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Final version of FYP report. Added proposal for EM assignment 2. Added huddersfield masters proposal updates

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DSP/Assignment_2_report/U1265119_Assignment2_report.tex
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\item D/A \& A/D converters
\end{itemize}
In order to understand the specification of the dsPIC in relation to the
standard of DSPs available, it will be compared to three other digital signal
processors:
In order to understand the specification of the
dsPIC~\parencite{mt2004dspic} in relation to the standard of DSPs
available, it will be compared to three other digital signal processors:
\begin{itemize}
\item Texas Instruments TMS320F2806
\item Freescale 56F8025
\item Analog Devices ADSP-2126
\item Texas Instruments TMS320F2806~\parencite{ti2016pm}
\item Freescale 56F8025~\parencite{fs2006dsc}
\item Analog Devices ADSP-2126~\parencite{ad2012adsp}
\end{itemize}
\subsection{General Computing Factors}
@@ -217,8 +217,8 @@
of calculations must be performed in a set period of time in order to
process audio as quickly as it is provided to the system. If the clock
speed is not sufficient, this may result in instructions being missed due
to an interupt before the processor has been able to complete them. This
can create in artefacts in output audio.~\parencite[p.34]{sd2006mfes}
to an interrupt before the processor has been able to complete them. This
can create artefacts in output audio.~\parencite[p.34]{sd2006mfes}\\
It should be noted that this is not an entirely accurate measurement for
speed as different manufacturers have different definitions of a
@@ -277,7 +277,7 @@
performance. Variations of this have been used in all examples.
\section{DSP Specific Factors}
DSP specific factors relate to components specically affecting the system's
DSP specific factors relate to components specifically affecting the system's
ability to handle audio signals. These will determine the quality of audio
manipulation and affect the computational requirements for the system. This
section briefly covers the computational impact of the DSP specific
@@ -360,11 +360,10 @@
menu button. Parameter variables can then be increased and decreased for
the selected effect using two switches.\\
It was not possible to use the UI in conjunction with any actual audio
effect as proper threading of the menu alongside the DSP process was not
possible. Having the menu run in the same thread as signal processing
forced menu logic to complete at signal rate. When this did not occur this
would create unexpected results and graphical error in the LCD as logic was
not completed fully. As a result, the project presented is a prototype to
effect as the UI would need to be processed after any audio effects. in
practice this caused problems as the program did not always have time to
complete UI logic before the interupt, causing graphical errors and
unexpected results. As a result, the project presented is a prototype to
demonstrate possibilities given a capable system.
\section{Results}
@@ -386,18 +385,35 @@
equally simplistic results in terms of perception. A feedback was not
implemented to differentiate this from the reverb design.
\subsection{Chorus}
The implementation provided a perceptually similar alternative to the
infeasible modulated delay line design from the previous assignment.
infeasible modulated delay line design from the previous assignment.
Each delay can be set to up to a maximum delay time of 250 samples.
This allows for manual shifting of phases to taste. Overall this
results in a functional alternative at the cost of perceptual quality.
Through the use of a spectrogram, it can be seen in figure
\ref{fig:cho_spec} that the signal is clearly noisy and distorted with
harmonics produced far above the nyquist rate. This is most likely due
to the poor converter performance
\begin{figure}[H]
\caption{Chorus spectrogram displaying distortion}
\makebox[\textwidth]{\includegraphics[width=\textwidth]{Chorus_spectrogram}}
\label{fig:cho_spec}
\end{figure}
\subsection{Reverb}
A crude slapback reverb was created using an FIR/IIR filter
combination. The result was a short reverb tail with decaying
repetitions of the dry sample. This would have been vastly improved
with the addition of further parallel comb filters or all pass filters.
