Auditory Illusions

General

– There are a lot of Illusions in “Psychoacoustics” of Music, for Example the simple Fact that different Timbres / Sound Layers combined are changing the Fundamental and Overtones in Time due to constantly changing Harmonics per Note and Timbre / Sound Layer

Illusion Examples

Missing Fundamental Illusion 

– although we Do Not hear the Low Frequencies of a Man´s Voice on a Telephone, we Re-Produce the Voice as a Man´s Voice because of the Overtone Structure

Scale Illusion

– Diane Deutsch did many Psychoacoustic Researches, Listen to Example as if we would go Up & Down a Scale, In Fact it´s just a Jumping Pattern (your Brain is trained to hear Scales)

Whole Pattern

De-Constructed Left / Right

Scala Illusion (Tchaikovsky)

Whole Violin Section

Melody of 1st 16 Violins

Melody of 2nd 14 Violins

Full Context “The Opening”

Shepard Tones

– a Tone that somehow moves Endlessly & at the same Time manages to get Back where it started

– the Key is that each Note is a Symphony of different Frequencies

– Imagine a Infinite Keyboard +/- , you Play every Single A´s on the Keyboard, then A#, then B etc. and by the Time you get to the A again, you Repeat All over from where you Started Originally (because you Play every Single Key on the Keyboard)

– by Infinite Keyboard is simply meant any Keyboard where Quasi its Full Octave Range is used as Start and End Point in Low and High Register

– That´s how you constantly Move Up a Semitone and Manage to go Back (actually Shepard Tones work in a Circle)

– Now because we Perceive Notes only as Low as a Particular Value and High as a Particular Value, you Play Middle Keys Loud but Low & High Keys get Quieter and Quieter in Register (to avoid Notes Jumping In from Low Side or Creeping Out on High Side because of the Circling Notes) 

Velocity Envelope to Fade-In and Fade-Out Tones

Falling Bells

– Similarity to Shepard Tones

– Notes are seems to Rise but they “Fall” over Time 

– the Key is again make that Shepard Semitone Movement where at the sameTime the Velocity Envelope is Moving Downwards

– In this case from the One to the Next the Pitch is definitely Going Up, but over Time due to the Envelope it Draws the Pitches Lower and Lower

Tritone Paradox

– as a Foundation is the simple Tritone Interval of Six Semitones

Q:

–  What you are about to hear are 4 Pairs of Notes, Listen if goes from a Higher Note to a Lower Note or from Lower Note to a Higher Note ? (do you go on the Piano to the Left or to the Right ?)

A: 

– What we Did is take the Shepard Tones we had before and we are Playing 2 of them that are 6 Semitones apart (Imagine this Interval Fills a whole Circle)

– to Explain further, Imagine Playing All A´s on Keyboard (Shepard Tones), then Move to All D Sharps by a Tri-Tone Interval, you might Do this Going from A Up to D# or Going from A Down to D# 

– So Neither Up Nor Down is our Example, since a Interval of 6 Semitone is based on Equal Notes across the Keyboard, in either Direction (as the Exact Middle of an Octave), 

– you simply can’t Distinguish Higher or Lower, even though the Frequencies are helping, but Once we build that Pattern you can’t compare the Entire Note

– The Example contains Pair 1 = G#2 to D2 (Up), Pair 2 = F2 to B2 (Down), Pair 3 = G2 to C#2 (Up), Pair 4 = E2 to A#2 (Down)