :-)
It turns out that the supplied mosquito mp3 from the BBC did indeed
have a bunch of sound in the right frequency band. I got Chris to
strip out the street sounds in the background and tested it on his
cell phone from which he reported nothing over 4KHz making out of the
speaker. I haven't yet managed to figure out how to load an MP3
ring tone into my cell phone but once I get that sorted I'll see if
my fancy RAZR V3i is any better.
I put the mosquito MP3 into iTunes (attached to the email with and
without street sounds), plugged in my headphones (semi-decent Sony
ones), cranked the volume up to max and handed it around my office.
Interesting, over 10% of the people I gave the headphones to had a
nearly visceral reaction and ripped the headphones off their heads
(heh ... yay for volume).
So I'd guess that these Mosquito Alarms might be more effective at
keeping adults away then most stores expect :-)
Adam.
PS. Read the attached thread from bottom up for maximum sense.
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Begin forwarded message:
> From: Chris Winter <mrwinter at mrwinter...>
> Date: 31 May 2006 8:07:06 PM
> To: Adam Shand <adam at shand...>
> Subject: Re: I need expert sound advice! :-)
>
> Well, my highly inconclusive evidence (and rough as guts test)
> shows that there is nothing above 4K coming out of y cellphone
> speaker when I play the recorded sample back thru it.
>
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> Who knows though - phones with mp3 players in them should be
> capable of it quite easily in theory.
> If you can find one of them I can test it for ya...
>
> C.
>
>
Begin forwarded message:
> From: Chris Winter <mrwinter at mrwinter...>
> Date: 31 May 2006 7:59:06 PM
> To: Adam Shand <adam at shand.net>
> Subject: Re: I need expert sound advice! :-)
>
> Ah.
>
> sorry - I missed the whole question.
> You want ME to find out whether phones can generate 16K!
>
> Let me try with mine... but I'll wait until tomorrow so I don't
> wake the sleeping girls trying numerous rings to see what 16k
> content there is...
>
> Actually, now I think about it there may be an easier way...
>
> Hold tight...
>
> C.
>
Begin forwarded message:
> From: Chris Winter <mrwinter at mrwinter...>
> Date: 31 May 2006 7:44:24 PM
> To: Adam Shand <adam at shand.net>
> Subject: Re: I need expert sound advice! :-)
>
> Hey.
>
> Expert sound advice you shall have...
>
> Here's a screen shot of the original sound (you may want to make
> your email window big so you can the detail):
>
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>
>
> The big bump at 16Khz (16000) is the sound that you're talking
> about. The other frequencies to the left are the street sounds.
> I can just hear it - and I know I have a limit of 17k at best (on a
> good day). Too much rock n roll as a kid ruined the top 3K.
>
> Here's a screen shot of me taking out the other frequencies ( a
> tiny bit left around 1- 2K but I did a real rush job on it for ya):
>
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>
> Note that I got most of everything out except the 16K stuff.
> I can still hear the noise but it's far less audible - mostly
> because the gain has dropped on the signal when I did the
> processing. You can hear the really high snippets of talking etc
> that are mainly high frequency sounds being reflected off surfaces
> around what sounds like the mall - the walls, glass, maybe the
> table top etc.
>
> Here's an AAC file of the mosquito sound on its own. You may need
> some good cans and a decent volume level on it to hear it - but
> it's there...
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>
> So the short answer is - yes it's certainly possible - and more so
> because teachers are exposed to high levels of high pitched
> screaming, shouting, etc on a regular basis and that portion of
> their hearing tends to be most fucked. Age also plays a large
> factor in the equation and we all tend to lose our high frequencies
> in our hearing first. They'd have no idea that the phone was ringing.
> On the other hand, most teenagers have already lost a fair bit of
> hearing these days due to music, tv, games, movies etc etc etc... I
> think they would find it difficult to hear the phone in anything
> other than a reasonably quiet room. At a guess, I'd say there's too
> much noise pollution in streets etc as you can hear in the mp3 to
> be able to pick it out on a crowded street, for example. The other
> thing is, how do you differentiate between tones when you're
> hanging out with your friends. You'd need a reasonable sample
> editor to cut it into something you recognise. Not too difficult
> though...
