Systems Theory and Audio Feedback
This page introduces systems theory using the classic example of a sound system. However, it goes beyond a simple explanation by exploring what limits amplifying feedback cycles.
This is the amplifying feedback cycle that drives audio feedback. Most people have experienced this feedback, the sudden, piercing screech that occurs when a microphone picks up its own sound and re-amplifies it.
I include this page on systems theory because understanding how feedback works in a simple sound system provides a solid foundation for recognising its operation in more complex systems, including two areas covered by this website: (1) the amplifying feedback cycles that drive problematic behaviour in individuals, and (2) those that drive climate change.
For example, when audio feedback occurs, the sound system can reach its maximum power, amplification ceases, and the volume remains at a constant high level. Unchecked amplifying feedback eventually hits a limit and pauses operation, having transformed the system.
Self-amplifying feedback in a sound system.
Audio feedback occurs when a “self-amplifying feedback cycle” becomes dominant in a sound system.
In this cycle:
- the microphone picks up a resonant pitch, which
- increases the amplifier output at this pitch, which tends to
- increase loudspeaker volume at this pitch, which tends to
- Increase the input volume of this pitch to the microphone.
While this cycle dominates, “the louder it gets, the louder it gets”, but the amplification cannot go on forever.
Feedback cycles show tendencies.
A feedback cycle indicates what tends to happen. Other factors can intervene and break the cycle. For example, “louder loudspeaker volume” only “tends” to produce “louder microphone input”. When someone puts a cover over the loudspeaker, this intervention can break the cycle, and you can get “softer microphone input”, not “louder microphone input”.
The nature of any amplifying feedback cycle
Any amplifying feedback cycle has a circular sequence of causal connections between system attributes, in which an increase in any attribute influences the next, which then influences the next, creating a ripple effect around the cycle until it increases itself, which causes a further ripple around the cycle. In amplifying feedback, an increase in one attribute leads to a further increase in that attribute. (Capra, 1996, p. 56).
- Self-amplifying feedback in a sound system.
- Feedback cycles show tendencies.
- The nature of any amplifying feedback cycle
- Maruyama & his Second Cybernetics
- Capra: Feedback cycles reveal organisation.
- Alternative names for feedback cycles
- Amplifying feedback & other influences
- Inhibiting amplifying feedback
- Reinforcement of amplifying feedback cycles
- Other features of amplifying feedback
- Amplifying feedback & exponential change
- Time delays
- Reversibility
- A self-organising system
- Conclusion
Maruyama & his Second Cybernetics
Maruyama (1968) revolutionised systems theory by focusing on amplifying feedback cycles and their creative nature. He called his theory “the second cybernetics”, in contrast with earlier cybernetics, which focused on the destructive nature of amplifying feedback and mechanistic, damping feedback cycles. According to Maruyama:
- Amplifying feedback cycles are widespread (p. 304).
- Amplifying feedback cycles can disrupt the existing order and create a new order. For example, rock weathering is an amplifying feedback process that is (1) a vicious cycle in that it destroys rock, but also (2) a creative, virtuous cycle in that it creates fertile soil and forests (p. 305).
- These feedback cycles interact and can support or counterbalance one another, producing stability, oscillation, or transformation. (p. 312).
- Amplifying feedback cycles can occur between people and cause problems; for example, two aggressive individuals can easily escalate a misunderstanding into a physical fight.
- These cycles can also occur within a person, causing problems. For example, reduced self-confidence can lead to poor performance, which in turn can further reduce self-confidence (p. 312).
- In psychotherapy, the goal should be to break vicious, damaging feedback cycles underlying the presenting problem and to initiate virtuous feedback cycles that alleviate the problem (p. 312).
Capra: Feedback cycles reveal organisation.
A feedback cycle displays the organisation of the system, as distinct from its physical structure (Capra, 1997, p. 63).
Alternative names for feedback cycles
You can call an amplifying feedback loop a:
- Positive feedback,
- Deviation amplifying mutual causal process (Maruyama)
- Self-amplifying feedback loop,
- Self-reinforcing cycle,
- Vicious cycle, and
- Virtuous cycle
You can call a damping feedback loop a:
- Negative feedback,
- Balancing feedback,
- Stabilising feedback, and
- Deviation counteracting mutual causal process (Maruyama)
Amplifying feedback & other influences
For the systems discussed here, I typically highlight a key amplifying feedback cycle that drives change or problem behaviour. Unfortunately, the amplifying cycle by itself suggests that amplification can continue indefinitely, which defies common sense. A more realistic understanding recognises that every amplifying cycle operates together with other influences—some that reinforce the cycle and others that inhibit it. Recognising these additional influences is essential for understanding the system.
