The experience of being at a concert is something else; it totally beats listening to your favourite song on your iPod. But, this statement doesn’t just have to do with the atmosphere and the rush of rocking it out with your idols; it has to do with a more subtle aspect. The difference is the ‘missing information’ in recorded music. Though for a regular listener, the song, when played on a music player, may sound complete in terms of duration, for a keen listener it is not the case in terms of impact.
Amar G. Bose, the maverick researcher who recently passed away, was one such keen listener — an audiophile who wanted to recreate the magic of live concerts at home. He chose research and teaching at Massachusetts Institute of Technology to accomplish his goal. Bose started the Bose Corporation in 1964 with the agenda of ‘Better sound through research”. Nearly 50 years after its inception, the corporation does deliver better sound through research.
Bose discovered a technique to recreate the wide space reflection that is inevitable in concerts, the reason live music sounds as brilliant as it does. In a concert, very little sound reaches the listener directly — a large portion of the sound is reflected and hence gives a rich quality when it superimposes with the direct rays of sound.
When we listen to music even with the 7.1 channel surround speakers at home, this feature is missing. Bose incorporated this technique in the corporation’s flagship stereo product Bose 901.
First released in 1968, Bose 901 is still running strong in its sixth edition. These stereo speakers use proprietary signal processing from Bose Corporation to render the concert-like effect, using only two speakers and an equaliser. The direct/reflecting technology in the Bose speakers as it is claimed in the product specification “brings the warmth, power and excitement of a concert hall to your home”.
Another important contribution that Bose made to acoustics has been noise cancellation headphones. It started with applications in avionics for pilots. Today, consumers seek noise cancellation earphones and headphones for an unfettered sound experience while on the move.
Loss of information
All recorded music, either while recording or digitisation, end up losing information. The loss of information happens when some of the tones are excluded when recording. Tones are the various frequencies an audio signal consists of.
The note C has its bass tone at 130.813 Hz, the middle C is at 261.626 Hz, vocal C at 523.251 Hz and soprano C at 1046.502 Hz, and it can have overtones appearing at higher multiple frequencies, which carry some portion of the energy.
In the process of recording, some of the higher tones are filtered out, for reasons such as data compression. The commonly used MP3 is a format that employs this lossy compression.
In the last couple of decades, with the reducing cost of digital storage, formats such as the Free Lossless Audio Codec (FLAC) are gaining popularity. These lossless formats consist of almost all the component frequencies and when played with the right audio systems can reproduce the live effect with high fidelity. A lossless version of B)eethoven’s Fifth Symphony can be about 150 MB, whereas the MP3 version could be around 20 MB. When a listener is keen on getting the best out of the entire spectrum, uses FLAC on a good audio system, he/she is qualified to be an audiophile
The human perception
Unlike other audiophile audio systems, Bose manufactures equipment that give importance to human perception, and not simply the circuit parameters.
In his landmark paper, Bose elucidated that the metric to measure the performance of audio system need not be circuit parameters such as attenuation or gain in power levels at different frequencies, or the number of channels. He believed, and Bose Corporation still believes, that sound perception by the human mind is the best metric. Bose’s research-oriented approach of making perception of sound the metric tried to broadly cater to users by analysing ‘psychoacoustics’.
Much like Freud’s work on psychoanalysis drew flak, Bose’s approach of incorporating psychoacoustic non-parameters has been criticised by audiophiles for decades.
With all the accolades and criticism, one fact remains: Bose brought state-of-the-art research into audio systems, leaving behind a legacy of equipment that fills the whole spectrum.