On Tuesday, Jan. 13, Edwin Pfanzagl-Cardone presented his latest book, “The Art and Science of 3D Audio,” at an ÖTMV (Austrian Association of Sound and Music Designers) event held in cooperation with AES Austria (Audio Engineering Society) and the Austrian Academy of Sciences (ÖAW). This publication marks his second major work, following “The Art and Science of Surround and Stereo Recording — Including 3D Audio Techniques,” originally published as part of his doctoral thesis.
Pfanzagl-Cardone previously taught “Theory of Audio Engineering” at the Institute of Electroacoustics at the University of Music and Performing Arts Vienna (mdw) from 1994 to 1999 and has served as Head of Sound at Austria’s prestigious Salzburg Festival since 2000.
Alongside his academic and artistic work, he has conducted extensive research in the field of 5.1 surround microphone techniques, leading to the development of the “AB-Polycardioid Centerfill” and “ORTF-Triple” systems, as well as the “BPT” (Blumlein–Pfanzagl–Triple) microphone technique.
In an interview with the NYC Daily Post, Edwin Pfanzagl-Cardone reflected on the conceptual foundations of his work, his long-standing pursuit of perceptually accurate spatial reproduction and the practical implications of 3D audio for contemporary music recording and production.
Q. After several years of piano lessons, you studied communications engineering and electronics at the TGM, graduating with distinction. Which early influences or experiences motivated you to choose this path — and subsequently to pursue audio engineering studies at the mdw?
A. My interest in music, later in my own compositions (from around the age of 14), and thus also in the need for the associated music recording, occupied me from my mid-teenage years onward. However, my parents were of the opinion that I should learn something “solid” before turning to sound engineering. Therefore, I decided — an interest in electronics was already present, thanks to an electronics hobby construction kit that I received at around the age of 11 — to first complete the college program in electrical communications engineering and electronics … and was then fortunate enough to pass the entrance examination for the audio engineering program. From around the age of 16/17, I was also active as a keyboard player in our school band.
Q. From 1994 to 1999, you worked as a lecturer in the main subject “Theory of Audio Engineering” at the mdw before becoming Head of Sound of the Salzburg Festival. How did you experience the balance between theoretical teaching and practical work, and which experiences were particularly formative for you?
A. At that time, I worked throughout the year as an audio engineer primarily in pop music and speech recording for radio, television, and film. Recording classical music was therefore mainly possible only during the summer months, and partly during the Easter Festival, at that time still as a freelance audio engineer.
Q. You are the inventor of the “ORTF Triple” and the BPT “Blumlein–Pfanzagl Triple” surround microphone techniques. Which ideas or problems were you aiming to solve with these developments — and were there any surprising insights from practical application?
A. ORTF Triple:
Sometimes it is ‘coincidences’ in life that determine the path one follows. The fact that the only stereo microphone in the Salzburg Festival inventory was a Schoeps ORTF microphone naturally brought it into focus for my first orchestral recordings in the Large Festival Hall. Through another coincidence, I became aware of the relevance of phase accuracy when mixing main and spot microphones. This initiated a thought process around 2001–2002 regarding how the correlation of two-channel main microphone signals across frequency might be constituted, and what sonic effects this has. The development of the ORTF Triple, with an additional cardioid capsule in the center, was a pragmatic solution to provide a center signal for the front loudspeaker while maintaining stable orchestral imaging.
BPT (Blumlein–Pfanzagl Triple):
The idea for this approach emerged around 2003 during a chamber music tour to Japan, where I accompanied my wife, a pianist. Originally, I developed the BPT arrangement in the search for a coincident (“koinzident”) microphone configuration capable of recording any solo instrument — in this case, the piano — in true stereophonic form, while also providing a discrete center signal for 5.1 surround recordings with L, C, and R front channels. A central objective was to achieve this with the lowest possible degree of localization distortion.
Subsequently, it became apparent that the BPT – at that time still constructed discretely from three Neumann U 87 microphones — was also highly effective in reproducing small ensemble formations with accurate spatial imaging. The logical next step was therefore to evaluate its performance with larger sound sources, such as orchestras, where the results proved to be excellent — a judgement I may cautiously allow myself as the inventor of the technique, but one that is also consistently and unsolicitedly confirmed by colleagues.
With a certain degree of satisfaction, I can note that the very naturally sounding AB-BPT technique, a combination of wide-AB omnis with the coincident BPT-microphone as a “centerfill” (to avoide the typical “hole in the middle” sonic perception which often comes along with large-AB techniques), which we use on almost all concert documentary recordings in our three main halls, has also been well received by members of the Vienna Philharmonic Orchestra. This is reflected in their decision to select several of our archival recordings for release as part of their “Special Annual Edition” CD series, beginning with the 2019 live recording of Berio/Bartók conducted by Esa-Pekka Salonen.
In this context, the use of the acoustic absorber panel — which is also discussed in my book — is of critical importance, particularly when the BPT is positioned at a greater distance from the sound source. Under such conditions, sound components arriving from behind — originating in the hall — must be attenuated in order to maintain a balanced and appropriate direct-to-diffuse sound ratio.
Q. At the KUG, you also completed your doctoral studies on the topic “Signal Correlation and Spatial Impression in Stereo and 5.1 Surround Recordings.” Which key findings from your research were particularly influential for your work as audio engineer?
