A study of the just noticeable difference of early decay time for symphonic halls.

The just noticeable differences (JNDs) of room acoustic parameters are important for the design of concert halls and, in general, research of room acoustics. Precise knowledge of JNDs helps the concert hall designer in assessing the impact that changes in the geometry or materials of the hall will have on its perceived acoustics. When designing a concert hall, creating an appropriate feeling of reverberance for the audience is of prime importance. The early decay time (EDT) parameter has proved to be a better predictor of the perception of reverberance than the classical reverberation time (T30), but no studies have been conducted to specifically determine the EDT JND. In the present study, the EDT JND was investigated for broadband conditions and assessed for individual frequency ranges. A subjective study was conducted with 26 subjects with musical training, in which 21 were considered reliable. The participants listened to orchestral music convolved with measured spatial room impulse responses from three concert halls. The stimuli were auralized in an anechoic chamber using third-order Ambisonic reproduction. The obtained values show that the JNDs for the broadband conditions are lower than those for the individual frequency ranges. The EDT JND for the broadband conditions was found to be approximately 18% of the EDT value.

I know that voice! Mothers' voices influence children's perceptions of emotional intensity.

The ability to interpret others' emotions is a critical skill for children's socioemotional functioning. Although research has emphasized facial emotion expressions, children are also constantly required to interpret vocal emotion expressed at or around them by individuals who are both familiar and unfamiliar to them. The current study examined how speaker familiarity, specific emotions, and the acoustic properties that comprise affective prosody influenced children's interpretations of emotional intensity. Participants were 51 7- and 8-year-olds presented with speech stimuli spoken in happy, angry, sad, and nonemotional prosodies by both each child's mother and another child's mother unfamiliar to the target child. Analyses indicated that children rated their own mothers as more intensely emotional compared with the unfamiliar mothers and that this effect was specific to angry and happy prosodies. Furthermore, the acoustic properties predicted children's emotional intensity ratings in different patterns for each emotion. The results are discussed in terms of the significance of the mother's voice in children's development of emotional understanding.

Sensitivity of the human auditory cortex and reward network to reverberant musical stimuli.

A room's acoustics can alter subjective impressions of music, including preference. However, little research has characterized the brain's response to room conditions. Functional magnetic resonance imaging (fMRI) was used to investigate the auditory and reward responses to concert hall stimuli. Before the fMRI testing, 18 participants rated their preferences to a solo-instrumental passage and an orchestral motif simulated in eight room acoustic conditions outside an MRI scanner to identify their most liked and disliked conditions. In the MRI, the most-liked (reverberation time, RT = 1.0-2.8 s) and most-disliked (RT = 7.2 s) conditions, along with the [anechoic and scrambled versions] anechoic and scrambled versions of the musical passages were presented. The auditory cortex was found to be sensitive to the temporal coherence of the stimuli as it exhibited stronger activations for simpler stimuli, i.e., the solo-instrumental and anechoic conditions, than for stimuli containing temporally incoherent auditory objects-the orchestral and reverberant conditions. In contrasts between liked and disliked reverberant stimuli, a reward response in the basal ganglia was detected in a region of interest analysis using a temporal derivative model of the hemodynamic response function. This response may indicate differences in preference between subtle variations in room acoustics applied to the same musical passage.

An investigation of listener envelopment utilizing a spherical microphone array and third-order ambisonics reproduction.

Listener envelopment (LEV), the sense of being surrounded by the sound field, is a perception that has been found to be related to the overall impression of a concert hall. The purpose of this study was to investigate the relationship between the perception of LEV and the direction and arrival time of energy from spatial room impulse responses (IRs). IRs were obtained in a 2000-seat concert hall using a 32-channel spherical microphone array and analyzed using a third-order plane wave decomposition. Additionally, the IRs were convolved with anechoic music and processed for third-order Ambisonic reproductions and presented to subjects over a 30-loudspeaker array. Instances were found in which the energy in the late sound field did not correlate with LEV ratings as well as energy in a 70-100 ms time window. Follow-up listening tests were conducted with hybrid IRs containing portions of an enveloping IR and an unenveloping IR with crossover times ranging from 40 to 140 ms. Additional hybrid IRs were studied wherein portions of the spatial IRs were collapsed into all frontal energy with crossover times ranging from 40 to 120 ms. The tests confirmed that much of the important LEV information exists in the early portion of these IRs.

Young children's neural processing of their mother's voice: An fMRI study.

