Floyd E Toole

Retired, Consultant to Harman International

The steady-state amplitude response measured at listening locations in a room is a widely accepted indicator of sound quality in sound reproduction systems. Room equalization schemes adjust the room curve to match a target believing that this ensures good and consistent sound. This paper examines both small and large venues, home theaters to cinema...

The vast majority of music we enjoy is generated by loudspeakers of differing pedigree and propagated to our ears through spaces that can mostly be described as acoustically arbitrary. In spite of the obvious huge variations, humans have managed to not only enjoy reproduced music, but sometimes even to exhibit enthusiasm for it. Common acoustical m...

The physical measures by which acousticians evaluate the performance of rooms have evolved in large performance spaces—concert halls. They rely on assumptions that become progressively less valid as spaces get smaller and more acoustically absorptive. In listening rooms the loudspeakers and the rooms interact differently below and above a transitio...

The design criteria, features and acoustic measurements of a new listening laboratory designed specifically for listening tests on multichannel loudspeakers and components are described. Among its features is a novel automated speaker shuffler that eliminates loudspeaker position effects or allows the variable to be efficiently tested. Other featur...

A synopsis of scientific investigations into the physical acoustics of loudspeakers, how they interact with rooms, and the perceptions that result. From this comes a psychoacoustic understanding of what needs to be measured and how the measurements can be usefully interpreted. Practical advice is offered on how to maximize the performance of loudsp...

The physical measures by which acousticians evaluate the performance of rooms have evolved in large performance spaces-concert halls. They rely on assumptions that become progressively less valid as spaces get smaller and more acoustically absorptive. In listening rooms the loudspeakers and the rooms interact differently below and above a transitio...

In contrast to the considerable effort invested in concert halls and auditoria for live performances, the design of domestic listening spaces and recording control rooms has evolved with little guidance from science. In this presentation, an examination of the physical aspects of sound in small rooms reveals that traditional acoustical measures, su...

A review of the effects of reflections on perceptions of sound quality, direction, image size, spaciousness, speech intelligibility, etc., lending perspective to the matter of which elements might be perceptually important in multichannel sound reproduction systems. In general they appear to be less problematic than is commonly believed. This, comb...

Workstations are widely used as production environments for multimedia, film, and audio programs. For many consumers, they are also the delivery systems for these programs, as well as for others, like music, television, and films, intended for reproduction in various conventional systems and environments. Listeners in workstations therefore must be...

The design of loudspeakers is gradually being put on a scientific basis. Art and intuition have given way to engineering guidelines as the relationships between perceptions and technical measurements have been elucidated. Indeed, within limited circumstances, loudspeakers can be designed to meet specific engineering design objectives, with consider...

Reflected sounds influence the timbre and spatial character of live and reproduced sounds. Most investigations of reflections have focused on the performance of live sounds in large halls. Current interest in the acoustical interactions of rooms, loud-speakers, and listeners requires further and possibly more relevant data than have been available....

Resonances are fundamental to the production of musical pitch and timbre. A review of previous work and new experimental results describe the thresholds of audibility of resonances as a function of frequency, Q, relative amplitude, time delay, program material, listener hearing performance, loudspeaker directivity, and reverberation added during re...

Precision measurements on loudspeakers have been possible for some time now. Over the years, various views of their importance have developed as a result of accumulated experience and scientific investigation. A survey of the literature reveals areas of agreement and disagreement among workers. There is also evidence of geographic concentrations of...

With adequate attention to the details of experiment design and the selection of participants, listening tests on loudspeakers yielded sound-quality ratings that were both reliable and repeatable. Certain listeners differed in the consistency of their ratings and in the ratings themselves. These differences correlated with both hearing threshold le...

Measurements notwithstanding, listening tests remain the final arbiter of sound quality available from audio system components. The acoustical properties of the listening room and the locations of loudspeakers and listeners are significant factors in the results of such listening tests. Previous attempts to reach international agreement on standard...

Under certain conditions of acoustic stimulation, a listener may perceive a soundimage that is localized within the head. Different authors have attributed such in‐head localizations to (a) a static relationship between head position and components of the acoustic signal at the two ears, (b) abnormal acoustic‐impedance loading of the middle ear, (c...

When localizing sounds in a free‐field environment, listeners frequently confuse front and back. Careful study of these front‐back reversals reveals a dependence on factors other than the lack of a reverberant sound field. In the experiments described here, median‐plane localizations were produced by single and symmetrically disposed pairs of louds...

Experiments in free‐field localization where head movements are restricted have revealed that complex in‐head and external localizations frequently occur. The in‐head localization may be total (including all of the sound) or partial, in which case part of the sound is localized somewhere in the space around the listener. The externalized sound may...

Experimental results relating to the nature of acoustic images arising from binaural, repetitive, wide‐band acoustic transients are reported. In addition to the tonal harmonic images that may be identified in certain circumstances, there appear to be two dominant images of impulsive character. The latter images appear to be associated with neural a...

Lateralization-judgment trajectories with interaural time delay of acoustic images arising binaurally are reported for certain multicomponent signals such as multiple tones and repetitive transients. It is shown that certain multiple sound images simultaneously perceived may be independently lateralized and the characteristic judgment trajectories...