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In present study, subjective Chinese Mandarin word recognitions were carried out by 10 elderly listeners aged more than 60 years old in three rooms of a nursing house under the different reverberation time (RT), different signal-to-noise ratio (SNR) and different azimuth of noise conditions. The results showed that word recognition scores of the elderly increased with the increase of SNR and the spatial separation azimuth between speech and noise, and decreased with the increase of RT. The improvements of word recognition scores for spatial separation azimuth between speech and noise from 0° to 45° were more than those from 45° to 90° in all three rooms for the elderly. There was a great difference in the word recognition scores of hearing impairment elderly and normal hearing elderly under low SNR conditions and the difference decreased with the increase of SNR. The difference in the word recognition scores between hearing impairment participants and normal hearing participants also became smaller when the target speech and noise was spatially separated.

Snoring is an important characteristic of obstructive sleep apnea-hypopnea syndrome (OSAHS). Snoring sound can be used to develop a non-invasive approach for automatically screening OSAHS. In this paper, a snoring detection algorithm based on acoustic features and the XGBoost was proposed. The Fisher Ratio (FR) method was used for feature selection and the 23-dimensional feature set was extracted from the original 58-dimensional feature to reduce computational complexity. A variety of training and test data split methods were used to evaluate the performance of the proposed model. In addition, the proposed method was compared with the deep learning method on the independent subjects training set and test set. The accuracy of the reduced feature set by the proposed model was 87.22% and the deep learning model 87.26% on independent subjects training set and test set, the prediction time of the deep learning model on the test set was around 238 ms, the prediction time of XGBoost was around 58 ms, and the computing efficiency of XGBoost is higher than that of the deep learning model. The results show that the proposed method achieves a good balance between computational cost and performance. These results provide an important method for fast and real-time classification and evaluation of snoring for OSAHS.

62 rooms including living rooms, common rooms and dining rooms in 11 elderly care facilities had been measured, and some objective acoustical parameters in these rooms were measured such as background noise level (BNL) and reverberation time (RT). The range of BNL in 62 rooms was from 26.8 dBA to 67.2 dBA, and the mean BNL was 41.3 dBA and the standard deviation (SD) was 10.1 dBA. In these rooms, the averaged BNL in the living rooms was lower than those in the common rooms and the dining rooms, while the dining rooms had the highest averaged BNL. The RT in 500–4000 Hz octave bands, early-to-late sound ratio (C50) in 500–4000 Hz octave bands and speech transmission index (STI) in these rooms were 0.36–1.86 s, −4.48 to 9.67 dB and 0.47–0.81, respectively. Their mean values were 0.94 s, 1.73 dB and 0.64, and the SD were 0.40 s, 3.09 dB and 0.09, respectively. For all these measured rooms, the living room had a relatively short RT with a good speech intelligibility, while the dining room had a long RT with a fair speech intelligibility. To provide the elderly people with a good speech communication environment, some sound absorption and insulation treatment measures should be taken for the long RT and high BNL in the rooms of the elderly care facilities to reduce the BNL and RT and improve the speech intelligibility in these rooms.

The background noise and teacher’s teaching speech levels were measured in classrooms of Chinese elementary schools during class time in two conditions of using or without using sound reinforcement system (SRS). The ranges, mean values and standard deviations of the measurement data are reported and analyzed. It is found that in the condition of without using SRS, the relationship between the background and teaching levels satisfies the lambert effect quite well, while in the other condition of using SRS, this effect does not hold. Differences of background noise level and thus teaching level seem to be found between different courses but not be found between genders of the teachers. Finally, the background noise level is observed generally higher in classrooms of junior grades than the senior, and so is the teaching level.

The previous study had investigated the students’ speech perceptions in two primary school classrooms with similar reverberation time and found that the speech intelligibility in a classroom was better than that in other one. It is speculated that due to difference in the improvement in low frequency reverberation. In this study, the reverberation time and speech transmission index were obtained and compared from these two classrooms by simulated. The subjective Chinese speech intelligibility was evaluated through simulated binaural room impulse responses. The effect of low frequency reverberation on Chinese speech intelligibility in two classrooms was discussed. The result shows that improving the low frequency characteristic of reverberation time can be helpful to improve the Chinese speech intelligibility in classroom.

The elderly is more vulnerable to the detrimental effects of noise and reverberation. In the study, five simulated binaural room impulse responses with different reverberation time (RT) were convolved with test speech signals and background noise. Speech reception threshold (SRT) test was conducted on 22 elderly with different hearing levels (HLs) under different RT and background noise level (BNL) conditions. The results show that the SRT increases with the increase of age and deterioration of HL. The elderly have higher SRT than young adults. There is a high linear correlation between SRT and RT in different age groups and HL groups. Under 40 dBA and 55 dBA BNL conditions, the slope of linear fitting relationship between SRT and RT increases with the increase of age, and increases with the increase of pure tone average auditory. It also shows that the difference between different groups increases with the increase of RT. Under the same RT condition, the SRT in 40 dBA BNL is higher than that in 55 dBA BNL. However, the actual needed speech sound pressure level in 40 dBA BNL to obtain the same speech intelligibility is lower than that in 55 dBA BNL. It is more beneficial to improve the speech intelligibility of the elderly under a lower BNL condition with a sufficient sound pressure level. The architects should take reasonable acoustical measures to reduce the BNL and RT to improve the speech communication of the elderly in rooms.

