Sound Ecology: environmental and health factors affecting your hi-fi equipment, your listening, and the planet

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In this article, we examine some environmental and health factors affecting your hi-fi equipment, your listening, and the planet.

Properly executed music reproduction is among the least environmentally harmful of late-20th-century activities, but, like all technological processes, the real costs are hidden. Hi-fi systems are the children of electricity, but unfortunately there is as yet no working method of power generation on the scale presently needed that is wholly “ecological”. Until (and even if) nuclear fusion, geothermal, or some other truly radical scheme proves feasible, it is imperative to reduce electricity consumption and the consequent pollution to levels the planet can comfortably absorb. Every watt counts.

As an equipment designer, I would like to see preamplifiers and the like using batteries so they can be isolated from the increasingly polluted mains supply, but the ecological cost is too great. Perhaps surprisingly, using mains electricity is ecologically less costly than using batteries when the manufacturing and disposal costs of the latter are factored in. In the future, it seems inevitable that portable audio and other equipment will employ bio logical batteries, which can be composted when used. Until then, recharge able NiCad cells are the best option, but a poor one unless old cells are recycled.


Throughout our industrial world, the air is broadly poisoned. In and around any city, and downwind from fossil-fuel power plants, the air is likely to be acidic. The acidity is slight measured in parts per million, but in time it’s enough to visibly and irretrievably corrode or tarnish exposed copper, silver, and tin/lead and nickel conductors and surfaces, including printed circuit board tracks. As the high-frequency elements of audio signals prop agate through the skin of the conductor, corrosion needn’t be very deep to affect sonics. Having a closely related but more reactive atomic structure, copper and silver both have the special property of readily forming arbitrary “complexes” with reactive chemicals. Their labyrinthine structures exhibit nested self-similarity (i.e., fractals), and the result is likely to be a semi conductor, giving rise to semi-diodic (nonlinear) conduction. Gold isn’t bothered so much by inorganic acids from burning coal, but may succumb to organic poisoning from general pollution as well as outgassing plastics.

Many plastic materials contain volatile “plasticizers,” organic chemicals which “outgas” (seep out) throughout the material’s lifespan. PVC, PVA, polystyrene polycarbonate (the material CDs are made from), and any plastics which emulate rubber are the most significant out-gassers. Most plasticizers and may include such arch-toxins as formaldehyde and poly-chlorinated bi-phenyls (PCBs). In city air, high concentrations of ozone; a highly reactive form of oxygen, may catalyze or encourage outgassing, as well as lead to rapid micro-corrosion of freshly wiped switch surfaces.

For most environments, unless all the conductors in your system are sealed by inert means, progressive sonic deterioration will be inevitable. For the most part, modern printed circuit board tracks are protected by the etch resist, a green or blue “ink,” but the solder pads where the component legs are attached are usually bare. With interconnects, there is scant warning about the temporary nature of that pricey “nine nines” purity, many cables apparently being sheathed in highly out-gassy plastics. To accept cables as consumables means wasting noble metals and more energy (and personal!) expenditure on replacements.

I put this matter to A.J. van den Hul, who suggests injecting silicone oil into the ends of your cables with a syringe. But this will work only if you can force the oil throughout the cable length, or if the insulating sheath is perfectly inert and anaerobically bonded to the conductor beyond the ends. Silicone is stable stuff, but not always rosy. In furniture polish, it’s a hazard to switches and contacts. When dispersed in aerosols, silicone molecules can reach unexpected places, spreading out to form thin but potent insulating films, reducing the contact area of any switch or connector which isn’t strongly wiped. If you value your hi-fi ’s reliability, you should stick to traditional solid beeswax polish. Meanwhile, the long-term effects of the increasingly diverse cocktail of urban air pollution on tapes’ binders have yet to be documented.

Ions in the air can influence mood and perception. For the most part, ions are formed by friction; eg, by clouds rubbing, by winds sweeping over deserts and mountain rock, and by waterfalls and fountains. Negative ions, which consist of a gas molecule to which has been attached one or more extra electrons, are beneficial to respiratory systems; many people feel exhilarated when the concentration is high enough. Ionizers are good dust precipitators and need occasional cleaning to work efficiently. Power consumption is minute, but anyone lucky enough to live in a wet, mountainous district can generate negative ions for free by arranging incoming air to pass by falling water.

