Hi-Fi Audio Systems, Binaural Recording

By Xah Lee. Date:

Some random thoughts on hi-fi audio systems.

High-end audio cables. Expensive monster cables improving music quality is pretty much a urban legend.

Studio monitor means loudspeakers used by pro that tries to reproduce input signal faithfully. Though, of course, the term has also been abused by marketing.

Loudness war. A phenomenon of louder and louder music recordings produced thru the years. A sorta arms race between music producing companies. LOL. Quite stupid. Of course, physically this cannot be done without distortion.

Hi-fi. Basically a useless marketing term. The quality of what's considered hi-fi equipment basically improves thru the years. So, today's hi-fi is tomorrow's lo-fi.

Interesting quote from the hi-fi article:

When high fidelity was limited to monophonic sound reproduction, a realistic approximation to what the listener would experience in a concert hall was limited. The general clarity of the sound, however, was not any less than with stereophonic sound reproduction. Researchers quickly realized that the ideal way to experience music played back on audio equipment was through multiple transmission channels, but the technology was not available at that time. It was, for example, discovered that a realistic representation of the separation between performers in an orchestra from an ideal listening position in the concert hall would require at least three loudspeakers for the front channels. For the reproduction of the reverberation, at least two loudspeakers placed behind or to the sides of the listener were required.

The above leads to stereo and surround sound systems.

Stereo and Surround Sound

Surround sound. Not much interesting thing here. Surround sound is basically how many speakers. At the lowest, we have mono recording, played by using just one speaker being sufficient (more speakers doesn't add sound quality). Then, we have stereo. That's sound recorded and reproduced in 2 channels, played back thru 2 speakers. The goal is to emulate realism. Basically, the more channel/speakers, the more realism you can reproduce. Surround sound today is typically 5 speakers. Taking to extreme, you may have 30 or more channels/speakers that literally surround the listener around a sphere.

How many channels is sufficiently enough to replicate realism is ultimated limited to the number of ears on a human animal. That is, 2. So, theoretically, 2 channel/speakers, is enough! This in fact can be done with earphones. The recording and reproducing sound into just 2 channels emulating the human ears, is called Binaural recording. Listen to the recording provided there. That's fantastic.

Binaural Recording

In my opinion, binaural is the most elegant, most superior, form of audio reproduction and listening method. In a public theater or home theater situation, if each person doesn't mind putting on a headphone/earphone, then the audio quality will beat and possibly advance surround sound system of the future. Because, surround sound ultimately has to reproduce sound in the open, while binaural system try to reproduce sound directly for the human animal's input system: the ears.

The problem of adopting binaural for general audio recordings is that, the resulting record must be played back thru headphones. If they are played back thru speakers that are not just beside the ears, then it sound very bad. This is understandable, since binaural signal is by design to be played back directly around human ears, in contrast, stereo or surround sound are designed to reproduce the signal of few more sound sources remote from the ears.

In any case, binaural is great. I think recordings should have this format. Possibly, sometimes in the future all recordings will have binaural format.

Normal Headphones/Earphones Are Not Flat Response

One important thing i learned from the binaural article is that, normal headphones/earphones, are not “flat” by necessity. Because, sound source far from the ear is very different when the same sound source is played back near the near in a reduced volume. This means, normal earphone hardware actually must adjust this. This also means, when a binaural recording is played thru normal earphones, it does not sound as great as if you have a flat response earphone. Here's a quote:

The fact that most headphones are actually designed to have a notch in the 5 kHz region is not widely understood, and this may have led to errors in the assessment of binaural recordings, since flat headphones are not normally available, and 'high quality' headphones incorporate the notch just like any others, though perhaps with a better approximation to that needed by the average ear. Male and female ears are of course different in size, and the outer ear gets bigger with increasing age, raising the possibility that most headphones are only really suited to young men. If headphones were designed to be flat, with a choice of equalisations available in headphone amplifiers, then headphone listening could be a more controlled experience, whether in binaural or stereo mode.