September 2021

Beyond Stereo, Speakers, And Reproduced Sound
Should the ultimate goal of a loudspeaker be to faithfully reproduce sound as it was originated at the source.
Editorial By J. Martins

  There is still a lot to learn and improve with speakers, and how electroacoustic systems translate audio sources. Loudspeakers were originally designed to translate and amplify direct sound sources, starting with speech. Since the invention of sound recording, multitrack music recording, and the transition from mono to stereo, the simplistic goal of "sound amplification" and realistic reproduction has turned into a complex equation.

Should the ultimate goal of a loudspeaker be to faithfully reproduce sound as it was originated at the source? Or translate the recording itself? Or should it translate the result of a mix of sound sources (some of which have no acoustic origin and are purely synthesized) as it was produced in the studio? And what about the unique sound signatures of microphones or electronic circuits, which were intently used for its "coloration" effect in the sound? And what about acoustics and electroacoustics interactions?

All those questions were meticulously explored by our late and highly esteemed author Ron Tipton (1936–2018) in his fascinating and extensive article series titled "The Continuing Quest for Realistic Recorded Sound Reproduction." Ron expressed that exact complexity in the first sentence of the first of more than 40 articles on the topic, addressing how "conventional stereo" was recorded and the different microphone techniques. The more Ron explored the multiple efforts for "realistic sound reproduction" in his series, the more we understood how that quest was an enjoyable, but neverending journey.

In this edition, audioXpress pays tribute to Roger Russell (1935-2021), who also devoted his life to the pursuit of audio reproduction and speaker design. With a fascination for stereo recordings and realistic sound reproduction, Roger designed speakers that aimed to translate the live performance experience. He was also an enthusiast of high fidelity and how audio equipment could translate recordings in home environments. He understood the basics of human hearing science and acoustic interactions and was not afraid to empirically accept and play with them. In fact, he enjoyed how modern recordings (and music genres) could generate emotions from those interactions. "Stereo is still limited in part by recording methods, speakers, and room acoustics. Binaural recording and headphone playback eliminate the effects of the speaker and room but lacks the body perception of high level sound and lower frequencies as well as the freedom of turning the head to localize sounds," he wrote.

Today, we are able to enjoy those emotions he described with much more sophisticated immersive audio content using 7.1.4 Dolby Atmos speaker systems, and we are extremely close to realizing binaural spatial audio processing on headphones with head-tracking. The goal seems to go "beyond stereo," even if the intended goals for music are not yet clear.

In this Speaker Focus edition of audioXpress, we feature the work of Peter H. Lehmann, an author who has focused his efforts to enhance reproduction and "fix stereo." As he wrote, "In a stereo recording of music, instruments recorded to be heard as positioned directly in front of the listener are heard less distinctly than those instruments recorded predominantly to either the left or right channel of the recording." Not happy with the resulting phantom image that normally should result of correctly positioned left/right speakers in a listening environment — which strongly depends upon the original recording translating the "multi-directional perspective" that results from a truly "stereophonic" effect — Lehmann designed an "upmix" solution to derive a "real" center channel from the left and right channels of any conventional stereo recording.

Many companies are also currently researching the holy grail of "beyond stereo," now conveyed predominantly as "spatial audio" resulting from the reproduction of multichannel, object-based, or higher-order ambisonics (HOA) generated content.

It is my firm belief that we need to realize the spatial audio potential first and foremost using loudspeakers in order to convince consumers. And one could hope that more consensus about basic reproduction systems, such as stereo music, could have been achieved before departing on the "spatial" voyage.

J. Martins
Editor-in-Chief

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