Differential Effects of Task-Irrelevant Monaural and Binaural Classroom Scenarios on Children's and Adults' Speech Perception, Listening Comprehension, and Visual-Verbal Short-Term Memory.

Most studies investigating the effects of environmental noise on children's cognitive performance examine the impact of monaural noise (i.e., same signal to both ears), oversimplifying multiple aspects of binaural hearing (i.e., adequately reproducing interaural differences and spatial information). In the current study, the effects of a realistic classroom-noise scenario presented either monaurally or binaurally on tasks requiring processing of auditory and visually presented information were analyzed in children and adults. In Experiment 1, across age groups, word identification was more impaired by monaural than by binaural classroom noise, whereas listening comprehension (acting out oral instructions) was equally impaired in both noise conditions. In both tasks, children were more affected than adults. Disturbance ratings were unrelated to the actual performance decrements. Experiment 2 revealed detrimental effects of classroom noise on short-term memory (serial recall of words presented pictorially), which did not differ with age or presentation mode (monaural vs. binaural). The present results add to the evidence for detrimental effects of noise on speech perception and cognitive performance, and their interactions with age, using a realistic classroom-noise scenario. Binaural simulations of real-world auditory environments can improve the external validity of studies on the impact of noise on children's and adults' learning.

Effect of voice support level and spectrum on conversational speech.

One's own voice (autophony) is transmitted to the ears as direct airborne sound, bone conduction, and indirect airborne sound from reflections characterized by overall gain and spectro-temporal features. This study investigates how the spectral profile and gain of simulated indirect airborne sound, quantified as voice support (STV), affect the speaking voice of talkers. Pairs of participants performed a conversation elicitation task in anechoic conditions. The indirect airborne sound was provided in real-time via open headphones that maintain the direct airborne transmission path. Experimental conditions included high-pass, low-pass, and all-pass versions of STV, each presented at three overall gains, and a Baseline condition with no electroacoustic contribution to STV. The results show an overall speech level reduction of 0.22 dB for every additional dB of speech-weighted STV, i.e., a -0.22 dB/dB slope. There was some effect of STV spectrum on speech: slope for the high-pass condition was steeper (statistically significant) and significantly different from the all-pass slope; spectral balance (2-4 kHz vs 0-2 kHz) of speech showed an interaction effect between gender and experimental conditions. This paper's findings may inform acoustic treatments in environments where overall sound reduction is of interest for favorable ergonomics and occupational health for voice professionals.

Chamber musicians' acoustic impressions of auditorium stages: Relation to spatial distribution of early reflections and other parameters.

Characterizing stage acoustics using objective parameters has seen some recent resurgence-several studies have noted the importance of the directionality of early stage reflections to musicians, which is not adequately represented using existing omnidirectional stage-support parameters. This study examines the subjective impressions of 19 chamber musicians against omnidirectional [reverberation time, early and late support (STEarly, STLate), etc.], and proposed spatially-defined parameters (TH and TS), along with simple ratios of stage dimensions derived from measurements on eight purpose-built stages. TH is a ratio of early energy from "above" to that from the "horizontal," while TS relates energy from above to that from the "sides" of the stage. Robust mixed-effects analyses showed that the musicians' overall acoustic impression ratings are predicted (i) by TH within a linear model; (ii) by TH × STEarly,TH × STLate, and TS × STEarly,TS × STLate; (iii) by STEarly, STLate each within parabolic models; and (iv) by several architectural parameters' linear and parabolic models. These findings reinforce recent studies of spatially-defined parameters to more fully account for the subtleties of onstage sound fields. Some simple design recommendations are presented, although future studies are needed to confirm these findings/recommendations for a wider range of auditorium stages.

Autophonic Loudness of Singers in Simulated Room Acoustic Environments.

OBJECTIVES: This paper aims to study the effect of room acoustics and phonemes on the perception of loudness of one's own voice (autophonic loudness) for a group of trained singers. METHODS: For a set of five phonemes, 20 singers vocalized over several autophonic loudness ratios, while maintaining pitch constancy over extreme voice levels, within five simulated rooms. RESULTS: There were statistically significant differences in the slope of the autophonic loudness function (logarithm of autophonic loudness as a function of voice sound pressure level) for the five phonemes, with slopes ranging from 1.3 (/a:/) to 2.0 (/z/). There was no significant variation in the autophonic loudness function slopes with variations in room acoustics. The autophonic room response, which represents a systematic decrease in voice levels with increasing levels of room reflections, was also studied, with some evidence found in support. Overall, the average slope of the autophonic room response for the three corner vowels (/a:/, /i:/, and /u:/) was -1.4 for medium autophonic loudness. CONCLUSIONS: The findings relating to the slope of the autophonic loudness function are in agreement with the findings of previous studies where the sensorimotor mechanisms in regulating voice were shown to be more important in the perception of autophonic loudness than hearing of room acoustics. However, the role of room acoustics, in terms of the autophonic room response, is shown to be more complicated, requiring further inquiry. Overall, it is shown that autophonic loudness grows at more than twice the rate of loudness growth for sounds created outside the human body.

Assessing Linearity in the Loudness Envelope of the Messa di Voce Singing Exercise Through Acoustic Signal Analysis.

Messa di voce (MDV) is a singing exercise that involves sustaining a single pitch with a linear change in loudness from silence to maximum intensity (the crescendo part) and back to silence again (the decrescendo part), with time symmetry between the two parts. Previous studies have used the sound pressure level (SPL, in decibels) of a singer's voice to measure loudness, so as to assess the linearity of each part-an approach that has limitations due to loudness and SPL not being linearly related. This article studies the loudness envelope shapes of MDVs, comparing the SPL approach with approaches that are more closely related to human loudness perception. The MDVs were performed by a cohort of tertiary singing students, recorded six times (once per semester) over a period of 3 years. The loudness envelopes were derived for a typical audience listening position, and for listening to one's own singing, using three models: SPL, Stevens' power law-based model, and a computational loudness model. The effects on the envelope shape due to room acoustics (an important effect) and vibrato (minimal effect) were also considered. The results showed that the SPL model yielded a lower proportion of linear crescendi and decrescendi, compared with other models. The Stevens' power law-based model provided results similar to the more complicated computational loudness model. Longitudinally, there was no consistent trend in the shape of the MDV loudness envelope for the cohort although there were some individual singers who exhibited improvements in linearity.

Towards a method for loudness-based analysis of the sound of one's own voice.

This paper outlines the steps in objectively estimating the time-varying loudness of one's own voice in a room (i.e. autophonic loudness). Voice recordings, made with a near-mouth microphone, are converted to the sound that reaches the two eardrums of the talking (or singing)-listener by convolving them with the impulse responses from the mouth to the respective ears of an anthropomorphic head and torso. The influences of bone-conducted sound and room reflections are taken into account. These convolved recordings are then processed with a computational time-varying loudness model. The method is demonstrated by a short case study, and the results illustrate something of the benefit of loudness analysis over sound pressure level analysis for representing autophonic loudness.