A clear decaying echo can be see in figure \ref{fig:rev_wav}
\begin{figure}[H]
\caption{Reverb waveform}
\makebox[\textwidth]{\includegraphics[width=\textwidth]{Click_reverb_waveform}}
\label{fig:rev_wav}
\end{figure}
\section{Further Work}
Building on skills learnt in this project, results could be improved
Experimental_Music_Assignment_2/proposal/EM2_Assign2_Proposal.tex
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\documentclass{scrartcl}
\usepackage{enumitem}
\usepackage[british]{babel}
\usepackage[style=apa, backend=biber]{biblatex}
\DeclareLanguageMapping{british}{british-apa}
\usepackage{mathptmx}
\addtokomafont{disposition}{\rmfamily}
\addbibresource{~/PerryPerrySource/LaTeX/ExperimentalMusic_Bibliography.bib}
\DeclareCiteCommand{\citeyearpar}
{}
{\mkbibparens{\bibhyperref{\printdate}}}
{\multicitedelim}
{}
\begin{document}
\title{Experimental Music\\Formative Assignment 2\\Essay Proposal\\}
\author{Sam Perry\\U1265119}
\subtitle{The role of electronics, feedback and amplification in
experimental music composition.\\}
\date{}
\maketitle
\section{Essay Objectives}
This essay will explore the ways in which prominent composers utilise
electronic devices and systems to compose music; focusing primarily on
feedback and amplification as techniques for creating and manipulating
sounds in both the analog and digital domain. This will provide a detailed
overview of these widely used processing techniques, and will explore the
reasons behind their popularity amongst experimental composers. The
advantages and disadvantages of using these techniques will be explored in
detail with regards to established concepts, and the aesthetics of such
effects.
\section{Subject Rationale}
Electronics have played a key role in the development of experimental music
in the past fifty years and have had a dramatic effect on the ways in which
experimental music is realised. The ability to control amplitude and cause
feedback has influenced a number of compositions, which will be explored in
this essay.\\
Examples of compositions include:
\begin{enumerate}
\item \textbf{Acoustic Feedback}
\begin{itemize}
\item Steve Reich's Pendulum Music~\parencite[p.31]{reich2002wom}
\item Robert Ashley's The Wolfman~\citeyearpar{ashley2003w}
\end{itemize}
\item \textbf{Electronic Feedback}
\begin{itemize}
\item David Tutor's Untitled ~\citeyearpar{tudor1996twfle},
Toneburst ~\citeyearpar{tudor2004lem}, and
Pulsers ~\citeyearpar{tudor1996twfle}
\item Gordon Mumma's Hornpipe~\citeyearpar{mumma2002lem}
\end{itemize}
\item \textbf{Amplification}
\begin{itemize}
\item John Cage's Cartridge Music~\citeyearpar{cage2013cm}
\item Stockhausen's
Mikrophonie~\citeyearpar{stockhausen1995mmt}
\end{itemize}
\end{enumerate}
\section{Areas of Interest}
The areas that will be explored in detail in this essay include:
\begin{enumerate}
\item \textbf{Types of amplification and feedback}\\
This will discuss the different variations of the techniques based
on the development of technology and the implications of these
variations.
\begin{enumerate}[label*=\arabic*.]
\item \textbf{Analog feedback}\\
Referring to the use of a microphone and loudspeaker to
generate an amplified feedback loop of sounds in the cross-over
field between the two.~\parencite[p.185]{holmes2012eaem}
\item \textbf{Tape feedback}\\
Referring to the technique of recording input to a tape and
looping over a playhead to produce repetitions in the output
signal. Used by Robert Ashley in "The
Wolfman".~\parencite[p.186]{holmes2012eaem}
\item \textbf{Electronic feedback}\\
An alternative to tape feedback which works entirely
electronically, where a signal is ``generated within an
electronic instrument whose design enables the recirculation of
a signal within a closed circuit''.
~\parencite[p.187]{holmes2012eaem} This technique features heavily
in David Tudor's works.