Chinese word recognition (CWR) test was conducted by grades 3 and 5 children under the different conditions of reverberation time (RT), background noise level (BNL) and speech sound pressure level (SSPL) in three primary-school classrooms. The CWR scores and signal to noise ratios (SNRs) have been obtained at listening positions. Results show that the CWR score for grades 3 and 5 children increases with increase of SSPL, decrease of RT or increase of age, but it decreases with increase of BNL under the same conditions. For a mixed noise of 56 dBA (speech-spectrum-like noise and ambient noise), the CWR scores in the classroom for grades 3 and 5 children reach a peak at SNR of 15–20 dBA under the same RT and age of children condition. For the natural ambient noise, the CWR score for grades 3 and 5 children gradually increases with increase of the SNR. The high SSPL could not guarantee good CWR for children in classroom, which also depends on RT and BNL in classroom. When the classroom has long RT or high BNL, the increase of SSPL would not be necessarily to achieve better CWR. The novelty of the present study is to further evaluate and confirm the results under environments of real classrooms (not simulated room in laboratory).

Objective acoustical indices and subjective speech perception of students were investigated and compared in two different classrooms before and after an acoustical treatment. The treatment in the present study refers to the installation of sound absorption materials on the ceilings in two primary school classrooms. The results showed that the reverberation time after acoustical treatment was reduced, while the early-to-late sound ratio and the speech transmission index were improved. The subjective speech intelligibility in classrooms was also enhanced. Subjective survey showed that most of the students preferred learning in the classrooms after acoustical treatment. They reported that higher concentration is because the speeches of the teachers were much clear in the treated classroom. However, subjective speech perception of the students has some discrepancies between the two classrooms. The perception of the students in Classroom A was better than that in Classroom B. Sixty-two percent (61.9%) of the students prefer to study in the classroom A after acoustical treatment, but only 46.3% of the students prefer to study in the Classroom B. Results show that exceeding low-frequency reverberation in the classroom may significantly mask speech signals and have effect on the student’s speech perception in classroom, even though the traditional criteria of RT and C50 at mid-frequencies are similar.

In contrast to young adults with the normal hearing ability, most of the elderly can difficultly hear the speech signals in an unfavorable noisy and reverberant environment. In this paper, the effect of noise and reverberation in a room environment on the Chinese speech intelligibility of elderly (60–69 years old persons) and young adults with the normal hearing ability at different reverberation time (RT), background noise level (BNL), and signal-to-noise ratio (SNR) is investigated by using the auralization method. The results show that the speech intelligibility scores of Chinese elderly and young adults decrease with the increase in RT but increase with the increase in SNR. The obtained speech intelligibility scores of the young adults are higher than those of the elderly under the same test conditions. The speech intelligibility scores of the elderly are poorer than those of the young adults at high BNL, long RT, and low SNR. Namely, it is found that the elderly are more sensitive to the changes in reverberation case and reverberation plus noise case than the young adults. Moreover, the difference in the speech intelligibility scores between the elderly and young adults decreases with the decrease in the BNL. Lastly, it is shown that a low BNL is beneficial for improving the Chinese speech intelligibility of the elderly in a noisy and reverberant room environment.

In this article, objective acoustic parameters and students’ subjective responses were compared before and after an acoustic treatment in an elementary-school classroom. Acoustic treatment was done by installing sound absorption materials on the ceiling of the classroom for control of sound reverberation. The effects of reverberation time on children’s speech recognition have also been investigated. Results show that (1) the objective acoustic parameters in the classroom were obviously improved; (2) the subjective loudness of different types of noise sources, that students experienced in the classroom, were reduced; and (3) the speech intelligibility was significantly improved in the classroom after the acoustic treatment.

Subjective Chinese speech intelligibility was evaluated by using three sources with different directional patterns: an omnidirectional source, a source with similar directivity of a human speaker, and a human speaker source in both real and virtual rectangular rooms with different reverberation times. The result shows that subjective Chinese speech intelligibility scores exhibit statistical differences under different source conditions. Speech intelligibility scores obtained by using an omnidirectional source are lower than those obtained by using the other two sources. Therefore, the use of omnidirectional sources will undermine speech intelligibility compared with real human speech in rooms. Subjective Chinese speech intelligibility obtained from virtual rooms using auralization is basically similar to that obtained in real rooms under different source directivity conditions. Using the auralization technique enables the proper evaluation of subjective Chinese speech intelligibility with different directional sources.

Subjective speech intelligibility can be assessed by speech recorded in an anechoic chamber and then convolved with room impulse responses that can be created by acoustic simulation. The speech intelligibility (SI) assessment based on auralization was validated in three rooms. The articulation scores obtained from simulated sound field were compared with the ones from measured sound field and from direct listening in rooms. Results show that the speech intelligibility prediction based on auralization technique with simulated binaural room impulse responses (BRIRs) is in agreement with reality and results from measured BRIRs. When this technique is used with simulated and measured monaural room impulse responses (MRIRs), the predicted results underestimate the reality. It has been shown that auralization technique with simulated BRIRs is capable of assessing subjective speech intelligibility of listening positions in the room.