Introduction to Good Sound Quality

If you are interested in good sound quality, this article aspires to help. My thanks must go to the outside assistance given by four professional designers and reviewers who have contributed and proof read the ideas included. This was necessary in a subject which can be confusing for a number of reasons which will become clear as you read.

At face value, good sound quality seems like an easy thing to evaluate. We say things such as:

“I know what I like”

“My system sounds great”

“This item got a great review on sound quality”

“It’s either right or it’s wrong”

Most people want a system which gives you the feeling of “being there” at the original performance – of hearing the singers and instruments as if they were right there in the room in front of you. In the process of both hearing and conducting many equipment auditions I have found that what seems simple is far from it! 

Origin Live has won around twenty “product of the year” awards for their designs. This article seeks to pass on and distill over three decades of professional listening experience into easy to understand concepts:

1. 1. Things to watch out for when evaluating sound quality
   2. Knowing how people listen differently
   3. How to figure out your priorities in sound quality
   4. How reviews and recommendations may come from particular standpoints

I often discuss with clients how they wish to upgrade the equipment in their audio system. Many have great systems which they are happy with but are also aware that they have heard better.  This leads to interesting conversations involving the pros and cons of various options. One of the most common difficulties expressed is that the range of choice is massive and pretty much everything is recommended by one source or another.

There are many stories of clients trying different items of equipment in an effort to address a particular shortcoming in sound quality. For example in a search for more detail in the sound, you may have purchased a pair of speakers, thinking they had great clarity in the audition. However, after a while you recognise that there is no bass warmth and listening becomes a fatiguing experience – tonally these speakers have too much treble. So you duly acquire another pair of speakers without such an “insightful” treble – these are OK for a while but eventually you notice that the sound is not very exciting or involving. If truth be told, it’s boring because the dynamics are poor!  This story is the syndrome of swapping one set of problems for another. All part of the learning curve in achieving good sound quality. Whilst this may be fun for some, it is often too expensive and time consuming for others.

You can usually recognize good sound quality instantly. However it’s prudent to go further than initial impressions as there are many common pitfalls which need to be avoided. If you are relatively new to Hi Fi you may find it  challenging to describe in detail what you are hearing. It’s like learning about computers or smartphones – flashy looking products can have underlying issues, and there are  unfamiliar words and ways of describing the things which are not always consistent.

Why You Need to Evaluate Products to Your Own Satisfaction

Businesses are told by skilful marketing companies that it’s not about the product, it’s about the marketing! There is a lot of truth in this. Just because something is popular and marketed well does not mean it’s the best product out there. Putting claims to the test yourself through audition is the only way of knowing whether something really lives up to the hype. Opportunities to audition equipment may occur at a dealer, hearing a friend’s system, Hi Fi shows or products ordered on a money back guarantee. When these opportunities occur, it is extremely helpful to be on the lookout for key aspects of sound quality and know why they are important. 

Remarks on listening to Hi FI

I used to think that unless someone had severe hearing loss, most people had similar hearing. I put down variations in the way people respond in listening tests as a matter of experience. When new to Hi Fi, I myself used to find comparison tests of different systems quite demanding in terms of always understanding people’s comments. This was usually because I was particularly focused on one aspect of the music. Over time I have learned to tune in to things in a more holistic way rather than just being focused on certain aspects of the music.

Hearing varies from person to person in the same way that some have 20/20 vision, others are short sighted, others long sighted etc. It’s estimated that only 1 in 10,000 people have absolute pitch perfect hearing (meaning you can tell what key is played without a reference note). More commonly 1 in 50 have relative pitch perfect hearing (meaning you can tell whate
ver key is played relative to a reference Key played). 1 in 50 are tone deaf so everyone else is somewhere on the spectrum in between.

These facts tell you that designers, reviewers and listeners vary in their ability to hear tonal correctness. Some will pay a lot of attention to tonal quality and others will value different characteristics. Technical measurements are of value but have limitations when assessing sound quality for reasons that have been well documented over the years. 

People have differing preferences in what they like to hear in music. If you are not used to hearing live music (un-amplified), you might not be so aware of how things should sound. It’s then easy to simply accept mediocre sound quality. We quickly get used to the sound of our system without realising how much it can be improved. When you listen to a piece of familiar music on a different system, it can often shed a different light on things. It takes time, experience, and critical listening to improve how you identify what makes good sound. Reading reviews or listening to sales people doesn’t guarantee you will end up with the best solutions.

