The term, in Hi-Fi circles, is unmistakably equated to the loudness levels that the sound system is capable of – and mistakenly so. Maximum SPL (Sound Pressure Level) as a separate specification actually gives idea about the loudest sound power that the system is capable of.

Dynamic Range – as the term actually suggests is a measure of the difference between feeblest to the loudest that the system can deliver. Since it is presumed that the systems have no problem delivering the lower sound levels, the term should actually be more indicative of the higher levels capable. Sounds logical, and is – admittedly – true for a Mid-Fi system. But is not entirely true for true Hi-Fi system and that added part to make the statement entirely true is very significant!

To understand the significance of this term, let us understand what it translates into our hearing. A system with truly high Dynamic Range is capable stunning the listener with its sudden transience, thus can deliver true surprise in case of uncorrelated sounds or free-form music genres like jazz. In real life, if we (ever get to) hear a live jazz performance in a small club without any amplification or a speaker system in the way then we will be surprised that the music levels being amazingly loud – much louder than the best of the audio systems that we may have in our homes. Bigger surprise will be after a while – though the levels will be ‘very’ loud, you will not have the listening fatigue that you generally have after a long listening session. At home you may try and reach for the remote to tone down the volume levels, but you cannot do that in this club, neither would you need to!

If you have ever experienced a brass band in a marriage procession from the close proximity – the fullness of the sound with its loud but open characteristic is delight to listen, even though most of them do not perform so well!

There is an element that most of the Indian music has missing compared to the western – especially classical. While melody and rhythm are basic tools of expression in both the classical music, there is a third element in western classical – that of loudness as a tool of expression. You may find numerous instances where during a symphony, there are long pieces of very feeble music having vast dark spaces left in the musical landscapes. The system that resolves these near-silent pieces with an aplomb and poise without compressing (making them louder than they actually are) have fantastic low level resolution or superb microdynamics. Now such a system when doesn’t lose its calm and stays in control when getting (really) loud is a system that has great Dynamic Range!

A good test will be a track where there are many instruments playing together at different volume levels and all of them having same contribution in the acoustic landscape as they had when they were playing solo or during quieter times. This is difficult. Feeble instruments usually lose their focus and linearity (and sometimes their entire presence!) in the presence of louder neighbouring instruments.

Albeit, it is not just the audio rig that is important here. What if it is doing its job of resolving music at -50dB level, but the noise floor of your room is as high as 55-60dB? The passage will sound as if nothing is recorded here! So get a quiet air conditioning system and switch off that helicopter-like wheezing celling fan during a critical listening session.

What if you have a very clean source, but a low powered amplifier with a low sensitivity (low efficiency) loudspeaker? The source is resolving the full Dynamic Range, the amp is clean and is taking care of the low level linearity and microdynamics, but is not able to deliver the higher SPL finally. It goes into severe distortion as the music gets going and you have lost the upper part of the range. Anaemic budget systems and small speakers are often plagued with this disease.

Conversely, what if the system is resolving the louder part very well, with full force, but is just not coming to life on lower levels recordings (the recording is low at certain parts but not the volume level of the system)? Most of the discotheque and pub systems are living testimonies of this type of system. They are engineered to be played loud and thus have no life in them without a compensation into playback when they play quieter.

What if the dynamic range is good in most parts of the frequency (quality) span but not in its entirety? Typically, a respectable mid-budget system of a decent sized loudspeakers will be good enough throughout the frequency spectrum for all loudness levels, but will be hit be compression and will sweat on higher volume levels on the bass or lower-mid bass parts. Having larger woofers or smaller but multiple faster woofers will do the job better.

What if all of this is present in the system, but you are short of hearing?!! This is a serious issue that many individuals do not consider while evaluating a system. We live in industrial era and in noisy cities, most of us start losing significant part of hearing spectrum right though lour thirties. Since this doesn’t bring deafness, we do not acknowledge it – but qualitatively we have reduced response to the higher frequencies. I often see many individuals enjoying overly bright sound as perfectly okay, acceptable and pretty flat, this happens as the equaliser settings suddenly have compensated to their loss of hearing in the upper frequency region. For such an individual, the distorted spectrum curve when amplified louder than the usual reference level (due to loss of hearing) will often send even a good audio system into distortion and compression.

Thus Dynamic Range is a very important qualitative specification and not a mere number for it to be a quantitative phenomenon. Most of the listeners enjoy great Dynamic Range performance, but are not able to spell it out in actual term. They say they liked the clarity or ease of the system and the sound just was very soothing and that they were able to hear so many new thing that they missed out earlier.

Actually what they liked was clean sound in not just the frequency spectrum but throughout the loudness spectrum, uncompressed clean sound where even the tiniest of the nuances were holding on to the position as if they were double landlocked! They were probably startled several times when a hard spat on the drum diaphragm made them jump out of their skin when it was suddenly followed by a soft piece of lute or piano. They almost fell off their chair when the orchestra reached its crescendo – of course they survived it without lowering the volume level, as the sound was clean even at high SPLs!

Dynamic Range of a system is an important aspect and is proving to be evermore important due to increased range of higher resolution music and movie formats. Unlike the earlier times, we are now close to listening to uncompressed sound as if the band is in front of us – at least at the format level. Rest of the audio chain needs to follow.