The following table provides an overview of these influences on a considered amplifying feedback cycle.
| Influence | Reinforcing influences | Inhibiting influences |
| The amplifying feedback cycle under consideration. | The amplifying feedback cycle reinforces itself. All amplifying feedback cycles are self-reinforcing. | The amplifying feedback cycle, when unimpeded, eventually exhausts a resource it needs to continue, and pauses, having transformed its system. All amplifying cycles eventually hit a limit. |
| Damping feedback cycles | – | A damping feedback cycle may control the considered amplifying cycle and maintain system stability, opposing the deviation of a variable from its target value. |
| Other amplifying feedback cycles | Other amplifying cycles can reinforce the considered amplifying cycle, forming a group of mutually reinforcing cycles. | Other amplifying cycles can oppose the considered cycle. |
| External events | External events can strengthen the considered amplifying cycle. | External events can disrupt the considered amplifying cycle. |
Inhibiting amplifying feedback
First, consider the things that can inhibit an amplifying feedback cycle.
Inhibitor: A damping feedback cycle.
A damping feedback cycle can control an amplifying feedback cycle. Damping maintains the system’s integrity by reducing the deviation of a system variable from its target value.
Consider the damping feedback cycle that constrains the audio feedback amplifying cycle. It is the sound operator who hears the feedback escalating and adjusts the controls to damp the audio feedback. Here is a diagram of the damping feedback cycle.
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| More Deviation: Excessive Loudspeaker volume Less | More Control: The operator reduces the amplifier’s power. More | |
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In this damping cycle:
- The upper arrows show “more excessive volume” tending to cause “more control”; and
- The lower arrows show “more control”, tending to cause “less excessive volume”.
(You can think of gambling like this: a damping feedback cycle can limit excessive gambling, e.g., the gambler can decide that they have spent too much time or money on gambling and leave a gambling venue.)
The nature of any damping feedback cycle
In general, a damping feedback cycle has a circular sequence of causal connections, as does the sound system damping cycle shown above. The cycle differs from an amplifying feedback cycle because, in a damping cycle, a deviation in one system attribute, such as a boat’s deviation from its target course, triggers a corrective action that reduces that deviation. This is the opposite of amplifying feedback, in which an increase in one system attribute causes a further increase in that attribute.
Here is a diagram of the damping feedback cycle for a sailing boat.
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| More Deviation: The sailing boat heads to the right of the target direction. Less | More Control: The sailor pushes the tiller further to the right. More | |
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Inhibitor: Other feedback cycles
Some amplifying feedback cycles can weaken others.
This concept is useful in counselling because many amplifying feedback cycles drive a client’s presenting problem, like problem gambling. So, identifying and activating an amplifying feedback cycle that weakens these problem-amplifying cycles is the start of recovery.
A simple audio system does not have other feedback cycles, so consider a different example. The amplifying feedback cycle of foxes breeding does inhibit the amplifying feedback cycle of rabbits breeding. Here, three feedback cycles interact.
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| More Rabbit Numbers More | More Rabbit Breeding More | |
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In this rabbit breeding cycle: (1) more rabbits tend to produce (2) more rabbit breeding, which tends to produce (3) more rabbits.
The fox-breeding cycle has precisely the same form as the rabbit-breeding cycle:
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| More Fox Numbers More | More Fox Breeding More | |
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Now, foxes prey on rabbits, as shown in the following cycle.
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| More Fox Numbers Less | Less Rabbit Numbers Less | |
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In this cycle: (1) an increase in fox numbers tends to (2) decrease rabbit numbers, which tends to (3) decrease fox numbers, which tends to (4) increase rabbit numbers, which tends to (5) increase fox numbers.
Mathematical models of predator-prey populations predict that these populations tend to oscillate, and nature reflects this phenomenon. See the Wikipedia entry on the Lotka-Volterra equations.