In addition to semantic content, human speech carries paralinguistic information that conveys important social cues such as a speaker's identity. For young children, their own mothers' voice is one of the most salient vocal inputs in their daily environment. Indeed, qualities of mothers' voices are shown to contribute to children's social development. Our knowledge of how the mother's voice is processed at the neural level, however, is limited. This study investigated whether the voice of a mother modulates activation in the network of regions activated by the human voice in young children differently than the voice of an unfamiliar mother. We collected fMRI data from 32 typically developing 7- and 8-year-olds as they listened to natural speech produced by their mother and another child's mother. We used emotionally-varied natural speech stimuli to approximate the range of children's day-to-day experience. We individually-defined functional ROIs in children's voice-sensitive neural network and then independently investigated the extent to which activation in these regions is modulated by speaker identity. The bilateral posterior auditory cortex, superior temporal gyrus (STG), and inferior frontal gyrus (IFG) exhibit enhanced activation in response to the voice of one's own mother versus that of an unfamiliar mother. The findings indicate that children process the voice of their own mother uniquely, and pave the way for future studies of how social information processing contributes to the trajectory of child social development.

Effects of test method and participant musical training on preference ratings of stimuli with different reverberation times.

Selecting an appropriate listening test design for concert hall research depends on several factors, including listening test method and participant critical-listening experience. Although expert listeners afford more reliable data, their perceptions may not be broadly representative. The present paper contains two studies that examined the validity and reliability of the data obtained from two listening test methods, a successive and a comparative method, and two types of participants, musicians and non-musicians. Participants rated their overall preference of auralizations generated from eight concert hall conditions with a range of reverberation times (0.0-7.2 s). Study 1, with 34 participants, assessed the two methods. The comparative method yielded similar results and reliability as the successive method. Additionally, the comparative method was rated as less difficult and more preferable. For study 2, an additional 37 participants rated the stimuli using the comparative method only. An analysis of variance of the responses from both studies revealed that musicians are better than non-musicians at discerning their preferences across stimuli. This result was confirmed with a k-means clustering analysis on the entire dataset that revealed five preference groups. Four groups exhibited clear preferences to the stimuli, while the fifth group, predominantly comprising non-musicians, demonstrated no clear preference.

Reverberation negatively impacts musical sound quality for cochlear implant users.

OBJECTIVE: Satisfactory musical sound quality remains a challenge for many cochlear implant (CI) users. In particular, questionnaires completed by CI users suggest that reverberation due to room acoustics can negatively impact their music listening experience. The objective of this study was to more specifically characterize of the effect of reverberation on musical sound quality in CI users, normal hearing (NH) non-musicians, and NH musicians using a previously designed assessment method, called Cochlear Implant-MUltiple Stimulus with Hidden Reference and Anchor (CI-MUSHRA). METHODS: In this method, listeners were randomly presented with an anechoic musical segment and five-versions of this segment in which increasing amounts of reverberation were artificially added. Participants listened to the six reverberation versions and provided sound quality ratings between 0 (very poor) and 100 (excellent). RESULTS: Results demonstrated that on average CI users and NH non-musicians preferred the sound quality of anechoic versions to more reverberant versions. In comparison, NH musicians could be delineated into those who preferred the sound quality of anechoic pieces and those who preferred pieces with some reverberation. DISCUSSION/CONCLUSION: This is the first study, to our knowledge, to objectively compare the effects of reverberation on musical sound quality ratings in CI users. These results suggest that musical sound quality for CI users can be improved by non-reverberant listening conditions and musical stimuli in which reverberation is removed.

The effects of different test methods on the just noticeable difference of clarity index for music.

The just noticeable differences (JNDs) of room acoustics metrics are necessary for research and design of performing arts venues. The goal of this work was to evaluate the effects of different testing methods on the measured JND of clarity index for music (C80). An initial study was conducted to verify the findings of other published works that the C80 JND is approximately 1 dB, as currently listed in ISO 3382:2009 (International Organization for Standardization, Switzerland, 2009), however, the results suggested a higher value. In the second study, the effects of using two variations of the method of constant stimuli were examined, where one variation required the subjects to evaluate the pair of signals by listening to each of them in their entirety, while the second approach allowed the participants to switch back and forth in real-time. More consistent results were obtained with the latter variation and the results indicated a C80 JND greater than 1 dB. In the final study, an extensive training period using the first variation was required, based on the second study, and the data were collected using the second variation. The analysis revealed that for the conditions used in this study (concert hall and chamber music hall) that the C80 JND is approximately 3 dB.