Simplified expressions of uncertainty for single number quantities in ISO 3382-3 (2022).

The ISO 3382-3 (2022) standard defines single number quantities (SNQs) characterizing the spatial decay of speech (D2S, LpAS4m, rC) and of its intelligibility (rD). The standard assesses the accuracy of the measurement using a unique uncertainty value for each SNQ, relying on a round-robin test performed in a single office. To make this assessment more accurate, analytical expressions have been established by applying the law of propagation of uncertainty. These expressions, although precise, are too complex to be included in the standard. This work consists of their simplification, relying on 95 measurements conducted in 36 companies in France and Germany. First, the terms associated with distance measurement uncertainties were found to be negligible. Second, the estimation of the uncertainties of A-weighted speech levels and Speech Transmission Index, based on the measurements made at the workstations constituting the 95 paths, enabled further simplifications. Finally, simplified expressions turn out to be as accurate as the original expressions, and the estimated uncertainties are comparable to those reported by Yadav et al. (2019). If a unique value of uncertainty is to be retained for each SNQ, this study suggests 0.6 dB for D2S and LpAS4m, 7% for rC, and 10% for rD.

Vocal and semantic cues for the segregation of long concurrent speech stimuli in diotic and dichotic listening-The Long-SWoRD test.

It is not always easy to follow a conversation in a noisy environment. To distinguish between two speakers, a listener must mobilize many perceptual and cognitive processes to maintain attention on a target voice and avoid shifting attention to the background noise. The development of an intelligibility task with long stimuli-the Long-SWoRD test-is introduced. This protocol allows participants to fully benefit from the cognitive resources, such as semantic knowledge, to separate two talkers in a realistic listening environment. Moreover, this task also provides the experimenters with a means to infer fluctuations in auditory selective attention. Two experiments document the performance of normal-hearing listeners in situations where the perceptual separability of the competing voices ranges from easy to hard using a combination of voice and binaural cues. The results show a strong effect of voice differences when the voices are presented diotically. In addition, analyzing the influence of the semantic context on the pattern of responses indicates that the semantic information induces a response bias in situations where the competing voices are distinguishable and indistinguishable from one another.

Assessment of helicopter passengers' vibration discomfort: proposal for improvement of the ISO 2631-1 standard.

High levels of vibration exist in helicopters and manufacturers are seeking to quantify vibration discomfort. They use the ISO 2631-1 standard, proposed for all types of transport. This study aimed to verify the validity of this index in the specific case of helicopters. Perception tests were carried out in the laboratory. Volunteers assessed the discomfort of vibratory stimuli on test benches generating vertical and triaxial vibrations. Foot, seat, and backrest accelerations were measured for each participant according to each stimulus. The ISO 2631-1 comfort indices were then compared with the evaluations given by the participants. The results showed that the standard provided a good estimate of discomfort. However, it lacks precision in estimating the discomfort of stimuli which include amplitude modulations, as can happen in helicopters. A new discomfort index is proposed based on ISO 2631-1 and allows better prediction of subjective assessments. Practitioner Summary: An improved index based on ISO 2631-1 standard is proposed to estimate helicopter vibratory discomfort for seated passengers. It takes into account the amplitude modulations that can appear at low frequencies in helicopters. This modification allowed a significant improvement of the accuracy of ISO 2631-1 for such stimuli.

Behavioral Account of Attended Stream Enhances Neural Tracking.

During the past decade, several studies have identified electroencephalographic (EEG) correlates of selective auditory attention to speech. In these studies, typically, listeners are instructed to focus on one of two concurrent speech streams (the "target"), while ignoring the other (the "masker"). EEG signals are recorded while participants are performing this task, and subsequently analyzed to recover the attended stream. An assumption often made in these studies is that the participant's attention can remain focused on the target throughout the test. To check this assumption, and assess when a participant's attention in a concurrent speech listening task was directed toward the target, the masker, or neither, we designed a behavioral listen-then-recall task (the Long-SWoRD test). After listening to two simultaneous short stories, participants had to identify keywords from the target story, randomly interspersed among words from the masker story and words from neither story, on a computer screen. To modulate task difficulty, and hence, the likelihood of attentional switches, masker stories were originally uttered by the same talker as the target stories. The masker voice parameters were then manipulated to parametrically control the similarity of the two streams, from clearly dissimilar to almost identical. While participants listened to the stories, EEG signals were measured and subsequently, analyzed using a temporal response function (TRF) model to reconstruct the speech stimuli. Responses in the behavioral recall task were used to infer, retrospectively, when attention was directed toward the target, the masker, or neither. During the model-training phase, the results of these behavioral-data-driven inferences were used as inputs to the model in addition to the EEG signals, to determine if this additional information would improve stimulus reconstruction accuracy, relative to performance of models trained under the assumption that the listener's attention was unwaveringly focused on the target. Results from 21 participants show that information regarding the actual - as opposed to, assumed - attentional focus can be used advantageously during model training, to enhance subsequent (test phase) accuracy of auditory stimulus-reconstruction based on EEG signals. This is the case, especially, in challenging listening situations, where the participants' attention is less likely to remain focused entirely on the target talker. In situations where the two competing voices are clearly distinct and easily separated perceptually, the assumption that listeners are able to stay focused on the target is reasonable. The behavioral recall protocol introduced here provides experimenters with a means to behaviorally track fluctuations in auditory selective attention, including, in combined behavioral/neurophysiological studies.

Two laboratory methods of assessing annoyance due to railway noise and vibration.

In laboratory experiments, total annoyance due to combined noise and vibration and partial annoyances due to each source in the presence of the other can be assessed in two ways: during separate sessions dedicated to the evaluation of each kind of annoyance, and during the same session. This letter examines the difference between annoyance responses provided by the two methods. No differences were found between partial (respectively, total) annoyance responses measured during separate sessions and those measured during the same session. The latter procedure allows reducing the number of stimuli to which the participants are subjected.