I for one, have made many seriously poor buying decisions by listening to the enthusiastic opinion of others before listening for myself. So when reading reviews or listening to recommendations it helps to have a charted map of what great sound quality really consists of. 

Three Main Categories in Good Sound Quality

At Origin Live we find that the elements which make up good sound quality mostly fall into 3 core categories: Clarity, Dynamics and Tonality. What follows is not necessarily the most perfect way of looking at things but it helps to simplify and clarify a complex subject.

The Winning Combination for Good Sound Quality

It is surprising how you can demonstrate 2 systems to a room full of listeners and there will be different opinions as to which is best. You can then carry out a similar demonstration between 2 other systems and the room will be unanimous on the winner.

The most likely reason for this is that in the first instance, one system appealed only to listeners with a given preference for clarity (by way of example) whereas in the unanimous verdict, one system appealed to all types of listener. This can be illustrated in the diagram below where you can see the sweet spot of truly good sound quality.

“Best Sound” which finds Universal Acceptance

An evaluation of good sound quality will not only look at individual aspects in the music but also appreciate things holistically.

One way to do this is to score the above diagram. The intersection of the 3 circles in area CDT represents the overall score. The perfect sound is one which would score 100% in all three categories. The score at intersection “CDT” would be averaged to  100%      [100C + 100D + 100T]/3 = 100%.  Where C is Clarity, D is Dynamics & T is Tonality

The value of seeing the individual scores 100C 100D 100T – is that you may have a particular preference for clarity (for example), and not care too much about tonality. So if the score was [100C + 100D + 30T] / 3 = 77% you would be happy and the system may come at much less cost.

Of course no such scoring system has been formalised but it gives a concept of how reviews on good sound quality could score things to arrive at their conclusions.

It is interesting to note that the quality of Clarity/ Dynamics/Tonality can be enhanced or diminished by every component in your system – from source to loudspeakers.

Basis of Observations

In 35 years carrying out listening tests, hearing demonstrations, giving demonstrations and sitting on professional blind test listening panels, it’s very clear that an understanding of what people like and why, is of supreme importance. This understanding helps avoid a myriad of pitfalls which may occur in:-

Design. Evaluation, Reviews, Your Choices etc.

Observations on Preferences

Everybody, even reviewers focus on different things when listening to music. Just as people prefer different genres of music, so we have particular preferences on aspects of what we consider to be good sound quality. Different aspects of sound draw different people in.

A  parallel to what people like in good sound quality, is the type of books or films people like. Genres such as thriller, detective, romantic etc, all have their equivalents in music and equipment sound. Some people are more analytic in their listening and looking for the fine details in playback. Others are looking for the thrill you get with quality dynamics. Some most enjoy great tonality and the pleasing effect on the ear of wonderful harmonics in the music. The all round listener will latch onto all three of these while listening to music.

If you  are not particularly sensitive to tonality, you will probably pay a lot more attention to things like dynamics or clarity. If on the other hand, you are sensitive to pitch and harmonics (e.g like a musician) then you may find tonal anomalies extremely irritating and will not rate equipment which is poor tonally. Tonal anomalies can include things like singers sounding flat, piano harmonics sounding unnatural etc. Knowing what you like in good sound quality is an important key to making the best equipment choices.

Magazine reviews are often very helpful in shortlisting products for audition as they often discuss sound quality in depth. However it’s worth recognising the following:

1. 1. A huge number of products all receive the same rating (number of stars or % score etc)
   2. Scoring systems don’t rate absolute performance of products. For example a £200 product will get 5 stars which means that it’s good in it’s class. What this score does not tell you, is how it compares to a £1000 product. The truth is that there are products which outperform others at over 10 times the price.
   3.  It’s natural that any review will be coloured by the reviewers hearing and personal tastes. Ignoring the overall rating, good reviews still give a picture of a product’s characteristics which helps.

Food for Thought on Good Sound Quality

Hopefully this article has provided food for thought in what makes good sound quality from a subjective point of view. This is a huge subject of course but sometimes new ways of looking at things can provide all sorts of breakthroughs.

A reviewer recently commented to me with his usual insight, on an amplifier with a class-D power supply. The story went like this “I was impressed for the first half-hour, the sound was so clean and I thought I was onto something. After half an hour, I don’t know why, but the music just became boring and clinical – it just didn’t sound like real music.”

There are a number of explanations for this syndrome. One probable reason has to do with something often ignored or misundertood – Harmonics – these are so influential on music and also highly complex.

