[PD] Headphones question on pd list

[Jonathan Wilkes]

----- Original Message -----
> From: Charles Henry <czhenry at gmail.com>
> To: Jonathan Wilkes <jancsika at yahoo.com>; pd-list at iem.at
> Cc: 
> Sent: Thursday, August 25, 2011 12:22 PM
> Subject: Re: [PD] Headphones question on pd list
> 
> On Wed, Aug 24, 2011 at 5:40 PM, Jonathan Wilkes <jancsika at yahoo.com> 
> wrote:
>> 
>>  Without knowing anything in advance about the speakers being used, is there 
> a way to construct some kind of [aural-faxbomb~] that outputs in the -1 to 1 
> range which could be used generally to at least get in the ballpark of what you 
> want the maximum level of perceived loudness to be when wearing headphones?
> 
> You should be able to pick a suitable frequency band.  A reasonable
> expectation is that headphones can produce sounds between 200Hz and
> 20kHz.  Loudness seems to fall off pretty quickly above 10kHZ, so
> there's no point in including much of the higher frequencies, if
> avoidable.
> 
>>  Maybe another way to ask: can you construct an example patch with output 
> that is louder than [noise~]--[*~ max_float_value]--[clip~ -1 1]--[dac~]?
> 
> The spectrum distributes energy to frequencies that will not be
> reproduced or perceived loudly (which should be the case for the
> above, having a very flat spectrum).  If the sound gets focused into a
> smaller band, which is more relevant for speakers/hearing, the
> loudness will be greater.
> 
> I think one place to start looking is a non-bandlimited square wave
> function.  It's known that this kind of function has odd-numbered
> partials that fall off according to 1/n, or in other words, the power
> spectral density falls off at -6dB/octave.
> 
> The only problem with this function is that again the sound could be
> more focused into a narrower band.  One thing that comes to mind is
> multiplying square waves together (since this keeps the values at
> +1/-1), but that would only distribute more energy to higher
> frequencies.  What about PWM?
> 
> I think we are designing the worst possible sound here.  "Sound check.
> Play the horrible noise, so we know nothing that comes after that can
> sound as horrible."

That's what I meant by [aural-faxbomb~].  A fax bomb is a completely black 
page continuously sent to a fax machine, which uses up all the ink.  I would imagine 
that this sound, continuously played, would wear out the speakers -- not to mention
one's ears.  But one could use it as a reference point to set levels.  (I'm not sure
an actual faxbomb has any use other than wreaking havoc.)

-Jonathan

>