Sound Examples for Chapter 4: Auditory Perception

[S:32] Equal Power Noises (EqualPower.mp3 0:16). The sound alternates between a Gaussian noise and a Uniform noise every second. The noises have been "equalized" so that they have the same power. Though the waveform clearly shows the distinction (see Fig. 4.3 on p.  pageref), it sounds steady and undifferentiated to the ear.


[S:33] Regular Interval T: These sound examples present a regular sequence of identical clicks with exactly T ms between each click. Perceptions vary by tempo. Tones are heard with small T, rhythms for medium T, and unconnected isolated clicks for large T.


(RegInt2.mp3 0:20), (RegInt5.mp3 0:20), (RegInt10.mp3 0:20), (RegInt20.mp3 0:20), (RegInt33.mp3 0:20),
(RegInt50.mp3 0:20), (RegInt100.mp3 0:20), (RegInt333.mp3 0:20), (RegInt500.mp3 0:20), (RegInt750.mp3 0:20), (RegInt1000.mp3 0:20), (RegInt3000.mp3 0:20), (RegInt5000.mp3 0:20)

[S:34] Speed-Up Events (SpeedUpEvent.mp3 2:33) As the tempo increases, the events become closer together, eventually passing through the various regimes of perception. Condenses the examples of [S:33] into one sound file.

[S:35] Randomly Spaced Ticks (GeoTick.mp3 0:20) (NormTick.mp3 0:20) The interval between successive clicks in these examples is random, defined by either the geometric distribution or the normal distribution.


[S:36] Irregular Successions (Irreg40.mp3 1:00), (Irreg400.mp3 1:00), (Irreg4000.mp3 1:00), (Irreg40000.mp3 1:00). The normal (Gaussian) distribution is used to specify the times for the events. The T values specify the average number of events per second that occur at the peak of the distribution.

[S:37] Sweeping Sinusoids (SineSweep.mp3 0:15). Three sinusoids begin at frequencies 150, 500, and 550 and move smoothly to 200, 400, and 600 Hz, respectively. Many complex interactions can be heard as the sinusoids change frequency. When they come to rest on the harmonic series, they merge into one perceptual entity: a note with pitch at 200 Hz.


[S:38] Sweeping Rhythms (SweepRhy1.mp3 1:18), (SweepRhy2.mp3 1:18), (SweepRhy3.mp3 1:18), (SweepRhy4.mp3 1:18). Three steady beats begin with periods 0.38, 0.44, and 0.9 per sec and move smoothly to 0.33, 0.5, and 1.0 per sec, respectively. Many complex interactions can be heard as the successions change period. When they come to rest on the periodic sequence (about 2/3 of the way through) they merge into one perceptual entity: a single rhythmic pattern with period 1 sec. The example is repeated N=4 times. For N=1, the phases of the three beats are aligned when they synchronize. For N=2,3, the phases take on arbitrary values (though the periods remain synchronized). For N=4, the three sequences are performed on different sounds (stick.wav, clave.wav, and tube.wav).


[S:39] Windchime (WindChime1.mp3 1:33). The "ding" separates from the "hum" in these wind chimes as the sound initially fuses and then separates.

[S:40] A Single Chime (WindChime2.mp3 1:20). Created using a normal distribution to specify the times for the events as in [S:35]. Each strike is allowed to ring for its full length. As in [S:39], the "hum" separates from the "strike" though both are clearly present throughout.

[S:41] Streaming Demo (Streaming.mp3 1:57). The three notes defining a major chord are repeated. The notes alternate in timbre, a synthetic trumpet followed by a synthetic flute. When played slowly, the outline of the major chord is prominent. When played more rapidly, the instruments break into two perceptual streams.


[S:42] Regular Durations T: This series of sound examples performs a regular sequence of durations, each of length T ms. The sounds are a guitar pluck and a synth chord. Perceptions vary by tempo. Tones are heard with small T, rhythms for medium T, and unconnected isolated clicks for large T. Thus the perceptions of rhythms may be elicited equally from empty time sequences (like the clicks of ) or from filled-time durations.