>
> Whether the cellphone speakers can generate the frequencies - I
> don't know. I would assume that they can - it's much easier to
> reproduce high pitched frequencies on a small speaker like is in a
> cellphone than low frequencies.
>
> Now it's your job to find out which cellphones can reproduce 16k
> thru their ring speaker...
>
> C.
>
>
> On 31/05/2006, at 5:47 PM, Adam Shand wrote:
>
>> okay don't know if you've heard of this but it seems that some
>> company has devised a device which outputs a very high pitched
>> sound which teenagers can hear but most adults can't (called the
>> mosquito alarm). this part is apparently true.
>>
>> however the rumour mill now says that teenagers have recorded the
>> sound and are using it as a ringtone on their cell phones which
>> they can hear but teachers etc can't. sounds awesome, but the
>> question is ... can cell phone speakers generate the high
>> frequencies required?
>>
>> supposedly the below mp3 is a recording of one of the mosquito
>> alarms, can you open it in one of your fancy things and see if
>> there really is high frequency sounds in there?
>>
>> http://www.bbc.co.uk/wiltshire/audio/mosquito_sound.mp3
>>
>> next ... is it easy to filter out the street noise so we have an
>> mp3 with just the high pitched stuff?
>>
>> i'm mildly fascinated by this and want to see if it's really
>> possible or not :-)
>>
>> Begin forwarded message:
>>
>>> From: Lucas Sheehan <lsheehan at pixelworks...>
>>> Date: 31 May 2006 2:16:58 AM
>>> To: Adam Shand <adam at shand...>
>>> Subject: Re: [wordup] Mosquito Alarm
>>>
>>> I read this as well and found it great however doing some further
>>> investigation there is some contention that cell phone speakers
>>> would not be able to reproduce the ?Mosquito? alarm. Either way
>>> its cool.
>>>
>>> Cheers,
>>>
>>> Lucas
>>>
>>> On 5/29/06 12:11 AM, "Adam Shand" <adam at shand...> wrote:
>>>
>>>> Awesome ...
>>>>
>>>> Adam.
>>>>
>>>> From: http://www.metro.co.uk/weird/article.html?
>>>> in_article_id=14031&in_page_id=2
>>>>
>>>> Pupils perform 'alarming' feat
>>>> Wednesday, May 24, 2006
>>>> A high-pitched alarm which cannot be heard by adults has been
>>>> hijacked by schoolchildren to create ringtones so they can get away
>>>> with using phones in class.
>>>>
>>>> Techno-savvy pupils have adapted the Mosquito alarm, used to drive
>>>> teenage gangs away from shopping centres.
>>>>
>>>> The alarm, which has been praised by police, is highly effective
>>>> because its ultra-high sound can be heard only by youths but not by
>>>> most people over 20.
>>>>
>>>> Schoolchildren have recorded the sound, which they named Teen Buzz,
>>>> and spread it from phone to phone via text messages and Bluetooth
>>>> technology.
>>>>
>>>> Now they can receive calls and texts during lessons without
>>>> teachers
>>>> having the faintest idea what is going on.
>>>>
>>>> A secondary school teacher in Cardiff said: 'All the kids were
>>>> laughing about something, but I didn't know what. They know phones
>>>> must be turned off during school. They could all hear somebody's
>>>> phone ringing but I couldn't hear a thing.
>>>>
>>>> 'One of the other children told me all about it later. I
>>>> couldn't be
>>>> too cross, because it shows resourcefulness.'
>>>>
>>>> The Mosquito technology is said to play on a medical phenomenon
>>>> called presbycusis, or age-related hearing loss.
>>>>
>>>> It is thought to begin at 20 and first affect the highest
>>>> frequencies
>>>> ? 18 to 20kHz.
>>>>
>>>> The device was developed by Merthyr Tydfil-based Compound Security.
>>>>
>>>> Boss Howard Stapleton said: 'I think it is a giggle. A teacher
>>>> would
>>>> be able to hear the sound only from 1m away. Teenagers could
>>>> hear it
>>>> from much further away.'
>>>>
>>>> But why don't pupils just set their phones to vibrate?
>>>> --
>>>> List: http://www.spack.org/index.cgi/WordUp
>>>> More: http://www.spack.org/index.cgi/AdamShand
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