The audiophile world is replete with dubious products that claim to provide ultra-high fidelity sound with eye-popping price tags accompanying them. But what has research shown? Has anyone been able to apply scientific principles to find methods within this madness? When it comes to loudspeaker design, research conducted by institutions and manufacturers has found several characteristics that loudspeakers should possess. Before diving into the findings, we should discuss how researchers got there.
What makes a loudspeaker “good” is ultimately whether the human ear likes the sound. The question then becomes, can the subjective impressions of listeners be correlated to objective laboratory measurements? As it turns out, the answer is yes, albeit with some qualifications.
In the right setting, the human auditory system is a reliable instrument for judging the sound of a loudspeaker. Provided listeners are not suffering from some form of hearing loss, they tend to prefer the sound quality of the same loudspeaker when several loudspeakers are compared in listening tests. There are some variations from listener to listener, but not nearly as much as one might expect. So, what is “the right setting”?
Blind listening tests are important. Put two loudspeakers in front of a listener: Loudspeaker A is from a famous brand but the sound has some idiosyncrasies, and Loudspeaker B is from an unknown brand but does not have any peculiarities. Loudspeaker A will win consistently. Listeners have trouble separating what they see and know from what they hear. But hide the loudspeakers from view using a visually opaque but acoustically transparent screen, and Loudspeaker B will win consistently.
Based on well-controlled listening tests, researchers have found that listeners prefer the following:
- The ability to reproduce low frequencies (bass). This comes as no surprise – a loudspeaker that can reproduce low-frequency content such as bass notes and the rumble from movie explosions is preferred to one that can’t.
- Direct sound that has a relatively flat frequency response. Direct sound travels directly from the loudspeaker to the listener without reflections. The frequency response is a measure of how accurately the loudspeaker reproduces a signal over the audible frequency range. A perfectly flat frequency response means the loudspeaker is reproducing the signal without any changes.
- Wide Dispersion. Contrary to popular belief that loudspeakers should interact with the room as little as possible, research indicates that a loudspeaker with wide dispersion that enables strong reflections from the side walls is generally preferred, provided the reflections have a similar spectrum to the direct sound.
This just scratches the surface of the research, but it’s encouraging to know that evidence-based loudspeaker design is possible. While studio monitor designs are typically based on these findings, the extent to which home loudspeaker designs follow the research varies wildly. There isn’t much correlation between sound quality and price in the home audio world, and good sound doesn’t need to cost a fortune. Some manufacturers have started publishing white papers on their designs to demystify their products. So don’t get taken to the cleaners by the fast-talking snake oil salesman looking to make a quick buck.