Positive ions, gas molecules which have been stripped of one or more electrons, are the opposite of beneficial, and are mostly human-made, with treeless areas such as cities and highways probably the worst areas. Seasonal “ill winds” (e.g., the Santa Ana in California, or the Föhn in Central Europe) that drive people to distraction in some parts of the world are natural examples Tobacco smoke, modern air-conditioning (the air brushes against metal and plastic instead of brick and stone), synthetic clothes and carpets, and nichrome elements are common sources of positive ions. The wirewound resistors used in hi-fi amplifiers, power supplies, and passive crossovers consist of nichrome or similar alloys. If unsealed and running warm, these will add to the concentration of positive ions in your listening room.

Ionizers can be used to add negative ions to the air, as well as to cancel positive ones. An ionizer’s effect is necessarily subtle: if you try to produce too many ions (using a higher voltage), counterproductive, toxic ozone is also generated. Ozone is also generated by defective high—voltage connections to cathode-ray tubes; le, conventional (not LCD) TV, video, computer monitors, and oscilloscope screens. The telltale sign is a dim blue glow, visible ‘round the back in the dark.

In pursuit of air-supply purity, I would avoid “hi-tech” air fresheners. Many release toxic organic chemicals into your room, while some just depress your sense of smell. Plants are the planet’s natural air purifiers and conditioners. All release pure oxygen, and many absorb specific toxins. No electricity or replacement filters are needed, but it would be helpful if biologist readers would identify some high-performance house plants for Stereophile readers’ listening rooms. The ubiquitous Spider Plant is reputed to be one. (Your spouse’s birthday present can thus have a benign ulterior motive.)


The word “radiation” carries connotations of radioactivity in most peoples’ minds. In this connection, the word is something of a misnomer dating back to 19th—century misconceptions, as many radioactive materials (e.g., those used in smoke detectors) only emit charged particles (electrons or helium nuclei); there is no electromagnetic (E/M) “field” involved. Radioactivity may, however, involve “ionizing radiation’ principally gamma rays, very high-energy electromagnetic fields at the highest-frequency end of the spectrum that includes radio, microwaves, heat, and light. Excepting those unlucky areas of the planet adjacent to nuclear plants, military bases, and weapons testing and dumping zones, the other, lower-frequency, non- ionizing kinds of E/M radiation are far more pervasive. Radio masts, radar, microwave ovens, cordless phones, and any kind of electrical wiring carrying AC (including music and digital signals) radiate E/M fields.

Until recently, it was held that E/M fields were only harmful at radio frequencies, and then only if they caused actual heating of the body, like a micro wave oven Today, there is increasing evidence that even low-frequency (50/60Hz AC mains) E/M fields can be harmful if they’re powerful enough, particularly if you stay still in them (e.g., while sleeping) and receive the dose over many years7 The main causes for concern are: 1) power distribution adjacent to your house, either 115V/240V (or 220V/440V 3-phase) wires under the pavement or on overhead lines; 2) transformers within 50 yards or so; or 3) much-higher-voltage transmission lines on nearby pylons. The operative factor is magnetic field strength, hence current. To be of concern, this has to range into the tens and thousands of amperes, depending on proximity. Because North American mains supplies are less than half the UK’s 240V, field exposure in amps-per-meter for any given power consumption is, pro-rata, greater, due to the doubled current.

In a US listening room, above a kilowatt of electric heating (8.7A at 115V) is the most likely cause of enough current to significantly increase your exposure—unless you time it to turn off at the times when the room is occupied. The current drawn by most other appliances (including your hi-fi system) is generally an order of magnitude less, and thus far can be considered harmless. However, if the main, incoming AC feeder to your home passes alongside the listening room, the field may be strong, being the sum of all the house current. If this happens, it may be seen as an incentive to cut consumption! If not, and if the wiring can’t be rerouted, you may want to look at attenuating the magnetic field with an intervening 1 steel plate It need not be earthed, but can be, and should be galvanized for longevity. Fields from wiring within and around the listening room can be attenuated five- to tenfold by installing mutually twisted live and neutral conductors. These aren’t readily available, but a qualified electrician can twist individual conductors on the spot. Reducing 50/60Hz field strengths has an obvious benefit to audio. If you are able to use unshielded interconnects at line- or even phono-level without perceptible hum, it’s a good sign that E/M field strengths are biologically negligible in your room.