This example shows that amplifying feedback cycles can interact with one another. The fox breeding cycle does tend to weaken the rabbit breeding cycle, and the interaction is complex.
Inhibitor: Reaching a maximum plateau
Any uncontrolled amplifying feedback cycle will eventually reach a limit because physical quantities, such as the power an amplifier consumes or the volume a loudspeaker emits, cannot increase or decrease indefinitely.
An amplifying feedback cycle can reach the upper limit of one of its components. This can occur in the sound system when the power required to produce a louder sound reaches its upper limit, and the audio feedback volume plateaus at its maximum. Here is a diagram of this self-limiting feedback cycle.
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| “Microphone input volume” increases (1). | Electric power used for amplification increases (2). | |
| The increase in “speaker output volume” drops to zero as the “power used” approaches its maximum (3). | |
In this cycle, (1) an increase in the volume input to the microphone tends to (2) increase the electric power used to amplify the sound, which tends to (3) increase the speaker output volume, but:
- As the power used approaches its maximum, the amount of this increase reduces, and
- When the power used reaches its maximum, the increase in the speaker’s output volume becomes zero, and the screech reaches a constant high volume.
The audio feedback cycle and this self-limiting feedback cycle work together to organise the sound system. This self-limiting cycle reflects the diminishing return of amplification as the power approaches its maximum.
This cycle does not preserve the system; it transforms the system by driving the volume to its upper limit. The venue could not use a sound system with this potential; their audience would have to flee whenever the audio feedback cycle became dominant.
(You can think of gambling reaching an upper limit due to a system limit. For example, when a gambler is betting at the maximum rate that one poker machine can accept bets.)
Inhibitor: Breaking the system
An amplifying feedback cycle can limit itself by escalating until it exhausts a necessary resource or breaks the system, leading to zero activity.
In the sound system, the amplifying cycle can increase the volume of the screech until a component fails, causing it to break and leaving silence.
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| More Loadspeaker Volume Zero: When the stress is too big. | More System Stress More | |
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In this cycle:
- The upper arrow conveys that more “loudspeaker output volume” tends to cause more “system stress”; and
- The lower arrow conveys that more “system stress” tends to cause zero loudspeaker volume when the stress becomes too high, and a component fails.
This cycle resembles a damping feedback cycle, but it is not one, as it does not control deviation away from a target.
(You can think of gambling in this way. When a person does not pause their gambling by themselves, an external limit can pause their gambling, such as (1) running out of cash, (2) ending up in gaol, and (3) the gambling venue closes and ends a marathon gambling period.
Another example is with a global heating feedback cycle that melts Arctic sea ice. This cycle will stop when there is no ice left to melt.
Inhibitor: External events
External events can disrupt an amplifying feedback cycle.
In a sound system, an electrical power failure would disrupt the audio feedback. (This would be an unlikely occurrence.)
For a gambler, many external events can interrupt their gambling, e.g., a hospital stay.
Reinforcement of amplifying feedback cycles
Reinforcement: an amplifying feedback reinforces itself
An amplifying feedback is self-reinforcing. Unimpeded, it transforms its system, destroying the old system and creating a new one.
The audio feedback, if unimpeded, could hit a continuous maximum volume or break the sound system. Both these possibilities are transformations that would leave the event without a usable sound system.
Reinforcement: a group of amplifying feedback cycles
Other amplifying feedback cycles can reinforce the considered amplifying cycle, forming a group of mutually reinforcing cycles.
This occurs in the amplification of problem gambling and global heating, but not in the simpler sound system.
Reinforcement: External events
External events can reinforce an amplifying feedback cycle.
For audio feedback, this reinforcement is not likely. However, for other systems, such as global heating, this is the critical issue. The human burning of fossil fuels, an external influence on the natural climate system, has triggered global warming and poses a risk to life as we know it on planet Earth.
Other features of amplifying feedback
Here are some other features of amplifying feedback cycles that I will consider. An amplifying feedback cycle can:
- Produce exponential change when it meets no resistance.
- Experience time delays.
- Reverse directions
Let’s examine these points in more detail.
Amplifying feedback & exponential change
Once an amplifying feedback cycle becomes dominant and stays so, it will bring exponential change, initially slow and then explosive, until the transformation it initiates reaches a limit and the cycle can go no further.