A. Key insights were that the optimal “natural” sonic impression is achieved primarily by approximating the “original sound in the concert hall” as closely as possible at a “best seat of the house” position, assuming a good-sounding concert hall. I perceive the mixes of some colleagues who use many spot microphones as unnatural, because I can hear the close microphone — instrument distance due to the unnatural or unfamiliar sound. For me, the benchmark remains how an instrument sounds in the audience area, and not how it sounds at a distance of 50 cm from the performer.
The fact that this concert-hall sound reproduction — achieved through optimized microphone techniques such as AB-BPT — also shows the closest correlation, from a measurement perspective, with the binaural signal of an artificial head, positioned at a “best seat in the house,” proved decisive for me. This includes the highest preference ratings from listeners in double-blind listening tests. Taken together, these findings constituted the conclusive evidence for the validity of my recording approach, which I refer to as “Natural Perspective.” The opening section of my book presentation addressed this relationship explicitly, with reference to the BQI (“Binaural Quality Index”)” and BQIrep, the newly defined “Binaural Quality Index of reproduced music.””
Q. Your dissertation and your research in the fields of computer-assisted composition and 5.1 surround microphone techniques led to your first book, “The Art and Science of Surround and Stereo Recording — Including 3D Audio Techniques.” Which gap or central question were you aiming to address with this book?
A. The starting point of my continued engagement in sound engineering after completing my studies was a question posed by one of my students: if “small-spaced AB” — according to findings in psychoacoustics — delivers the correct image in terms of localization, then “wide AB” cannot also be correct, can it? This was a highly justified question, especially given that RCA ‘Living Stereo’ recordings from the 1950s and 1960s, which used wide AB, are still regarded as reference recordings.
Based on his measurements, Pfanzagl-Cardone demonstrated that “small-spaced AB,” due to high low-frequency signal correlation, is incapable of delivering good spatial imaging, whereas “wide AB”, as well as Blumlein pairs and BPT, perform well.
Q. On Jan. 13, as part of an ÖTMV event in cooperation with AES Austria and the ÖAW, you presented your latest book, “The Art and Science of 3D Audio Recording.” What do you consider the most exciting developments in the field of 3D audio that you address in this book?
A. The flexibility offered by various software solutions for 3D audio mixing, regarding source positioning and “downmix” generation, from formats with a higher number of channels, is highly exciting. Ultimately, though, the key question is whether the end result sounds natural and spatially convincing, even after 3D encoding.
Q. Which acoustic or technical challenges must be solved in order to create a convincing 3D sound experience? Are there typical mistakes made when recording 3D audio, and how can they be avoided?
A. Correct selection of the 3D microphone technique — depending on the size and nature of the sound source and the room — and room-appropriate placement of the microphones — taking the critical distance into account — is essential. In some cases, the loudspeaker reproduction format must already be considered as well. During mixing, achieving appropriate signal de-correlation between channels is crucial to creating a convincing spatial impression.
The decision making process towards this goal already starts with the choice of microphone directivity and many sound-engineers find themselves using super- or hyper-cardioids (instead of cardioids) as spot-mics for the sake of more precise sound-source localisation and better channel separation in 3D audio.
Q. Psychoacoustics plays a major role in 3D recordings. Were there any surprising insights into how humans perceive sound spatially?
With stereo — and to a lesser extent surround — recordings, suboptimal microphone techniques could often be masked in mixing. In 3D audio, however, the spatial naturalness must be convincing, or it will be perceived as unnatural. Surprising findings include frequency-dependent vertical localization distortions for sound sources reproduced via a center speaker. Details can be found in the ‘Spatial Hearing’ chapters of my two books.
Q. Which developments in 3D audio technology do you foresee in the coming years — will it become a standard for concert recordings or remain a niche field?
A. Good question. I believe 3D audio will remain a niche for the time being — primarily in cinema or high-end ‘home cinema’ setups for music — because the loudspeaker arrangements required for classical music at home are simply too complex. In the pop music domain, however, we are already seeing how successfully binaurally encoded 3D audio has been adopted on streaming platforms.
Q. For young audio engineers or musicians who are interested in 3D audio: which first steps would you recommend to approach this complex field?
A, “For classical or acoustic music, attend as many concerts as possible — and listen with your eyes closed! Immerse yourself in the hall’s sonic environment and internalize the spatial impressions. Ideally, experience performances from different seats to appreciate how perspective and acoustics change.
For pop music, study a wide range of reference recordings within your stylistic preferences. Analyze how the engineers positioned and treated the sound sources, and pay attention to how spatial effects were created and balanced.”
Bridging science and practice
Pfanzagl-Cardone’s work uniquely bridges scientific research, technical innovation and artistic practice, providing both a conceptual framework and practical tools for achieving highly realistic 3D audio recordings. Through his inventive microphone techniques, careful analysis of spatial acoustics and commitment to perceptual accuracy, he has made a lasting impact on the field of audio engineering. His books not only document decades of experience but also provide guidance for the next generation of sound engineers seeking to capture music from the “Natural Perspective.” For those interested in a more hands-on exploration of his methods, his “Mic-Tech Analysis” video series on the YouTube channel FUTURESONIC100 offers detailed demonstrations and analyses of his microphone techniques.
His book “The Art and Science of 3D Audio Recording” is available for purchase here for anyone looking to dive deeper into his approach.
Photos by Martin Lukesch and Hannah Lena Rebel
Edited by James Sutton
