Music 680: Special Topics in Music Theory - Electronics in Performance (Fall 2006)
Class 5: October 9, 2006

Pauline Oliveros / Bye Bye Butterfly (1965)
	tape delay as constructive principle: repetition and magnification
	recorded improvisation and the found object

Pauline Oliveros 
	"Tape Delay Techniques for Electronic Music Composers" in Software for People
		discussion of music for "The Bath" as an analog version of sample-and-hold
			the tape recorder as an agent for musical memory
		using the term "reverberation" where delay is more appropriate
			(although the Lucier-style "recursive room recording" situation is certainly reverberant)
	"Acoustic and Virtual Space as a Dynamic Element of Music" in The Roots of the Moment
		book as hypertextual collage
		the developing nature of the EIS over time 
		including the addition of a second performer, and then software control
		"Whatever I played could come back as a delay and be layered with the present moment or be 
			modified by pitch-bending or modulation. At the same time I had to be anticipating the 
			future of the sound that I was making in the present moment."

Pauline Oliveros / "Reason in Madness Mixed" from Crone Music (1989)
	the Expanded Instrument System (EIS)
	real-time spatial processing (delay, reverberation) applied to improvisation

Pd techniques
	delay lines
		delwrite~/delread~ pairs
			where multiple delread~ objects (taps) can be used with each delwrite~
		vd~ as a replacement for delread~
			for time-varying taps
			note that this produces sampling-rate conversion (pitch shift)
				used extensively by Oliveros in Crone Music
	filtering
		as delay: design of a one-zero highpass or lowpass filter
			lowpass: y[n] = x[n] + x[n-1]
			highpass: y[n] = x[n] - x[n-1]
		comb filtering: recursive filter structures
			y[n] = x[n] - (c * y[n-m])
				where c is the feedback coefficient (c < 1)
				and m is the delay in samples (lowest comb frequency = sampling rate / 2m)
				delay in samples = sampling rate / lowest comb frequency (D = fs/f)
				delay in msec = 1000D/fs = D/44.1
				if f = 220 Hz, D = 44100/220 = 200.4545, D(ms) = 4.5454
	reverberation
		Schroeder design: as a network of comb and allpass filters
		rev3~ as a high-quality built-in reverberator
			four parameters: output level (dB), liveness (%), crossover frequency (Hz), HF damping (%)