(RegDur2.mp3 0:20), (RegDur5.mp3 0:20), (RegDur10.mp3 0:20), (RegDur20.mp3 0:20),
(RegDur33.mp3 0:20), (RegDur50.mp3 0:20), (RegDur100.mp3 0:20), (RegDur333.mp3 0:20),
(RegDur500.mp3 0:20), (RegDur1000.mp3 0:20), (RegDur3000.mp3 0:20), (RegDur5000.mp3 0:20)

[S:43] Speed-Up Durations (SpeedUpDuration.mp3 2:33) As the tempo increases, the durations occur closer together, eventually passing through the various regimes of perception. Condenses the examples of [S: 42] into one file.

[S:44] Irregular Successions of Durations (IrregDur40.mp3 1:00), (IrregDur400.mp3 1:00), (IrregDur4000.mp3 1:00). The normal (Gaussian) distribution is used to specify the durations. The T values specify the average number of durations per second that occur at the peak of the distribution. See Sect. 4.3.5.

[S:45] Best Temporal Grid (TempGrid(b).mp3 0:20), (TempGrid(c).mp3 0:20), (TempGrid(d).mp3 0:20). These perform the sequences shown in parts (b), (c), and (d).


[S:46] Changing Only Pitch (ChangePitch.mp3 0:32). The loudness of each note is equalized; notes are defined by changes in pitch.

[S:47] Changing Only Bandwidth (ChangeBW1.mp3 0:32), (ChangeBW2.mp3 0:32), (ChangeBW3.mp3 0:32) Each "note" is generated by a noise passed through a filter with a specified bandwidth. Loudnesses are equalized and there is no sense of pitch. Each of the three examples uses a different set of bandwidths: all low pass filters in the first, and two kinds of bandpass filters for the second and third.

[S:48] Amplitude Modulations (ChangeModAM1.mp3 0:32), (ChangeModAM2.mp3 0:32) Each "note" is generated by a different rate of amplitude modulation. Loudnesses are equalized and all pitches are the same in the first example. Pitch contours follow those of and in the second example.

[S:49] Frequency Modulations (ChangeModFMsin.mp3 0:32), (ChangeModFMsq.mp3 0:32), (ChangeModFMtri.mp3 0:32) Each "note" is generated by a different rate of frequency modulation. Loudnesses are equalized and all pitches are the same (but for pitch shifts induced by the FM). The three versions use sine wave, square wave and triangular wave as the carrier.

[S:50] Pulsing Silences (PulsingSilences.mp3 3:34). A single harmonic tone enduring throughout the piece is filtered, modulated, made noisy and otherwise manipulated into a "song with one note."
[S:51] Two Periodic Sequences with Phase Differences (Phase0.mp3 0:10), (Phase2.mp3 0:10), (Phase10.mp3 0:10), (Phase20.mp3 0:10), (Phase30.mp3 0:10), (Phase40.mp3 0:10), (Phase50.mp3 0:10) Two regular successions are played each with 0.5 sec between clicks. The two sequences are out of phase by N percent, so that N=50 is a equivalent to a double speed sequence with 0.25 sec per click. Several rhythmic regimes occur, including the flam (2%), rapid doublets (10%), doublets (20%), and a galloping rhythm (30 and 40%).


[S:52] Two Periodic Sequences with T1 not equal to T2. (PhaseLong.mp3 1:40) Two sequences with periods T1=0.5 and T2=0.503 are played. Over time, the sound shifts through all the perceptual regimes of : flamming, doublets, galloping, and double speed.


[S:53] Three Periodic Sequences (Metro3a.mp3 1:40), (Metro3b.mp3 1:40), (Metro3c.mp3 1:40) In a, the three rates are T1=0.5 and T2,3=0.5 ±0.003 sec. In b, the three rates are T1=0.5, T2=0.48, and T3=0.51 sec. In c, the three rates are T1=0.5, T2=0.63, and T3=0.29 sec. The latter two contain some patterns that make rhythmic sense and others that are incomprehensibly complex.

