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Noise and intelligibility measurements were taken in dozens of classrooms at approximately every-meter resolution and are presented as heat maps. In doing so we hope to determine (1) the largest (and loudest) classrooms that do not require loudspeaker speech amplification and (2) the radius of muddled intelligibility circumscribed around noise sources such as air diffusers and fan coil units.

Concert hall sound fields were simulated by architecture students and anechoic recordings were convolved to create auralizations in those simulated performance spaces. Then an architectural feature was altered digitally and a second track was auralized. College music students were recruited, tested for hearing loss, and brought to a low-reverberance room with a spatial sound array of 28 mounted speakers. They were asked to identify which of the two simulated tracks they prefer. We compared simulated performance spaces: (1) with four tiers of balconies vs with one tier of balcony; (2) with an over-stage canopy vs without a canopy; (3) with separate balcony boxes vs with a continuous balcony not fragmented by box walls; and (4) with a higher scattering coefficient vs a lower scattering coefficient. Those in the audience will be invited to judge preference between the tracks for themselves. The study will be framed by the extraordinary career arc of Bert Kinzey who engaged architecture students in the study ...

Acoustically absorbent materials are generally “fuzzy.” This texture converts sound energy into heat through friction, thereby reducing the amount of sound that reflects back into the room.[1] In contrast, this research explores smooth surface alternatives to speech-frequency sound absorption by retracing the efforts of Wallace C. Sabine and his partner, architect and thin-structural-tile builder Raphael Guastavino. The two, each a luminary in his respective field at the time, teamed up in the early 1900s to manufacture sound absorbent ceramic tiles. After attempting to recreate and test the Sabine-Guastavino tiles, we sought to improve upon the concept of a porous, fire-proof, and acoustically absorbent tile to include a smooth surface that is easily sanitized to be used in facilities like child care centers, schools, and hospitals. While there are materials on the market that provide a smooth surface of micro-pores that open to a “fuzzy” material behind the surface, this novel material would be a contin...

Time differences of arrival (TDOA) are often sufficient data for localization of a sound source with a sensor array. We consider the problem of localizing multiple impulsive sound sources that occur on a military installation having live-fire training exercises, using a dozen or more noise monitors as a large array. In this setup, though, sounds from multiple events can arrive in different order at different monitors. When multiple sources are operating, ambiguous source-detection assignments degrade the localization estimates. By minimizing a global cost-function on the entire detection catalog, we resolve source-detection assignments and improve the localizations. We outline an estimator and show results with simulated data and field measurements.

A "real world" transmission loss (RWTL) chamber was recently added to the undergraduate acoustics program at Columbia College Chicago. It aims to demonstrate concepts of transmission loss to students, and to provide a "less-than-ideal" environment for construction evaluation prior to certified tests with full-size samples. Each side of the chamber can be used as either "send" or "receive," and both speaker and microphone placements are infinitely variable. The noise floor can also be adjusted to illustrate potential issues in field tests. Measurements are taken simultaneously from multiple positions, then averaged to yield TL values and an overall isolation rating. Given its construction, the chamber is not expected to produce results as per existing standards as its small size results in modal effects and non-diffuse conditions on both sides of the tested partition. This study's first goal was to better understand the performance limitations of the RWTL chamber by conducting a thorough evaluation of its ...

What is the largest classroom that will support unamplified communication? What design attributes and acoustical conditions contribute to speech intelligibility, and how much should each design attribute be weighted when predicting speech transmission index (STI)? This line of inquiry aims to correlate room design and mechanical equipment (HVAC) design to speech intelligibility (STI) in university lecture rooms. It seeks to link the STI of classrooms at Virginia Tech to ambient noise levels, reverberation time, impulse response characteristics, room volume, number of seats, distance to nearest HVAC terminal device, receiver location, and speaker source power. Ambient noise measurements and STI will be mapped on a 1 m x 1 m grid for a subset of the measured rooms to visualize the noise on the listener plane and better estimate the haptic component of signal-to-noise ratio in the spaces. The research also will explore quirks in the STI measurement itself, including differences between the direct and indirec...

The researchers share three studies in parametric, generative, and iterative architectural acoustics. (1) A real-time parametric model shapes a geometrically complex ceiling plane with grips in order to visualize first-order reflections so that early arriving strong reflections may be directed to the audience and late-arriving echoes may be avoided. (2) A ray-tracing software model pivots door openings so that a coupled volume concert hall can be calibrated to establish the “sweet spot” range of aperture sizes that are more likely to produce a double-sloped sound decay. (3) A custom-designed auralization software simulates sound transmission loss so that designers may hear the (relative) noise isolation of different assemblies.

Unattended and continuously running environmental noise monitoring systems can capture an intractable amount of data. The signals captured can include a multitude of sources (e.g., wind noise and anthropogenic noise sources) in addition to the environmental noise sources of interest (e.g., aircraft, vehicles, trains, and military weapons). In this presentation, we explore the use of machine-learning methods to effectively isolate and identify environmental noise sources captured on such a noise monitoring system. Specifically, we consider the use of both unsupervised (e.g., principle components analysis, clustering methods, and deep belief networks) and supervised (e.g., logistic regression, support vector machines, and neural networks) pattern-learning methods to derive the features of interest and classify the signals based on the obtained features. The generalization performance of each method is assessed using a dataset of over 120,000 human classified signals, and the strengths and weaknesses of each approach are discussed.

Impulse testing is used by industry professionals to test many parameters of room acoustics, including the energy decay, frequency response, time response, etc. Current testing software makes this process as streamlined as possible, but generally must be utilized in quiet environments to yield high signal-to-ratios and more precise results. However, many real world situations cannot conform to the necessary standards needed for reliable data. This study tests various methods of impulse responses in background noise environments in an attempt to find the most reliable procedure for spaces with a high ambient noise levels. Additionally, extreme situations will be evaluated and a method will be derived to correct for the systematic error attributed to high background noise levels.

A new, large-scale variable acoustics space has recently been added to the Audio Arts & Acoustics department at Columbia College Chicago. Built within the current Motion Capture studio, this facility will provide students and faculty the ability to perform tests in an acoustically controlled environment, without the influence of small-room effects. The construction involved the creation of nearly 300 2 in. x 2 in. reversible boxes: one side diffusive and the other absorptive. These line three full walls of the space at a height of 10 in., totaling ~1200 ft2 of acoustically adjustable surface area. This allows the room to convert from a very absorptive space, to one that is much more acoustically active. Multiple specular reflector panels are also available for the creation of “hot spots,” allowing for even more diverse applications. This study focused on the construction and initial testing of this innovative new space. To analyze the effectiveness of the additions, frequency, time, and reverberation responses for the entire room were sampled in a variety of configurations: fully absorptive, fully diffusive, empty, etc. These objective metrics were then analyzed against perceptual data to determine the correlation between what could be measured and what could be heard.