The brass plaque honouring Alan Blumlein, to be affixed to the front of the Abbey Road Studios building

Alan Blumlein pioneer of stereo sound honoured at Abbey Road

Alan Blumlein, the engineer credited with inventing the recording and playback of stereo sound, was honoured today for his pioneering work at a special ceremony held at EMI's Abbey Road Studios in London.

The IEEE commemorative Milestone Plaque – only the fifth in London – was unveiled by Howard Michel, president and CEO of the IEEE, Isabel Garvey, managing director of Abbey Road Studios and Alan Blumlein's son Simon and grandson Alan. The plaque has been awarded “in recognition of Blumlein's enduring influence in recording technology”.

A blue plaque honouring Sir Edward Elgar, the first conductor/composer to record at the EMI studios, is already in place on the front of the building, to the left of the entrance. Blumlein's plaque is to be installed to the right.

Speaking at the event, grandson Alan Blumlein said, “Abbey Road Studios is the perfect location for this event and celebration. It is incredible to think that Alan Dower Blumlein made live stereo recordings in this legendary facility in 1934.”

Professor Tony Davies, former IEEE regional director, commented, “Remembering the achievements and inventions of the past is needed for proper understanding of the present and for helping engineers to solve current problems and invent the future. IEEE is therefore very pleased to be able to make this permanent recognition of these substantial stereo sound recording achievements of the 1930s which are still important today.”

One of Alan Blumlein's ribbon microphones It was while working for EMI – the company resulting from the merger of the Gramophone Company and Columbia, Blumlein's original employer – that Blumlein came up with a solution to the problem of recording music and speech stereophonically.

In December 1931, the 28-year-old Blumlein filed his most famous patent, #394.325, for “improvements in and relating to sound-transmission, sound-recording and sound-reproducing systems”. The patent contained 70 unique claims, including the positioning of a pair of microphones; processing of sound from the microphones; and cutting equipment to record two channels in to a single record groove. Together, these new ideas represented the beginning of stereo recording and stereo sound, which in time revolutionised the music and film industries.

Prior to his discovery, audio was captured in mono, which gave unsatisfactory and disorienting results, particularly for the cinema and the emerging television industry. Rather than an actor's voice following him or her as they moved across the sound stage, the vocal track stayed anchored to the single speaker typically reproducing the audio. In fact, it was while at the cinema with his wife one evening in 1931, that Blumlein confided in her that he had identified the issues holding back stereophonic capture and reproduction and already had ideas as to how to solve them. Blumlein reasoned that if a blind person were watching the film, they would have no idea where the speaker was on screen if the audio did not follow their movements.

The 1931 patent outlined Blumlein's solutions over 24 technically detailed pages, introducing what he described as his 'shuffling' circuit to preserve directional sound, which captured and replayed sound in stereo using a pair of omnidirectional or figure-8 pattern microphones. These microphones were arranged in a configuration known as a coincident pair, whereby the two are placed as close to occupying the same point in space as possible – generally with one capsule mounted directly over the other – and with each one pointing 90 degrees in the opposite direction. In this way, the two microphones capture the full stereo picture of whatever audio they are pointing towards. This microphone arrangement is still widely used in recording studios today – including at Abbey Road – and has become known as a 'Blumlein pair'.

An early Alan Blumlein stereo ribbon mic  As there were no high-quality figure-8 microphones available at that time, Blumlein designed and built his own, bringing them to Abbey Road Studios (or the St. John's Wood studio, as it was known at the time) in 1934 to record the London Philharmonic Orchestra. The recordings Blumlein made were audibly at least a match for, and largely superior to, similar recordings made before, and the case for stereophonic sound was successfully made.

Blumlein further demonstrated his discovery with a series of short films as demonstrations of the improvements brought by stereo sound, including the 'Walking Talking' film, in which Blumlein and colleagues repeatedly walk from left to right in front of the camera, counting from one to six as they pass. This film not only illustrated stereo sound, it also effectively demonstrated overlapping audio. Blumlein had already made the world's first stereo film, 'Trains at Hayes Station', as a demonstration piece. Blumlein was based at EMI's research and development labs at Hayes.

Although educationally a slow starter – it is said that he was unable to read or write until age 12 –
Blumlein nevertheless showed a keen interest in engineering from an early age. He was also particularly adept at building Meccano models, with a particular fondness for cranes, planes and trains. Aged 18, Blumlein got in to the City and Guilds college on a scholarship and within two years had graduated with a first-class honours degree in electrical engineering.

During his working lifetime Blumlein produced many notable achievements in his field, before his life was tragically cut short in 1942. On 7 June, aged only 38, while Blumlein was working on the development of the H25 radar system as part of the war effort, the Halifax bomber he was travelling in on a routine test exercise caught fire and crash-landed in the Wye valley, killing all those on board.

Ironically, it later transpired that at almost the precise moment of the accident, Winston Churchill had written a letter asking for 200 working units of the completed radar system, having recently been informed of the groundbreaking technical work already being undertaken. Despite the loss of key personnel in the crash, the development of the H25 radar had been in the final stages and the system was soon completed and installed by the RAF.

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