The pursuit of “good sound” lies at the core of high-end audio, but what exactly is good sound?  Good sound is a subjective concept, and we each have our personal ideas about it.  However, I’d like to propose a view which identifies two broad levels of sound quality.

What Is Not Bad Is Good

On the first level, sound is considered to be good if it’s free from obvious noise or distortion.  It allows the listener easily to hear and recognise the tune and lyrics of music, and follow movie dialogue without much difficulty.  This is most people’s view, and it reflects a quality level attainable by practically all the devices commonly used for listening, including phones, computers and TVs, as well as consumer audio products.  For these listeners, the sonic deficiencies of these devices, including bandwidth limitations and dynamic constraints, are not generally considered seriously to detract from the sound, and typically do not interfere with their enjoyment of their listening experiences.  Thus, they can select their devices based on considerations such as price, size, portability, brand, colour, visual design and features, rather than sound quality … and they do.  As a result these are the characteristics that differentiate consumer products from one another.

There’s More To It Than That …

There’s a second, higher standard of sound quality.  At this level the absence of gross noise and distortion is taken for granted.  Here the focus is not on tune, lyrics or dialogue intelligibility. These are expected.  This level is about such things as full range sound, without bandwidth limitations, effortless power and reproduction of the full dynamic range, the subtleties and nuances of tone, timbre, vocal inflection, dynamics, imaging, soundstage, pace, rhythm and timing (PRaT), attack, decay and reverberation.  These create a sense of realism in sound, reveal the artistry of performers and convey the full emotional power of movies and performances. This is the realm of critical listening, the domain of the audiophile.

Seekers of this sound quality level select their audio equipment with a clear focus on sound performance.  They set up their systems in their listening rooms to optimise performance, and are mindful of issues of acoustics.  For us, as I include myself in this community, consumer devices are only used for non-critical listening, exploring for new music, and when no better-quality option is available.

A Word About Noise And Distortion

Noise is an unwanted signal which is added to the desired signal, negatively impacting its reception by the listener.  These additions generally have a character, such as 60Hz hum, pops or clicks, that is distinct from the intended sound, and which distinguishes them. Distortion is not so much an addition to the signal, as an undesired alteration of it.  This altered sound typically follows a similar pattern to the original sound, but has a clearly different character, for example the high frequency fuzziness associated with clipping.

The presence of noise and distortion is not always easy to observe directly.  In smaller amounts their effect can be perceived by their ability to mask low-level components of the audio signal.  Important aspects of sound reside in these low-levels.  Consider the following:

• The timbre of an instrument depends on it’s overtone signature, the pattern of higher frequencies, often harmonic multiples, that accompanies the fundamental of each note.  Some of these overtones, though important in terms of revealing the instrumental timbre, may be quite low in level.  If these are masked there is a perceptible change in timbre.
• Spatial perception of sound depends on patterns of difference in the sound reaching the two ears.  These differences can be quite small and easily obscured by noise and distortion.
• The sense of pace and rhythm in sound depends on transients, rapidly changing sounds, such as the percussive beats of drums.  In the presence of noise and distortion the rapid transitions of these transients can become vague and less distinct, affecting the perceived sense of timing in the sound.

As a result, these characteristics which differentiate immersive, engaging, realistic sound from that which is merely recognisable, are victims of noise and distortion.  Their absence is a pointer to the presence of impairments.  If these can be reduced or eliminated, the listener will experience a perceptible and enjoyable improvement in sound quality.

What Do You Think?

Considering the two levels of good sound, we have a way to think about sound quality.  When we don’t hear any obvious impairments, but still find our sound uninvolving and lacking in emotional impact, we have a way to explore and improve the situation.  We also have a way to speak with those unfamiliar with or sceptical of high-end audio, and explain to them what more there is if they just seek it out.

So, what’s your view?  Do you agree with this two-level characterisation of sound quality?  Which category matches your view of good sound?

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