Hi Alex, all<br><br>...but PDs dB goes to 0, because we have to have the numbers following the same scheme - so that 0 means 0 always I think. Industry uses dBFS (deciBel Full Scale) because it is measuring the signal against the full scale from -96dB in 16bit recordings to 0dB (all bits used). <br><br>Basically, the reason for dB is that our ears hear sound in a non-linear fashion, rather like frequency in fact which is why we have [mtof]<br><br>Each drop of (n)dB will be heard as the same amount of reduction in loudness, whereas every linear drop is different perceptually. So, if you have a signal at 96dBPD (-4dBFS) and you set it to 90dBPD (-10dbFS), the loudness will be heard to drop by the same amount as when you then set it to 84dBPD (-16dBFS). In fact, you have halved the amplitude twice, so it is a quarter of what it was, but each drop is heard as the same. This is the difference between amplitude (linear [*~ ]) and loudness (logarithmic)<br><br>...so
you could relate dB to pitch accounting for the energy at different pitches quite simply, if you use inputs to [dBtorms] and [mtof] in some form of inverse-proportion.<br><br> [dbtorms]<br> |<br>[*~ ]<br><br>Best,<br>Ed<br><b><i><br>Alexandre Quessy <listes@sourcelibre.com></i></b> wrote:<blockquote class="replbq" style="border-left: 2px solid rgb(16, 16, 255); margin-left: 5px; padding-left: 5px;"> Hi all,<br><br>2007/2/8, Frank Barknecht <fbar@footils.org>:<br>> Yes, it's new. You could use the [list-len] abstraction from<br>> [list]-abs instead, but you need to check out an older version,<br>> because the newest one just wraps [list length].<br><br>zexy's [length] also does the job, as far as I know.<br><br>As I can see, I am still very bad at using the dB unit for audio<br>amplitude... Anyone has a rule of thumb for this ? Should I use dB<br>with a simple ADSR filter, let say ? I know that if you use them, -6<br>dB is
somewhat half as loud and +6 dB is twice as loud. Great. Now, in<br>pd, 100 is unity while in the industry, the consoles use 0 for unity<br>level. 0 in pd is minus infinity, as far as I know. Now, what is<br>usable ? After a drop of a few dB, we don't hear anything.<br>Perceptualy, I find the standard [*~] range of numbers more linear<br>than using the dB scale.<br><br>So, the RMS kind of mean the actual amplitude of the vibrating<br>membrane of the speaker... http://en.wikipedia.org/wiki/Audio_power :<br>hence we use [- 100] [dbtorms] for the conversion. Anything else one<br>should know ?<br><br>Perhaps I should put it somewhere on puredata.org after. :)<br>-- <br>Alexandre Quessy<br>http://alexandre.quessy.net<br><br>_______________________________________________<br>PD-list@iem.at mailing list<br>UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list<br></fbar@footils.org></blockquote><br><BR><BR>\/<br> /\<br> |
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