“Human beings have evolved over millennia to live in a certain physical. . . environment. The rapid technological changes of the past century have put us in a vulnerable position, because physically we are no different from early hunter gatherers”. —Karen Christeansen, Home Ecology

The highest form of heating is an open wood (or peat or coal) fire, because its combined visual and audio (and, with wood or peat, olfactory) stimuli resonate deep in every human mind, down half a million years. This indulgence is closely followed by a cast—iron stove with a transparent mica window. Sure, an open fire vents harmful greenhouse gases, but the heat con version is arguably no less efficient than generating electricity with the same fuel, transmitting it, then converting it to heat. Traditional gas heating is a poor relation, but the more modern, open—flame type shares a little of the wood fire’s perceptual resonances.

Central heating is unnatural, an anodyne uncoupling the psyche from diurnal and seasonal temperature fluctuations, but transparent and safe if it involves heat radiated from hot water and some natural method of humidification. Central heating employing underfloor electric elements carries the dangers of 50/60Hz E/M radiation. You may also want to avoid electrical heating with a bare nichrome element (generally fan- and space- heaters), as nichrome generates positive ions. Oil—filled electric radiators are preferable. As for electronic equipment, it’s not much bothered, even by the kinds of temperatures that zap humans. Don’t forget, though, that gas heating humidifies, which is good for us, but that cyclic humidity speeds corrosion on metal surfaces, while coal and wood fires have occasional fits, and the resulting smoke may settle on your CD's laser. If you live in an urban area, this may happen anyway, without any fires. If the dirt is just wood, coal, or diesel soot, it can be shifted with a blast of clean compressed air.


In the home; conventional fluorescent tubes save resources only if used fairly continuously. You cannot easily dim them, and if you switch them on and off to save energy, tube life is slashed, adding to the rate at which precious metals and toxic fluorescent chemicals are consigned to the dump. This effectively wastes energy-it takes energy to make new tubes. Fluorescents also pollute the mains supply (unless you fit RFI filtering inside the casings), and the twice-mains-frequency flicker rate makes many people feel ill at ease. More "hi-tech" fluorescent lamps are smaller, more efficient, and, using electronic oscillators, flicker at high audio frequencies. The rate isn't a problem to us, but are your CD player's optics 100% secure from this interference? Presently, when the fluorescent tube expires, the integral oscillator electronics go in the trash with it, even though, with competent design, the circuit should last 10 to 20 years.

Plain incandescent lamps neither flicker nor pollute the power supply, and suffer much less stress when switched on and off regularly. Their lifespans can be vastly increased by fitting surge-limiting negative temperature coefficient (ntc) thermistors in-line. For each 100W lamp, I use a $1.50 part with a 120 ohm cold resistance. After a few seconds, it warms, letting full power through, while initially protecting the filament from thermal shock.

Incandescent lamps may be less efficient, but at least the waste is plain heat. Too much heat usually comes hand in hand with sunlight, so if your home makes proper use of daylight, you need only use lamps at night, when their heat output may well be useful. Most listening goes on at night; in most of the hot parts of the industrialized world night is cooler than day, enough for a little heating not to go amiss. Ergo, with sensible use, in candescent bulbs can be 100% efficient (unless you turn up your air-conditioning to compensate for their waste heat production).

Dimming incandescent lamps saves energy and is aesthetically pleasing, but the high-frequency content of the chopped waveform pollutes the mains supply unless really wasteful, heat-generating resistive dimming is used. Well-designed audio equipment shouldn't be affected by dimmers, but why do you have that mains conditioner? So use dimmers with caution; it will help to revise your supply wiring. Sensitive listeners may like to experiment with blue-lacquered "daylight" bulbs, which give a color temperature close to that of mountain sunlight.