For example, when a person in a chair leans back past the tipping point, they rotate until they reach the limit of rotation — the floor. The rotational energy does not increase at a constant rate over time. It increases exponentially.
Refer to the “Tipping Point” page on this website.
Time delays
This exponential escalation often does not continue unabated due to the inhibitors of amplifying feedback. These inhibitors include the discussed damping feedback, interaction with other amplifying feedback cycles, reaching limits, and external events. This means that amplifying feedback can often not gather pace. Additionally, some processes are inherently slow, such as melting ice, which requires a large amount of energy.
Sound system design ensures minimal amplification delay so that hearing the performance looks natural. This immediate amplification means that the feedback screech can escalate to an unbearable level within seconds.
The delays occur in other systems:
- For a gambler, life events, such as a hospital admission, can delay an amplifying feedback cycle that drives their problem gambling.
- In global heating, a volcanic eruption could temporarily delay the amplifying heating cycles.
Reversibility
Some amplifying feedback cycles are reversible as they can amplify changes in either direction. For example, the previously discussed interaction between fox and rabbit numbers is reversible.
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| More Fox Numbers Less | Less Rabbit NUmbers Less | |
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In this cycle: (1) an increase in fox numbers tends to (2) decrease rabbit numbers, which tends to (3) decrease fox numbers.
The reverse is also true:
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| Less Fox Numbers More | More Rabbit NUmbers More | |
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In this cycle: (1) decrease fox numbers tends to (2) increase rabbit numbers, which tends to (3) increase fox numbers.
Another example is the current amplification of global heating and the melting of Arctic sea ice. This is currently amplifying global heating, but if cooling were to occur, it could also amplify global cooling.
The amplifying feedback cycle driving the audio feedback screech is irreversible. If a person put their hand over the microphone, reducing the microphone’s input volume, the cycle would not produce further decreases in volume. It would continue to increase the volume.
A self-organising system
Systems that receive a continual input of energy can become self-organising. For example, the sun provides the energy that drives the water cycle with its evaporation, rainfall, and river flow. This energy shapes the character of rivers as people know them, creating the recurring rapids and eddies that consistently appear depending on the water levels (Capra, 1996).
Although I have not elaborated on this here, I propose that the damping and amplifying feedback cycles that organise a person’s life, their actions, feelings and ideas, form a self-organising system that continually shapes a person’s character.
Conclusion
First, I found amplifying feedback cycles useful for understanding and assisting my counselling clients. The cycles help understand what drives a problem. Then I realised that other amplifying cycles were driving global heating – and that systems theory applies to any system. This framework helps me understand the world, including human problem development and recovery.
A more detailed examination of feedback cycle interactions could draw on insights from system dynamics, chaos theory, population dynamics, catastrophe theory, and mathematics.
In summary, here again is the overview of the influences on any considered amplifying feedback cycle.
| Influence | Reinforcing influences | Inhibiting influences |
| The amplifying feedback cycle under consideration. | The amplifying feedback cycle reinforces itself. All amplifying feedback cycles are self-reinforcing. | The amplifying feedback cycle, when unimpeded, eventually exhausts a resource it needs to continue, and pauses, having transformed its system. All amplifying cycles eventually hit a limit. |
| Damping feedback cycles | – | A damping feedback cycle may control the considered amplifying cycle and maintain system stability, opposing the deviation of a variable from its target value. |
| Other amplifying feedback cycles | Other amplifying cycles can reinforce the considered amplifying cycle, forming a group of mutually reinforcing cycles. | Other amplifying cycles can oppose the considered cycle. |
| External events | External events can strengthen the considered amplifying cycle. | External events can disrupt the considered amplifying cycle. |
Amplifying feedback cycles do not exist in isolation; various inhibiting factors can slow or delay the exponential changes they might otherwise produce. Recognising these influences enhances the credibility of systems theory and deepens understanding of amplifying feedback. In turn, this reinforces the argument that such cycles are key drivers of both climate change and human problems.
All the above influences are at work in the life of a problem gambler.
- Introduction to my counselling pages
- References: See the introduction page
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- A counselling session with a cyclic intervention
- Self-reinforcing feedback and human behaviour
- Systems theory and audio feedback
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- Site Map: Links to all pages, including all counselling pages
First loaded Nov 2025. Updated: 22 Dec 2025