Release_Augmented Audification

Hanns Holger Rutz edited this page Nov 26, 2015 · 5 revisions

'Augmented Audification' Sonification

:back: Release Workshop

:package: Download Template

Description

The sonification targets one-dimensional data. It can be played directly as so-called "audification", using a normally high sampling rate (in the order of several thousand samples per second), or zoom into a region of the data set with a pitch shift and modulation, leading to an "auditory graph".

You may find details on the sound synthesis in this paper: https://smartech.gatech.edu/handle/1853/54113

The time dimension is used to unroll the data in time during playback.

Controls

  • Speed (1/s): number of data points (samples) played per second. (For audification, use, e.g., a sampling rate of 44100 Hz.)
  • Data min: provide the minimum of the data values for correct normalization
  • Data max: provide the maximum of the data values for correct normalization
  • Pitch modulation (octaves): spreads the perceived pitch of (normalized) data values of +/- 1 by +/- one octave
  • Frequency shift (Hz): To be used if the sampling rate is too low for the audible range; suggested factor is between 200-800 Hz.

Data Sets

The sonification can be used with any one-dimensional data set.

For the template, we use:

  • TOA Incident Shortwave radiation: avg_rsdt_Amon_MPI-ESM-LR_historical_r1i1p1_185001-200512.nc (yearly values, i.e., only 156 values - only an auditory graph makes sense here)
  • Data from the WegenerNet, http://wegenernet.org/
    • Air temperature (at 2m) and surface temperature in Feldbach from 11/2007 to 11/2008
    • Air temperature (at 2m) and surface temperature in Feldbach from 11/2011 to 11/2012 (hourly values over one year; missing values have been interpolated before)

The data can be either played with high sampling rate (Speed, e.g., 11000 with Pitch modulation = Frequency shift = 0), or it is possible to zoom into a small area of interest (speed, e.g., 48, i.e. 2 days per second, with a pitch modulation of 1 and a frequency shift of 200).

Patch

// Version: 25-Nov-15_1

def mkDelay(in: GE, buf: GE): GE = {
  val dt = BufDur.kr(buf)
  DelayN.ar(in, dt, dt)
}

// returns (delayed source, shift90)
def HilbertFIR(in: GE, buf: GE): (GE, GE) = {
  val fft   = FFT(buf, in)
  val pv    = PV_PhaseShift90(fft)
  val dly   = mkDelay(in, buf)
  val shift = IFFT.ar(pv)
  (dly, shift)
}

val v       = Var("var")
val dTime   = Dim(v, "time")
val speed   = UserValue("Speed (1/s)", 44100).kr
val lo      = UserValue("Data min" , 0.0).kr
val hi      = UserValue("Data max", 1.0).kr
val time    = dTime.play(speed, maxFreq = 22000)
val raw     = v.play(time, interp = /* 1 */ 2) \ 0
val ok      = CheckBadValues.ar(raw, post = 0) sig_== 0
val clean   = Gate.ar(raw, ok)
// raw .poll(Impulse.kr(speed))
// time.poll(Impulse.kr(speed))
val sig     = clean.linlin(lo, hi, 0 /* -1 */, 1).clip(0, 1)
val c       = UserValue("Pitch modulation", 0.0).kr
val df      = UserValue("Frequency shift (Hz)", 0).kr
val fMod    = df * 2.pow(sig * c)
val sin     = SinOsc.ar(fMod, phase = 0.0)
val cos     = SinOsc.ar(fMod, phase = 0.5 * math.Pi)
val hlbBuf  = LocalBuf(4096)
val (hilbRe, hilbIm) = HilbertFIR(sig, hlbBuf)
val env     = mkDelay(Line.ar(0, 1, 0.1), hlbBuf)
val out     = LeakDC.ar(hilbRe * sin - hilbIm * cos) * env

Elapsed := time
output  := Pan2.ar(out * -6.0.dbamp)
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