Because of the way our hearing works, critical and objective comparing of two nearly identical performances is difficult. Some people go as far as to claim that certain changes in the audio system (such as swapping cables, for example) have no audible effect at all. In my opinion, with thorough understanding of the way human hearing works, a procedure can be established, that will allow anyone who has healthy ears to perceive even very minute differences with minimal difficulty.
Listening is a very special way of perceiving the world. Unlike vision, hearing is strictly connected with time - you cannot stop and carefully examine a sound with a magnifying glass. Our first goal then, if we are to critically and objectively assess the sound, is to maximise our auditory perception abilities.
Of course, the circumstances will never be truly perfect, so you can take the preparations as far as you like. So long as you are well, and you conduct your auditions at more or less the same time of the day, you should get reliable (and repeatable) results.
Once you have prepared your listening environment, you can commence the actual testing. The procedure described below is applicable to testing single components, as well as entire devices.
The crucial condition for reliable evaluation is that you must be able to swap between your reference and test components quickly - under 30 seconds, ideally. This is because sonic memory is very volatile, and quickly degrades - it becomes infused with moods, other memories, in other words, becomes unreliable. One can memorise melodies and rhythms easily enough for a long time, but it is very difficult to memorise exact sounds: their precise timbre, attack, decay etc. You can probably remember certain sounds very well - the way you bedroom door creaks, your car engine starts and so on - they are the sounds you are exposed to every day. Remembering one-off sounds is much more difficult, hence the necessity to cut the wait time to minimum.
This condition is easily met for entire devices (you just swap cables or switch inputs at the amplifier). For single components such as resistors or capacitors, it usually requires a dedicated system in place, that will allow such quick swapping.
My preferred method is to install a "3-pin fan connector" socket in place of a component (see picture on the right). These sockets are cheap or free if you cut them off a broken PC fan. They accept virtually all commonly used wire diameters - although you may have to drill out the socket holes slightly to accommodate some big electrolytic caps. These sockets have the same hole spacing as many standard components (all TO-220 devices for example), and can be either soldered directly onto PCB, or with an extension cable for ease of access. Once a socket is installed, all I need to do is power-off my test setup, take out one test component, plug in the other one and power back on, which typically takes under 30 seconds.
Another crucial condition for the test is that you listen in exactly the same conditions, so as to eliminate all other variables. Use the same seating position, same lighting conditions, etc.
Once you are satisfied that you will be able to conduct the swaps quickly and effortlessly, it is time for the actual audition:
Following this procedure will allow you to discern relatively small characteristics reliably to the point that blind or non-blind testing making will make negligible difference. It is not easy - it can be actually quite an exhausting activity, as it requires perfect focus throughout the entire audition. But with practise and over time, you will tire less. More importantly, you will increase trust in your ears because you will notice your observations are accurate and consistent.
Copyright © 2009-13 Jaroslaw Biniek.