~\parencite{tudor1996twfle, tudor2004lem}
\item \textbf{Feedback manipulation}\\
The delay in time between a direct signal and a feedback signal
allows for the manipulation of repetitions. This gives scope
for a wide range of possible manipulations to the overall
output and is explored in pieces such as Gordon Mumma's
``Hornpipe''. ~\parencite[p.390]{holmes2012eaem}
\item \textbf{Digital feedback}\\
With the growing use of computers for musical processing,
feedback is possible in the digital domain, as it is in the
analog domain. This allows DSP techniques to be applied to
feedback loops leading to significant advancements in effects
such as artificial reverb, giving even further scope to the
possibilities for composers.
\item \textbf{Artificial Amplification}\\
Amplification is an important part of any feedback system as it
allows for control over both initial input and the feedback
loop. It also allows for ``small
sounds''~\parencite[p.6]{cage2011silence} to perceived at much
higher volumes than they naturally occur. This is explored in
John Cage's ``Cartridge Music'' and Robert Ashley's ``The
Wolfman''.
\end{enumerate}
\item \textbf{Reasons for interest in these techniques}
\begin{enumerate}[label*=\arabic*.]
\item \textbf{Indeterminacy}\\
Due to the ``exponentially complex patterns of information flow
in feedback networks''~\parencite[p.11]{weisert2010ioi},
feedback adds an element of indeterminacy to composition. The
build up of audio on each repetition causes varying and often
unpredictable effects in the output
sound.~\parencite[p.100]{nyman1999em} This will be compared to
other techniques for introducing indeterminacy (such as John
Cage's use of the I Ching).
\item \textbf{Rhythmic/Temporal implications of feedback}\\
Feedback allows for the repetition of a sound source over an
extended period of time. This has implications rhythmically that
can be controlled by the composer. The level of signal feedback
will determine the decay and repetition of a signal and can
create infinite loops of a single source sound. The
implications of this will be discussed with reference to
compositions such as Alvin Lucier's ``I am sitting in a
room''.~\parencite[p.57-59, 64-68]{weisert2010ioi}
\item \textbf{Dynamic implications of artificial amplitude
adjustment}\\
Both directly and as part of a feedback system, artificial
amplification will change the perceived level of the input
sound. This allows composers to artificially boost or attenuate
sound in compositions and, in conjunction with a feedback loop,
control feedback decay. This will be discussed with reference
to many of the compositions discussed above (this is used to
varying degrees across practically all previously discussed
compositions.)
\end{enumerate}
\item \textbf{Forms of control}
\begin{enumerate}[label*=\arabic*.]
\item \textbf{Process and systems}\\
Due to it's unpredictable nature, feedback can be difficult to
control and can produce unexpected results. Composers have used
a variety of methods to structure and control feedback as part
of their compositions.~\parencite{weisert2010ioi} These
processes will be explored to understand the different methods
for structuring compositions when composing using feedback.
\end{enumerate}
\end{enumerate}
\section{Potential Issues}
The area of feedback in experimental music has a greater depth than
initially anticipated (as does amplification). This essay may focus more
heavily on feedback than amplification although both will be discussed as
they are intrinsically linked. This may need more thought when planning the
essay.\\
Further refinement of areas may also be needed to focus on the most
important aspects of the subject. This will become clear through writing
the first draft.
\printbibliography
\end{document}
Experimental_Music_Assignment_2/proposal/Notes_for_essay.txt
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Notes for Essay:
Systems:
- Use of electronics for the creation of "systems":
why this is interesting for composers?
The use of "sonification" in computer music allows for the bypassing of
symbolic musical notation, instead opting to drive musical events
through use of other data types (such as arbritrary weather information
for example)
This allows composers to distance there own discourse from the creation
of music, relinquishing control to the data to greater degrees than is
easily acheiveable through acoustic music.~\cite[p.129]{mclaughlin2011dsma}
- Not bound by the limitations of human performance or the timbres of
traditional instruments~\cite[p.351]{holmes2012eaem}
Hud_masters_proposal/Sam_Perry-Research_masters_proposal.tex
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