For example, my son recently wanted to upgrade his violin. The violin specialist related that the sound produced by a good violin will carry all the way to the back of a large concert hall whereas an inferior violin is absolutely incapable of such a feat.

The explanation given was that the overtones (harmonics) of the better violin interact with the primary notes to propagate them better through air. It’s a bit like sprinting – your legs do all the carrying but try not swinging your arms or swinging them in the opposite direction to normal. Harmonics may well be what arm swinging is to running. This is obviously a simplistic illustration but should give pause for thought.

If harmonics help sound waves travel in the air, it’s not much of a stretch to surmise that they affect electrical waves travelling in wires. Normally the sonic differences between wires are explained in terms of skin effect (the tendency for the current to flow down the outside of the wire) but this is doubtful as it only occurs at very high frequencies outside the audio bandwidth (intermodulation effects, in this case, are of a very low order).

Other explanations of sonic differences in cables include the fact that the impedance value (resistance) of any wire varies at different frequencies.  This means it handles low frequencies differently from high frequencies. This is certainly true but not the whole story.

How do you think of electrical energy travel? 

Harmonics within the signal create complexity that will be handled better by some wires than others. To think of electricity as the simple flow of electrons down a wire is a huge mistake. Electrical energy flows at approximately 1/3rd the speed of light in copper. However there are serious theories that electrons do not actually flow at all – others say they move at about 4 miles per hour. 

The flow of electricity is more like an electromagnetic pulse wave than the flow of electrons from A to B. Once you start thinking in terms of electromagnetic waves, it’s easy to see why harmonics play such an important role. Either way, there are aspects of the sonic signature of different wires that fall well outside layman explanations. 

Sonic Signatures in materials and structures 

Everything in Hi-Fi is affected by good harmonics, poor harmonics or lack of them. Harmonics are either helped or hindered by the design of a cable due to electromagnetic field interaction within the current carrier. The same principle applies to the mechanical vibration of components. You want to eliminate false harmonics (harmonic distortion) but keep the original harmonics of the music intact. Harmonics explain many of the puzzling aspects of why materials have a sonic signature.

Switching the conversation back to electrical harmonics – Why does Silver wire usually have such an open, clean sound, with brilliantly lit upper mid-band and treble but seldom goes deep in the bass? Some have suggested that this has nothing to do with its 1.05 times better conduction, but much more to do with its grain structure and electromagnetic characteristics.

Listening to music is one of life’s great pleasures. Close to our sense of smell, music has the strongest power to evoke mood changes and bring back memories. We have all had the experience of hearing a song we loved in our youth. Immediately, we may think of a first love, a holiday or special event, friends we knew and experiences we haven’t remembered in years.

Listening to music actually causes the brain to release dopamine, the “feel good” hormone that restores logic and enables us to focus and concentrate. This can literally change your life. For example upbeat, high tempo songs raise energy levels if you feel lethargic. Classical music or jazz will often help you unwind properly after a busy day. It is interesting that when Dame Kelly Holmes won Olympic gold in the 800m and 1500m, she had a theme song in her head for the training and events. Where would films be without music to capture the mood so much better?

Why have great sound quality?

The actual quality of sound reproduction can have a very strong influence on our enjoyment of music. Why is this though? Surely if you can identify the song it’s good enough? Ultimately the answer to this lies in defining what exactly is “better” sound quality? To be clear about this, leads to understanding the issues and making correct choices.

What is Great sound quality?

The ear and brain enjoy particular aspects of music. The order of priority is different from person to person but all of the following are present in a great system.

Dynamics: The ability to reproduce the full energy of a note without loss of impact. Loss of dynamics are usually manifested by an artificial softening of bass notes, lack of speed, blurred treble etc. The sound is essentially dull and boring in comparison with a dynamic sound. Dynamics are akin to the acceleration and braking performance of a car. You should put a big flag on the fact that measurements of dynamics are never included in loudspeaker specifications! This is not to be confused with dynamic range which simply states the range of frequencies that a speaker produces. Neither are efficiency / sensitivity figures a proper measure of dynamics.

Timing / musicality: Live music is coherent, liquid and integrated – For example, the bass does not lag behind due to sluggish speed or overhang.

Tonal balance: Too much treble emphasis soon causes listening fatigue. Conversely a bass oriented sound will become heavy and oppressive.