[S:54] Nothing Broken in Seven (Broken7.mp3 3:29). A single six-note isorhythmic melody is repeated over and over, played simultaneously at five different speeds.

[S:55] Phase Seven (Phase7.mp3 3:41). A single eight-note isorhythmic melody is repeated over and over, played simultaneously at five different speeds.

[S:56] One Hundred Metronomes (Metro10.mp3 2:00), (Metro50.mp3 2:00), (Metro100.mp3 2:00) These three examples play N simultaneous regular successions, each with a randomly chosen period. The appearance is of a random cacophony. Inspired by György Ligeti's Poeme Symphonique.

[S:57] Listening to Individual Feature Vectors # 1 Feature vectors for the Maple Leaf Rag are made audible using the technique of Sect. 4.4.2.
  1. (MapleCBFeature9.mp3 0:44) The feature vector from the ninth critical band (before the derivative) gives one of the clearest rhythmic percepts.
  2. (MapleCBFeature9diff.mp3 0:44) The feature vector from the ninth critical band (after the derivative) gives one of the clearest rhythmic percepts.
  3. (MapleCBFeature2.mp3 0:44) The feature vector from the second critical band (before the derivative) gives almost no rhythmic percept.
  4. (MapleCBFeature2diff.mp3 0:44) The feature vector from the second critical band (after the derivative) gives almost no rhythmic percept.


[S:58] Listening to Feature Vectors Feature vectors for the Maple Leaf Rag are made audible using the technique of Sect. 4.4.2. (MapleFeatureAll.mp3 0:44) All the feature vectors (before the derivative) from all the critical bands are summed, leaving a clear rhythmic percept. (MapleFeatureAlldiff.mp3 0:44) All the feature vectors (after the derivative) from all the critical bands are summed, leaving a clear rhythmic percept.

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[S:59] Listening to Individual Feature Vectors # 2 Feature vectors for the Maple Leaf Rag are made audible using the technique of Sect. 4.4.4.
  1. (MapleFeature1.mp3 0:44) The energy feature vector.
  2. (MapleFeature2.mp3 0:44) The group delay feature vector.
  3. (MapleFeature3.mp3 0:44) The spectral center feature vector.
  4. (MapleFeature4.mp3 0:44) The spectral dispersion feature vector.

[S:60] Povel's Sequences (PovelN.mp3 0:20), N=1,2,...,35. The thirty-five sequences from Povel and Essens are ordered from simplest to most complex.
(Povel1.mp3 0:20), (Povel2.mp3 0:20), (Povel3.mp3 0:20), (Povel4.mp3 0:20), (Povel5.mp3 0:20),
(Povel6.mp3 0:20), (Povel7.mp3 0:20), (Povel8.mp3 0:20), (Povel9.mp3 0:20), (Povel10.mp3 0:20),
(Povel11.mp3 0:20), (Povel12.mp3 0:20), (Povel13.mp3 0:20), (Povel14.mp3 0:20), (Povel15.mp3 0:20),
(Povel16.mp3 0:20), (Povel17.mp3 0:20), (Povel18.mp3 0:20), (Povel19.mp3 0:20), (Povel20.mp3 0:20),
(Povel21.mp3 0:20), (Povel22.mp3 0:20), (Povel23.mp3 0:20), (Povel24.mp3 0:20), (Povel25.mp3 0:20),
(Povel26.mp3 0:20), (Povel27.mp3 0:20), (Povel28.mp3 0:20), (Povel29.mp3 0:20), (Povel30.mp3 0:20),
(Povel31.mp3 0:20), (Povel32.mp3 0:20), (Povel33.mp3 0:20), (Povel34.mp3 0:20), (Pove35.mp3 0:20)
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