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Experimental_Music_Assignment_2/essay/U1265119-Experimental_Music-Assignment2-Essay.tex
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transducer (such as a microphone or guitar pickup) and amplifier,
causing previously amplified audio to be reamplified continuously at an
exponential rate as illustrated in Figure~\ref{acoustic_feedback}.\\
\begin{figure}[H]
\begin{figure}
\makebox[\textwidth]{\includegraphics[width=\textwidth]{acoustic_feedback_diagram}}
\caption[Caption for LOF]{Acoustic Feedback Diagram\protect\footnotemark}
\label{acoustic_feedback}
@@ -155,7 +155,7 @@
controlling the results of a feedback system. By attenuating an output
before feeding it back to a system, it is possible to ensure that outputs
do not grow at an exponential rate.~\parencite[p.71-72]{zolzer2011dafx}
\begin{figure}[H]
\begin{figure}
\makebox[\textwidth]{\includegraphics[width=0.75\textwidth]{IIR_flow_diagram}}
\caption[Caption for LOF]{Basic Feedback Signal Flowchart\protect\footnotemark}
\label{feed_flowchart}
@@ -341,39 +341,100 @@
the typical guitar feedback example mentioned in section~\ref{variance}
\subsection{Rhythmic/Temporal Implications of Feedback}
The process of feeding a signal back through a system has consequences in
terms of a subsequent iteration's rhythms. The superposition of signals
causes alterations in the temporal content of the subsequenct signals,
resulting in the removal and addition of temporal peaks to the signal (a
signal's peaks are linked to the perceived characteristic of the signal's
rhythm). The effects of feedback are discussed at length with regards to
Alvin Lucier's "I am sitting in a room" by
Weisert~\parencite[p.64-68]{weisert2010ioi}. The rhythmic impact of a
feedback system is complex. However, at a basic level, it should be
understood that feedback causes a shift in rhythmic content over time. The
exact rhythmic alteration is dependant on factors such as the feedback
system, input signal and it's relationship with the subsequent iterations
of itself.
\subsection{Spectral Implications of Feedback}
As with rhythmic content, feedback has a complex effect on the spectral
content of a signal. As with the rhythmic content, the effect of
superposition on the original signal emphasizes and reduces spectral
content. This is again, examined at length in Weisert's analysis of "I am
sitting in a room" and a similar shift in spectral content can be observed
to that of the rhythmic content over
time.~\parencite[p.60-64]{weisert2010ioi}
\subsection{Dynamic Implications of Artificial Amplitude Adjustment}
Used in isolation in alters the sound by a given factor.
Used as part of feedback it acts as an exponent to the output on each
iteration, creating a an dynamic alteration that changes as a function of
time.
The artificial ajustment of audio amplitude is an important technique as it
allows for the alteration of a signal's energy. This acts as a form of
sonic magnifier, able to make inaudibley small sounds audible, as
demonstrated in pieces such as John Cage's "Cartridge
Music"~\citeyearpar{cage2013cm} and Stockhausen's "Mikrophonie"
collection~\citeyearpar{stockhausen1995mmt}. This technique was instrumental in the
development of electroacoustic music by artists such as cage and
stockhausen as it allowed the details of quiet sounds to be amplified
artificially in a live environment.~\cite[p.351-352]{holmes2012eaem}
This process is combined with the principals of a feedback system in order
to provide control to a feedback system. By altering the amplification of
signals in a feedback system, dynamic control of feedback properties is
possible. This is clearly used in works such as Robert Ashley's "The
Wolfman" in order to tune the feedback in an appropriate
fashion.~\cite[p.186]{holmes2012eaem}
\section{Composition Analysis}
There are a large number of peices that utilise electronic feedback
creatively. This section analyses some of the most prominent peices in
order to present some explorations and useages of feedback in experimental
music.
\subsection{Acoustic Feedback}
\subsubsection{Steve Reich's Pendulum Music}\label{pendulum}
~\parencite[p.31]{reich2002wom}
\subsubsection{Robert Ashley's The Wolfman}\label{wolfman}
\subsubsection{Steve Reich's Pendulum Music~\parencite[p.31]{reich2002wom}}\label{pendulum}
This piece is possibly one of the most direct explorations of acoustic
feedback. Where other pieces the effects of feedback on an external source,
Pendulum Music focuses directly on the sonic phenomena generated purely by
the feedback system and the acoustics of the space~\parencite[p.50-51]{weisert2010ioi}.
Aesthetically the piece begins with clear rhythms created by the distinct
motion of the microphones as they pass over the speakers. This slowly
degrades as the microphones lose momentum, resulting in the pure feedback
tones created as the microphones hang motionless over the speaker at the
end. Interesting phase relationships can be observed between the
microphones as the piece progresses, which is in keeping with Reichs works
such as Come Out~\citeyearpar{reich1966comeout}
This piece has a clear focus on process and was described as "the ultimate
process piece" by Reich. Designed as an "audible scupture", the piece is
designed to limit interaction in order to focus on the natural interaction
of acoustic feedback. Control of aesthetics is determined by the
semi-indeterministic method of releasing the suspended microphones, then
allowing natural swinging motions to dictate sonic events and rhythms. This
process is described as semi indeterministic, as it is clear that the
microphones will swing back and fourth at diminishing amounts over time,
however the audible feedback, interplay between audible events, feedback
tone etc\ldots are largely left to chance. This created a stark contrast
between the compositional process and chaos process presented through the
uncontrolled feedback~\parencite[p.186]{holmes2012eaem}.
\subsubsection{Robert Ashley's The Wolfman~\citeyearpar{ashley2003w}}\label{wolfman}
- ref: kyle gann - robert ashley
~\citeyearpar{ashley2003w}
\subsection{Electronic Feedback}\label{ElecFeed}
\subsubsection{David Tutor's Untitled (1996), Toneburst (2004), and Pulsers
(1996)}
~\citeyearpar{tudor1996twfle}
~\citeyearpar{tudor2004lem}
~\citeyearpar{tudor1996twfle}
\subsubsection{Gordon Mumma's Hornpipe}\label{hornpipe}
~\citeyearpar{mumma2002lem}
\subsubsection{David Tutor's Untitled~\citeyearpar{tudor1996twfle}, Toneburst~\citeyearpar{tudor2004lem}, and Pulsers~\citeyearpar{tudor1996twfle}}
\subsubsection{Gordon Mumma's Hornpipe~\citeyearpar{mumma2002lem}}\label{hornpipe}
A combination of electronic and person process due to the sound produced by
the electronic circuitry's interplay with the human improvisation in
reaction to create the final result.
Indeterministic due to the relative unpredictability of the electronic
circuitry.
\subsection{Amplification}\label{amp}
\subsubsection{John Cage's Cartridge Music}
~\citeyearpar{cage2013cm}
\subsubsection{Stockhausen's Mikrophonie}
~\citeyearpar{stockhausen1995mmt}
\subsubsection{John Cage's Cartridge Music~\citeyearpar{cage2013cm}}
\subsubsection{Stockhausen's Mikrophonie~\citeyearpar{stockhausen1995mmt}}
\section{Conclusion}