There is accelerating pressure to save archives of all kinds. Most of the music, poetry, drama, literature; technical knowledge, and history written or printed on paper made after ca 1870 is doomed because the paper is acidic. After 30—100 years, such paper becomes brittle and turns to dust. Books printed over 300 years ago remain in better condition than ten-year-old paperbacks. Similarly, nitrate photographic film (pre-1930) and recording tapes have a surprisingly limited lifespan, although only analog tapes are yet old enough for this to sink in. Some readers will be aware that many irreplaceable master tapes made in the early ‘70s are now unplayable or close to death. [12, 13]

The push to create new recording/replay formats willy-nilly is dangerous for this reason alone; let alone a new deluge of plastic to outgas away in your home. Claims that some CDs may be unplayable in under a decade are worrying enough. Worse, and unlike vinyl, the polycarbonate from which they’re pressed is not readily recycled. The record industry may be guilty of releasing a lot of rubbish, but at least unsold vinyl was reused ad infinitum. Ironically, and aside from printing and writing on high-quality, acid-free paper, the vinyl disc is one of the few forms of archiving which also stands a high chance of lasting over a century outside of an energy-intensive cryogenic casket:’ After nine years’ hard labor working on improving CD reproduction, I must confess that the vinylphiles have the high ground; the ecological imperative is poised to pull the rug.

As an audiophile, you may feel proud of your minimum signal path but guilty about the electricity bills created by your class-A amplifier. Consider: In the ‘70s, high-end audio could easily have gone another way, into using more and more components—equalizers, surround-sound processors, multi-channel amplifiers—each contributing its share of consumption in manufacture and use.

Ecological crises can be depressing; the sounding of positive notes is essential, therefore. One of these is that the same electronics used for audio have a fundamental role to play in controlling and fine-tuning energy consumption. A primary reason why technology is increasingly seen to backfire is that it has been largely applied in a brute-force way. There are no magic bullets, but electronics have great potential for subtly manipulating universal energies. The component parts may take a great deal of energy to make, but the volume of materials used can be minute, and, properly designed, modern equipment has a lifespan in excess of 50 years. The manner in which electronic engineering can be used to get fine results in audio can be a valuable role model for ecologically sensitive engineering in every field.


• Karen Christiansen, Home Ecology, Arlington ( UK), 1989.

• Debra Dadd, The Nontoxic Home, Tarcher (US), 1986.

• Ole Wik, Wood Stoves, Alaska Northwest Publishing (US), 1977.

• George Waldbott, Health Effects of Environmental Pollutants, C.V. Mosby Co. (US), Second Edition, 1978.

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1. Atoms in the air which are electrically charged, rather than in their normal, neutral state.

2. Did you know that passive, convective air conditioning, provided by tall chimneys opening onto every floor, was perfected in India a millennium ago? Pump water to the building’s top, let it cascade down, and you have aerated water, negative ions, and air conditioning, all with minimal electricity consumption.

3. For “negative” ions to be good is counter-intuitive; some inevitable confusion would have been avoided if electrical polarity had been relabeled the “right” way ‘round when the fundamental unit of charge, the electron, was designated as being “negative” over a century ago.

4. Ozone produced at the earth’s surface does nothing immediate to ameliorate the “ozone hole” Instead, it does a great deal of damage, as a bio-toxin and greenhouse gas, and may take along time to reach the ozone layer, if ever.

5. The tag “ionizing” means they don’t just gently ionize the air, but strip particles off all matter, including the cells in our bodies. The resultant free radicals lead to genetic damage, cancer, and death.

6. In the 1950s, a relative worked on one of the world’s most powerful radars at a Royal Air Force installation in Malaya. A favorite if unofficial test procedure was to direct a microsecond burst from the radiating dish toward a patch of the neatly mown grass by the runway and watch it burn to a cinder.

7. Simon Best & Roger Coghill, “The Killing Fields: the Epidemiological & Biophysical Evidence,” Electronics+ Wireless World, February 1990.

8. Generally 11kv up to 256kV in the UK’s “Supergrid.”

9 They will flicker randomly with mains-voltage fluctuation, but this is not so disturbing, and is also a positive warning that power conditioning is needed.

10 Ben Duncan, "The Mains Issue" Hi-Fi News & Record Review, December 1991.

11 Barry Fox, “Tape Life—An Era of Concern" Studio Sound, December 1990.

12 Barry Fox, “Sticky Tape Developments,” Studio Sound, May 1991.

13 Doug Sax has been more specific, pointing out that the metal-plated mothers from which the LP stampers are grown have an effectively infinite lifetime.

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Updated: Friday, 2015-05-08 18:46 PST