School teachers have an elevated risk of voice problems due to the vocal demands in the workplace. This manuscript presents the results of three studies investigating teachers’ voice use at work. In the first study, 57 teachers were observed for 2 weeks (waking hours) to compare how they used their voice in the school environment and in non-school environments. In a second study, 45 participants performed a short vocal task in two different rooms: a variable acoustic room and an anechoic chamber. Subjects were taken back and forth between the two rooms. Each time they entered the variable acoustics room, the reverberation time and/or the background noise condition had been modified. In this latter study, subjects responded to questions about their vocal comfort and their perception of changes in the acoustic environment. In a third study, 20 untrained vocalists performed a simple vocal task in the following conditions: with and without background babble and with and without transparent plexiglass shields to increase the first reflection. Relationships were examined between [1] the results for the room acoustic parameters; [2] the subjects’ perception of the room; and [3] the recorded speech acoustic. Several differences between male and female subjects were found; some of those differences held for each room condition (at school vs. not at school, reverberation level, noise level, and early reflection).

Measurements of musical instruments in an anechoic chamber at Brigham Young University are yielding high-resolution directivity data and balloon plots that may be analyzed and visualized as functions of time or frequency. Historically, room acoustics calculations involving directivity of sound sources have relied on well-defined radiation characteristics including principal radiation axes, directivity factors, beamwidths, etc. In recent times, room simulation software packages have incorporated more comprehensive steady state directivity data for loudspeakers that vary as functions of proportional frequency bands. However, in contrast to loudspeakers, many musical instruments have directivity patterns that are not well defined and that may vary more erratically as functions of pitch or other musical characteristics. This presentation explores the measured directivity properties of a few musical instruments and discusses how they might be encapsulated and incorporated into predictive room acoustics calculations.

School teachers are known to have an elevated risk of voice problems due to the vocal demands in their work environments. Forty-five participants (20 females, 25 males, 7 elementary school teachers, and 38 college-age adults) performed a short vocal task in two different rooms: a variable-acoustics room and an anechoic chamber. The subjects were taken back and forth between the two rooms using a deception protocol. Each time they entered the variable-acoustics room, the acoustical characteristics (two background noise conditions and two reverberation conditions) had been changed without a visual appearance of change. Analysis was conducted on recorded second and third sentences of the first paragraph of the Rainbow Passage. Results revealed that differences in response to reverberation was gender specific. Additionally, school teachers seemed to be more susceptible to the noise condition.

Forty-five subjects performed a short vocal task in two different rooms: a variable-acoustics room and an anechoic chamber. The subjects were taken back and forth between the two rooms using a deception protocol. Each time they entered the variable-acoustics room, its acoustical characteristics had been changed without a change in visual appearance. The changing characteristics involved two background noise conditions and two reverberation conditions. Subjects responded to questions about their comfort and perception of the environmental changes. Analysis was performed on the second and third sentences of the rainbow passage. Objective acoustical metrics and perceptual responses were compared for the different settings. In contrast to males, females raised their fundamental frequency (F0) in concert with their raised vocal levels in response to changes in both loudness and reverberation. A high correlation existed between pitch strength and F0. Factor analysis also revealed that F0 and vocal level were more correlated in females than males.

A real-time convolution system has been developed to quickly manipulate the auditory experiences of human subjects. The system is used to study perceptions of self-generated speech and music, and responses of talkers and musicians to varying acoustical conditions. It allows talkers in an anechoic environment to experience simulated room responses excited by their own voices. While their direct sound travels directly to their ears, they hear convolved room responses via specialized headphones spaced away from their heads. This presentation discusses the system’s development, as well as its objective and subjective validations. Several existing rooms were modeled using EASE. Oral-binaural room impulse responses (OBRIRs) from these models were generated and implemented with the convolution system. Binaural recordings and measurements from the rooms were also made using a G.R.A.S. KEMAR mannequin. Objective comparisons of the OBRIRs from the measurements and simulations were explored in the investigation. Subjective evaluations of auralizations made from the OBRIR measurements and simulations, and binaural recordings, followed from A/B listening and speaking tests. In the latter, participants spoke in the various simulated acoustical environments and compared and rated the effects of each experience.