Brett Leonard

Loudspeakers and headphones: The effects of playback systems on listening test subjects

Many modern listening test designers disagree on the best playback system to be used when conducting tests. The preference often tends toward headphone-based monitoring in order to minimize the possibility of undesirable acoustical interactions with less than ideal testing environments. On the other hand, most recording and mixing engineers prefer to monitor on loudspeakers, citing a greater ability to make critical decisions on level balances and effects. While anecdotal evidence suggests that differences exist between systems, there is little quantified, perceptually based data to guide both listening test designers and engineers in what differences to expect when alternating between monitoring systems. Controlled tests are conducted with highly trained subjects manipulating the level of solo musical elements against a backing track, using both headphones and loudspeakers. This task serves to make the results equally applicable to critical mixing tasks and rigorous listening tests. The results from both...

Real rooms vs. artificial reverberation: An evaluation of actual source audio vs. artificial ambience in the rear height channels of immersive audio systems

Many spatial audio researchers and content producers agree that the best source material for height channels in immersive audio is provided by the capture of actual elevated channels in the room. Particularly for music recording, this technique is preferred as opposed to signal processing, providing a more natural and realistic impression of immersion. While previous work has proven this to be the case in the front channels of various 3D playback systems such as 22.2, the content of the rear height channels has not been specifically evaluated in this respect. Multichannel audio recording, specifically 3D recording, can be a cumbersome task as the channel counts expand—and so the question arises—is it really necessary to capture discrete rear height information? This research compares four height channel capture points are compared to two capture points applied to the front height channels in conjunction with artificial reverberation in the rear channels. A two-part study is employed—the first is a simple ...

Real Rooms vs. Artificial Reverberation: An evaluation of actual source audio vs. artificial ambience

Many spatial audio researchers and content producers agree that the best source material for height channels in immersive audio is provided by the capture of actual elevated channels in the room. Particularly for music recording, this technique is preferred as opposed to signal processing, providing a more natural and realisti impression of immersion. While previous work has proven this to be the case in the front channels of various 3D playback systems such as 22.2, the content of the rear height channels has not been specifically evaluated. Multichannel audio recording, specifically 3D recording can be a cumbersome task as the channel counts expand - and so the question arises - is it really necessary to capture discrete rear height information? This research compares four height channel capture points compared to two capture points applied to the front height channels in conjunction with artificial reverberation in the rear channels. A two-part study is employed - the first is a simple ABX test to determine discriminability between the real rooms and the artificially generated version. Part two is a preference test, based on several standard acoustic/perceptual descriptors, revealing the subtle differences between real and artificial rear height channel information.Many spatial audio researchers and content producers agree that the best source material for height channels in immersive audio is provided by the capture of actual elevated channels in the room. Particularly for music recording, this technique is preferred as opposed to signal processing, providing a more natural and realisti impression of immersion. While previous work has proven this to be the case in the front channels of various 3D playback systems such as 22.2, the content of the rear height channels has not been specifically evaluated. Multichannel audio recording, specifically 3D recording can be a cumbersome task as the channel counts expand - and so the question arises - is it really necessary to capture discrete rear height information? This research compares four height channel capture points compared to two capture points applied to the front height channels in conjunction with artificial reverberation in the rear channels. A two-part study is employed - the first is a simple ABX test to dete...

A study of variance of spectral content and sound radiation in timpani player

Timpani, although limited in pitch material, have the ability to produce many subtle colors, exceeding most other membranophones. One of the most notable characteristics of timpani is the perceptual “bloom” of the sound as distance is increased with the drum. Timpanists spend many hours working on control of these sounds and the bloom through application of intricate mallet technique and striking location. Anecdotal evidence of these differences is passed down through generations of teachers and students, but very little objective data exists about the actual sound of the drums, and the variations that occur between players. This study endeavors to reveal the objective differences between players and techniques, particularly as it relates to the “bloom” of the sound as you move away from the drum. Control of this directivity and expansion of perceived sound at a distance may be the single most important factor in the quality of a timpanist’s sound. Measurements are taken at different distances and locatio...

Interaction between critical listening environment acoustics and listener reverberation preference

Reverberation is a central effect in many modern music productions. In the case of classical music, it may even be the only effect used. There is, however, minimal literature concerning the interaction between reverberation preference and the listening environment used during critical mixing tasks. In order to explore this critical interaction, a group of highly trained subjects are tasked with adding reverberation to dry, premixed stereo program material in two different acoustic environments: a recording studio control room and a highly reflective room. The control room is representative of most studios, with an RT of approximately 200 ms. The reflective environment more closely approximates an untreated residential room, with an RT of over 350 ms, with a marked increase in lateral energy. Somewhat predictably, the mean preferred reverberation level is higher in a less reverberant environment, but the distributions of reverberation level preference are shown to be narrower for the more reflective mixing...

The practical effects of mixing in an environment closely resembling a home listening environment

Two traditional philosophies exist when considering recording studio control room design: the method of closely replicating the listening environment of the consumer, quite often the typical living room, as juxtaposed to the idea that the control room should be uniquely suited toward color-free critical listening. While both of these design philosophies have had their proponents and detractors, very little data have been gathered to show the merits or drawbacks of either when used for critical recording and mixing work. A novel method of task-based testing is developed to determine what, if any, affects can be attributed to particular aspects of control room designs. The method employs highly trained recording engineers and producers to provide real-world feedback on the makeup of a control rooms sidewalls. By having these trained subjects to perform basic mixing tasks while altering the reflectivity and diffusiveness of the sidewalls, the effects of these isolated acoustic features are determined. Data ...

The Instrument & the Room: A study of the grand piano focused on the needs of audio education

Through their training and education, aspiring recording engineers often encounter literature on the radiation patterns of typical musical instruments. The study of this information can greatly inform the placement of microphones and facilitate ones learning about the way acoustic instruments work. These musical acoustics studies, however, typically employ an anechoic or near-anechoic environment to minimize reflections from interfering with the instrument under test. Since the recording engineer works almost exclusively in environments with reflective surfaces, this causes a disconnect and can inhibit a full understanding of the relationship between the instrument and its environment. A case study of the acoustic grand piano is presented in which the instrument and the non-anechoic room are presented as a single, coupled acoustic system. Over 1300 measurement points are used to characterize the instrument/room combination. The study is conducted in both a small recording space and a large scoring stage,...