Audio Engineering Society UK

Title: ‘Critical listening/evaluation – a path to the future of quality music’
Location: Royal Academy of Engineering, London
Description: George Massenburg of George Massenburg Labs
Start Time: 18:30 for 19:00
Date: 3rd June 2009

George Massenburg needs little introduction – even if you don’t know of him, you have probably heard his recordings. For a detailed biography, see www.massenburg.com/cgi-bin/ml/bio.html.

Meeting Report

Quality recordings

What is difficult to represent in this report is the passion George exudes about music, a passion which drives him to strive (and help others to strive) to continually improve the quality of recorded music. Many recordings were replayed in the course of this lecture, some made by George, others not. Most were 192kHz, 24-bit; some were transferred from analogue master tapes.

George began by replaying a Diana Krall track, pointing out the subtlety and detail captured by Al Schmitt. In a change of style, the next track was by Neil Young – a new song about the recent financial crisis with the chorus line “A bailout is coming, but not for you”. Elements of the recording were described, there being a pair of guitars (slide and acoustic), rock’n'roll drums and a hi-hat “somewhere in the background”.

George then played a clip from YouTube of a recent and currently very popular track by Autotune The News (their second track, pirates. drugs. gay marriage), an original piece where television newsreaders have been cleverly edited in time and pitch such that they appear to be singing. The point here? Although the YouTube clip has been extremely popular (it received 1.5 million hits in the first week, possibly setting a web record), and although George admitted to thinking it “brilliant”, the audio quality is very poor. George pointed out that repeated listening at this YouTube-quality quickly gets very annoying because of the low-fidelity sound.

Compression Artefacts

George then played the results of some subtraction tests on lossy audio codecs, a technique which George refers to as the Moorer test as it was originally suggested by James A Moorer. In these tests, high-quality 192kHz, 24-bit recordings were converted to various encoded forms such as MP3 and AAC. The encoded files were then decoded and upsampled back to the original 192kHz, 24-bit. A sample-by-sample subtraction was then performed, and the resultant difference – the error introduced by the codec – then replayed. The resulting error signal is surprisingly high in amplitude (estimated by George as typically 25-30% peak), clearly correlated to the signal and with a complex relationship to the original sound (not simple harmonic distortion).

George takes the view that his students should learn to recognise the nature of the codec error using this subtraction method and then listen to the encoded music. Using this learning technique, listeners can familiarise themselves with the artefacts’ sound in isolation, and can subsequently pick them out more readily when the encoded material is played.

Listen Again

George believes that every time we hear a piece of music we should have the possibility of hearing something new – “to take home something else” – and that this is more readily achieved with high resolution recordings. Although George concedes that it’s possible to make a “pretty good” 44.1kHz/16-bit CDs, he remembers the first time he heard a digital recording: rather than being impressed, he was “horrified”.

Subsequent work to push the boundaries of converter technology (George recalls the contribution of Paul Frindle in this area) has convinced him that good digital now is good. He believes that we don’t have to go back to magnetic tape to make good records, and describes himself as having “an easy peace” with both vinyl and analogue tape.

Recording Tips

George deprecates recording techniques in which small elements are recorded separately and later combined/corrected/stretched/re-tuned, etc. He believes a key to great music recording is to maintain a performance focus. Preferably, the band should perform and be recorded playing simultaneously in the same space. George offers these suggestions to help your next recording:

• 1) Only use destructive record.
• 2) No punch-ins.
• 3) No one is allowed to take the recording home and ‘tweak’ it – they can do another take, but the previous one will be overwritten.

The AES UK section and George wish to thank the companies who kindly supplied equipment for this lecture, namely ATC (monitor loudspeakers), Digidesign (ProTools system), Arcam (DVD player) and Prism Sound (D/A converters).

Report by Nathan Bentall (edited by Keith Howard)