Archive for the 'Bitacora' Category

Jun 23rd 2011 resampling wavefiles

I needed to resample some wavefiles for a project. In first instance, I used Audacity (1.3.13-beta) running in a MacBook Pro. After finding many aliasing errors I went back to analyze the results of the resampling. Here some pics:

The results with  Audacity ® 1.3.13-beta (Unicode) and Matlab are much noisier than those obtained with Praat.

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Apr 18th 2011 Some anthropometrics

Related to music and sound:

one syllabe \approx 150-250 ms (Schegloff, 2000)
between-speaker silence 200 ms (Walker & Triboli, 1982)
fastest a human can react to some stimulus with a vocal response under maximally conditions \approx. 200 ms (Fry,1975; Izdebski & Shipp, 1978; Shipp & al., 1984)

mm Hz MIDI
forefinger breadth (mm) 17 20235.29 135.28
thumb breadth (mm) 21 16380.95 131.62
hand breadth without thumb (mm) 85 4047.06 107.42
foot breadth (mm) 97 3546.39 105.13
head breadth (mm) 148 2324.32 97.81
thigh clearance (mm) 154 2233.77 97.13
chin-crown height (mm) 194 1773.20 93.13
hand length (mm) 195 1764.10 93.04
abdominal depth (mm) 244 1409.84 89.16
elbow height sitting (mm) 250 1376.00 88.74
foot length (mm) 256 1343.75 88.33
elbow-grip length (mm) 344 1000.00 83.21
hip breadth (mm) 392 877.55 80.95
shoulder breadth (bi-deltoid) (mm) 447 769.57 78.68
popliteal height (mm) 462 744.59 78.11
breadth over the elbows (mm) 466 738.20 77.96
elbow-finger tip length (mm) 466 738.20 77.96
buttock-popliteal depth (mm) 511 673.19 76.36
shoulder height sitting (mm) 612 562.09 73.24
buttock-knee depth (mm) 625 550.40 72.88
reach depth (mm) 785 438.22 68.93
eye height sitting (mm) 808 425.74 68.43
fist height standing (mm) 878 391.80 66.99
hip height (mm) 924 372.29 66.11
sitting height (mm) 926 371.49 66.07
elbow height (mm) 1133 303.62 62.58
shoulder height (mm) 1444 238.23 58.38
eye height (standing) (mm) 1652 208.23 56.05
stature (mm) 1770 194.35 54.8

Source: http://dined.io.tudelft.nl/dined/# (Dutch (18-30 y) mixed 2003)

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Sep 27th 2009 roughness and pitch

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Jul 26th 2009 occam’s razor and Pope

advise to anyone doing research:

The simplest explanation is the best.

“A little learning is a dangerous thing; drink deep, or taste not the Pierian spring: there shallow draughts intoxicate the brain, and drinking largely sobers us again.”

http://en.wikisource.org/wiki/An_Essay_on_Criticism

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Apr 23rd 2009 Protected: lyrics

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Feb 8th 2009 Running Windows applications in Mac

Don’t pay for  commercial applications like crossover. Use  Darwine:

http://darwine.sourceforge.net/team.php

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Feb 4th 2009 on regress() and F-test.

When using Matlab regress() function, the F-test and its p-value tells how good the regression is:

Quoting from this site:

“The F test is used to test the significance of R, which is the same as testing the significance of R2, which is the same as testing the significance of the regression model as a whole. If prob(F) < .05, then the model is considered significantly better than would be expected by chance and we reject the null hypothesis of no linear relationship of y to the independents. F is a function of R2, the number of independents, and the number of cases. F is computed with k and (n – k – 1) degrees of freedom, where k = number of terms in the equation not counting the constant.
F = [R2/k]/[(1 – R2 )/(n – k – 1)]. Alternatively, F is the ratio of mean square for the model (labeled Regression) divided by mean square for error (labeled Residual), where the mean square are the respective sums of squares divided by the degrees of freedom. Thus in the figure below, F = 16.129/2.294 = 7.031.”

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Nov 14th 2008 Playing WAVE multichannel audio from a browser

Introduction:

Most programs can create multichannel WAVE audio files, but they fail in creating in such a way that they are actually playable in multichannel. I used Mathematica, Audacity, Matlab, Amadeus Pro, and Ardour, to create the sounds and they sound good when I played them from within the application, but when I exported it and played with Quicktime, all the channels were collapsed in only two. Audacity is especially deceiving because you can change the parameters in the preference panel to let you record multichannel files, and when you export, it actually asks you for the mapping of tracks and channels, however, when you listen to it using quicktime, it doesn’t work.

Explanation:

These programs are saving the file with WAVE PCM format instead of WAVE Extensible format. See the differences here:

http://www.microsoft.com/whdc/device/audio/multichaud.mspx

My Solution:

Generate your files with 6 channels in Audacity (btw, I don’t know if it will work with more channels) and keep in mind the standard distribution of the channels:
1. Front Left – FL
2. Front Right – FR
3. Front Center – FC
4. Low Frequency – LF
5. Back Left – BL
6. Back Right – BR

use mctools to convert them to WAVE Extensible format:

http://people.bath.ac.uk/masrwd/mctools.html

This toolkit works in Windoze and Mac, it comes with an utility called copysfx that does exaclty that:

your_prompt$ ./copysfx -t4 inputFile outputFile

(type only the name of the command for help instructions)

I found useful this tcsh script for batch processing:

foreach f (`ls /the_full_path_directory_where_you_have_your_files/*.wav`)
./copysfx -t4 $f $f.wav
end

Save it as toWAV-EX.tcsh, give it execution permission (chmod -744 toWAV-EX.tcsh) and execute from the mctools directory with tcsh toWAV-EX.tcsh

Your converted files are going to be in the same directory of the originals, and have double ‘wav’ extension. Change the name as you wish.

Voila! Now you can play it from Quicktime and therefore from the browser (I worked with Safari and Firefox). Also, be sure your card is multichannel!!! and for me it worked using JackOS to route the audio, I don’t know if you can achieve similar results without it.

that’s it.

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Aug 4th 2008 On reality tests

Joshua Roebke, in an Seed article (may/June 2008), talks to Markus Aspelmeyer, Brukner and Kofler and says that the reason we see our world as we do (without quantum effects) is because of what we use to observe it.

This reminds me the tuning dilemma.

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Jun 9th 2008 Roughness, Chimps and Chumps

According to Fishman et All, roughness maybe represented in auditory cortex (A1) by oscillatory neuronal ensemble responses phase-locked to the amplitude-modulated temporal envelope of complex tones.

Musical Dissonance is highly cultural dependent. See Apel 1973, and Burns and Ward 1982

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