We have lots of cases in pro audio where specific techniques or sounds have names attached to them. This is understandable and useful, it’s a shorthand. Often these are referencing specific gear, places or musical styles: The Pultec trick, acid bass, New York compression.

But some things are named after people. In this article we look at 5 of these, who the people were and what their name got attached to.

Hafler Effect

If you’ve ever experimented with mid/side you’ll probably have auditioned the sides channel of a stereo mix. With the centre-panned vocals, bass, kick and snare cancelled you’ll have experienced how interesting this derivative of stereo can be. This isn’t news and David Hafler promoted the use of this difference channel as a way to create a pseudo surround sound experience using the Hafler Circiuit

By connecting one, or a pair of additional speakers behind the listener and connecting to both of the positive terminals of the amplifier, the effect can be very interesting. Apparently connection of a single additional speaker is recommended in the liner notes of Brian Eno’s Ambient 4, though if you’ve ever listened to the difference channel from an mp3 or lossy streaming you’ll know that the compression artefacts are very noticeable when auditioned in this way. You need lossless, or maybe go old-school with a half speed master on vinyl!

Blumlein Array

There are quite a few microphone techniques named after people. I’ll skip the Glyn Johns drum miking technique in favour of the Blumlein array as that means I can refer to Alan Blumlein, one of my audio heroes.

British engineer Alan Blumlein was one of the early developers of stereo sound. He was working on level-based stereo using coincident directional microphones at the same time as American research using spaced microphones was happening. This early work was carried out in the 1930s. His research also covered amplifier design and the development of television, but the war led him into research into radar and he was killed during a test flight in 1942.

The mic array which carries his name is a pair of coincident figure of 8 mics crossed at 90 degrees. It’s a great sounding array, though it should be used at the correct distance to avoid the phase cancellation of sound arriving at the rear of the array from very wide sources.

Fourier Transform

We’ve all benefitted from this. Everything from spectrum analysers, to tuning software, unmixing software and noise reduction rely on the ability to be able to extract information about complex sounds and the most powerful tool for this is Fourier analysis. Most people involved in audio have heard of this but rather fewer know how it actually works. It seems intuitive that we can’t unmix sounds which have been combined. In the same way as mixing different colours of paint, the constituent parts are normally unrecoverable. But they can be and that’s because of the Fourier Transform. The fast variety of this, the ‘FFT’, is behind much of the ‘impossible’ studio trickery we take for granted in our DAWs. 

Joseph Fourier was an eighteenth century French mathematician and in his 1822 book The Analytic Theory of Heat he laid the foundations for what would become the Fourier transform which can achieve the impossible and deconstruct a complex sound into its constituent sine waves. If you want to know more about how this works check out our article Amazing - How Sound Really Works

Haas Effect

The Haas effect is named after Dr. Helmut Haas, who in a 1951 paper examined the effect of a single acoustic reflection on the perception of speech. It’s sometime known as the precedence effect and it is one of the most powerful directional cues we use to locate sounds in space. As such its very important in stereo recording and mixing.

If two identical sounds arrive at each ear with a sufficiently short time between them, rather than being perceived as two sounds they are heard as a single sound and the direction from which they are perceived to have arrived is determined by which sound arrived first. This mimics the time of arrival differences introduced by the physical distance between the ears and this is why if the difference is too long the effect collapses and the sounds are heard as echoes of each other.

Spaced microphone arrays exploit timing differences to create stereo cues but these delays can be introduced artificially using a suitably short delay on one channel. These ‘Haas delays’ can be used as an alternative to level based panning.

Lombard Effect

This is the name given to an involuntary response in speakers when speaking in loud, noisy environments. As well as speaking louder, speakers also alter their pitch and rhythm. This sounds like stating the obvious. In a noisy environment people change the way the speak to make themselves heard over the background noise. The interesting thing about this effect isn’t the way speech changes but the fact that it is an involuntary response. I read that the presence of this response is used to detect ‘malingering’ in those feigning hearing loss. Exactly when and why this might be necessary isn’t something I’ve thought about before but the fact that such a practice exists illustrates how reliably this involuntary response occurs.

This is interesting to audio professionals because it’s so characteristic. I know from tutorial videos I’ve done that there is no disguising this involuntary effect when I’m talking over music. And if my headphones were loud but the track is mixed quiet relative to my Voiceover then the results are incongruous. This effect has been observed in non-human species and is known to affect singers, particularly in choirs, and people playing instruments.

Bonus - Brandolini’s Law

As a humorous addition to round off this collection I’ll nominate Brandolini’s Law as the most important eponymous discovery for an audio professional in the 2020s. This law states that the amount of energy needed to refute bullshit is an order of magnitude bigger than that required to produce it. This was named after Italian programmer Alberto Brandolini and is evidenced every day online in pro audio forums and the comments section of YouTube!

I have other discoveries on my ‘long list’ which might appear in a subsequent article. There are some big names which are absent. What eponymous audio discoveries would you have included? Share your thoughts in the comments.