Separation / clarity / definition / transparency: This creates interest as it enables you to “see” into the mix and latch onto each individual strand of the music, whether it be vocals, drum beat, keyboard etc.

Natural Sound: The ear does not like distortion introduced by resonance, electronics or phase issues.

Freedom from Coloration: Cabinet resonance, cone breakup and ringing are often present in loudspeakers. These are a bit like artificial additives in food and detract from music by causing distraction, usually at a subliminal level but there nonetheless.

Ability to create an “out of the box” 3 dimensional sound image: This is really a result of good definition and tonal balance because if these are present you are halfway there, but imaging is also related to cabinet shape and driver dispersion.

Because the brain knows what it likes and expects to hear from music, it is constantly “filling in the gaps” for reality. In other words it imagines it is hearing the real thing. This is a form of “error correction” that is going on all the time. Visual cues sometimes make this easier. For example one of our staff was at an exhibition and noticed that watching a video of a singer and band as it was played through a reasonable system made the effect much more real. As soon as he closed his eyes the flaws of the music reproduction were immediately apparent. Closing your eyes is not something we recommend but the point here is that the brain fills in for reality.

There is one caveat here and it is a big one. The error correction process that goes on, is work for the brain that it prefers not to do. Eventually it gets tired and your level of enjoyment does not last anywhere near as long as it would with a better system.

Next article we will look at the challenges that must be overcome in order to progress the art of speaker performance.

This article is prompted from talking to some of our clients, who are concerned that because they are not getting any younger, their hearing may be on it’s way out.

I would like to start by saying that 25 years ago, I personally knew an excellent audio reviewer by the name of Peter Turner, who was still reviewing at the age of 80! In case you are wondering if his reviews were reliable, I can say that he would sometimes go round to a much younger friend’s house to get a second opinion. I was with him on one of these occasions and can report that his hearing was as sharp as a pin – we had little to add to his observations during this equipment audition.

A few other factual stories are worth relating before drawing a few conclusions.

On radio 2, there was a phone in discussion regarding the rights and wrongs of 20kHz sirens installed outside city centre bars, to disperse young teenagers. Most adults hear up to 18kHz and are not supposed to be affected by this, whereas the under 15s should find it deafening. The surprising thing was, that there were 40 year old women phoning in to say how painful they found these sirens. This indicates very strongly that they probably retain hearing at 20Khz simply because they have not exposed themselves to much noise.

One of my friends was a sniper in Iraq. At age 23, he experienced severe hearing loss from the regular firing of a rifle with it’s very high impulse levels of sound.

A silver medallist swimmer who was also a real audio enthusiast, related to me that his hearing had been knocked down to around 10 kHz from the constant high frequency noise of rushing water past his ears in the pool. Although he was unable to hear top end detail, he was still able to appreciate even the smallest improvement to his Hi Fi, especially in the bass as this part of his hearing was relatively unaffected.

The star drummer at the opening ceremony of the London Olympics was deaf from birth, and simply “feels” the music from vibration.

Lastly there was a concern a while ago that older orchestra conductors might not be as good as younger ones due to hearing loss. Bear in mind that orchestra conductors suffer hearing loss from standing in front of very high dynamic sound levels. So a test was conducted – It was found that the more experienced older conductors were able to point out things that the younger ones did not pick up. This is explained by the very important way, in which note frequencies and harmonics interact with all the other frequencies (called inter-modulation effects).

The brain is incredibly adapt at interpreting these inter-modulation effects. So although your ear may not hear high frequencies directly (because of hearing loss), the brain interprets the inter-modulation effects to “hear” higher notes which the ear is not physically hearing. The BBC studied this phenomenon and gave the example that even on a phone which only produces sound above say 500Hz, the brain still can identify a deep voice and is “hearing” the voice as producing notes down to say 200 Hz or less. This is the same phenomenon that can trick the brain into thinking small speakers are producing deep bass when they are not.

From these stories, the following suggestions can be made:

• Hearing is the last sense to go and remains better than we may think, right up to the end of our lives.
• Hearing loss is more related to exposure to excessive high frequency noise, than age.
• There is much that we do not know about hearing, one scientific journal was
  reporting that sensors in the eye retina, pick up frequencies far above 20kHz

Hopefully this will go some way to dispersing some of the concerns regarding the validity of experiencing high quality sound as the years pass. In a future article we shall talk about why a small minority of people do not seem to hear the differences that others rave about. Part of this discussion will go through why the ability to hear even minor differences is important and how to succeed in hearing them.