PROCEEDINGS of the23rd International Congress on Acoustics
9 to 13 September 2019 in Aachen, Germany

A pilot study of the relationship between mandarin Chinese wordand sentence recognition for the elderly
Jianxin PENG1; Jiazhong ZENG2; Jiaming LIU3;South China University of Technology, China

ABSTRACTIn present study, the simulated binaural room impulse responses with different reverberation times (RTs),
were convolved with the test word and sentence signals, and noise signal, and then reproduced by headphone.
The subjective word and sentence recognition scores for elderly under different signal-to-noise ratio and RT
were obtained. The results show that the shorter the RT, the higher the scores of word recognition andsentence recognition for the elderly. The higher the signal-to-noise ratio, the higher the scores of word
recognition and sentence recognition. There is high correlation between the scores of word recognition andsentence recognition for the elderly.
Keywords: Reverberation time, Signal-to-noise ratio, Word recognition, Sentence recognition, Ederly

1. INTRODUCTION
The auditory function of the elderly is gradually degenerative with the increase of age, and theirhearing sensitivity and speech comprehension ability in noisy environment are gradually reduced.
Compared with young adults with normal hearing, most of the elderly are difficult to hea r speech
signals in unfavorable listening environment (1-3). Nabelek and Robinson (4) pointed out that speech
intelligibility scores obtained at different reverberation times (RTs) required 10-20 dB sound pressurelevels higher for old adults than in young adults through Modified Rhyme Test. Helfer and Huntley (5)studied the recognition of English consonants for the elderly in reverberation and noise. The subjects
were divided into the elderly with impaired hearing, the elderly with slight hearing loss and the young
normal hearing. The results show that the elderly had a considerable barrier to speech understanding in
the non-ideal auditory environment. A study by Sato (6) showed that speech intelligibility scores of theolder listeners were 25% lower than those of young adults for a series of speech intelligibility test
involving 20 younger and 20 older subjects. He pointed out that the effect of this difference was equal
to the 5 dB increase of ambient noise. These studies demonstrated that the auditory fu nction of elderly
are gradually impaired when the elderly get older and the elderly need a higher speech intelligibility.
STI was first proposed by Houtgast and Steeneken (7) and combined the effects of reverberationand noise on speech intelligibility in rooms into an objective parameter, which is used by many
researchers and is good at predicting the speech intelligibility in room. Peng and Zhang (8, 9)
conducted a subjective listening experiment on the correlation between Chinese speech intelligibilityand STI in room. The results show that STI can predict and evaluate the speech intelligibility in roomwell.
In this work, subjective evaluation of Chinese the word and sentence recognition under different
reverberation and signal-to-noise ratio (SNR) conditions were conducted. The the word and sentence
recognition in different acoustical environments were analyzed and compared. The relationshipbetween the word and sentence recognition scores was also analyzed. The aims are to explore thespeech communication effect of elderly in different reverberation and SNR conditions.

1

phjxpeng@163.com
zczjz@scut.edu.cn
3942807917@qq.com
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2. METHODS
2.1 Rooms and sound fields
Six rooms were modelled using ODEON. In each model, a source and a receiver (listening position)
were set. The listening position in each room was located outside of the reverberation radius of theroom and the minimum distance was 5.2 m and the maximum distance was 12.6 m between the source
and listening position among these six listening positions. At each listening position, the RT and abinaural room impulse response were obtained by ODEON acoustical simulation through adjusted theabsorption material in the room. The RT in 500-1000Hz octave frequency band at these six listeningpositions were given in Table 1. The room No .1 is the case in the anechoic chamber with noreverberation.
Table 1 –Objective acoustical parameters
Room No.

RT /sSTINo reverberation

12

0.4

0.61

3

0.6

0.57

4

1.0

0.52

5

1.5

0.46

6

2.2

0.44

7

5.2

0.37

2.2 Word and sentence recognition test
The word recognition test conducted by using Mandarin Chinese test word lists as specified by GB4959 (10). The test uses 25 five-word rows of similar-sounding Chinese monosyllabic words and issimilar to modified rhyme test of English. The five words in each row are randomly arranged and diffe r
only in the initial consonant sound (for example, hao, sao, gao, zao, kao). Fifteen word lists were
derived from five basic word lists. One list is used for students to practice, the rest fourteen word lists
are used for the test. The test word in carrier phrase is “The × row reads – ”. The “×” stands for row
number and “—” stands for a test word. On the other hand, Chinese Mandarin Hearing in Noise Test
(MHINT) (11) is used for the sentence recognition test. Fifteen sentence lists are used in the test. Onelist is used for students to practice, the rest fourteen lists are used for the test. Every list contains 10sentences. And each sentence is composed of 10 target words, for example, “଑୭⌫஄ৄனᡴධ෩૔(This team enters the finals at last)” . All word and sentence lists are recorded at the rate of 4.0 words
per second in an anechoic chamber by using an omni-directional precision microphone at a distance of
0.5m from the male speaker. The recording is edited by CoolEdit Pro. A ten -second (/thirty second)
interval of silence between two adjacent carrier sentences (/test sentence) allowing listeners to markthe test word (/ write the test sentence) which he (/she) heard on the test paper has been inserted.
Based on the average speech spectrum from test word and sentence signals, the corresponding
speech-shaped noises are selected for the tests. The SNR was made equal for all selected frequency
bands using speech-shaped noise with a frequency spectrum equivalent to the long -term speech
spectrum. Since a speech-shaped noise with a frequency spectrum equivalent to the long-term speech
spectrum was used, the SNR was approximately equal for all selected frequency bands (12). All thenoise, Chinese word and sentence test signal recorded in the anechoic chamber were convolved withthe binaural room impulse response respectively, then mixed according to a certain SNR ( -5dBA and5dBA), and then reproduced through the Sennheiser HD580 headphone for the subjective Word andsentence recognition evaluation..
2.3 Participants
Six elderly aged more than 60 years old who could hear and speak Mandarin were randomly
selected to participate in the test. The old participants received a few minutes of instruction before thetest. There was an interval of more than seven days after the participants performed a test in order toavoid their remembering the word lists. Presented by playback system in closed -response format, the1776

participants’ task is to identify the correct answer from five choices. The average of the subjective
Chinese Mandarin word and sentence recognition scores across all six participants are obtained foreach testing condition. Each participant participated in Chinese Mandarin word and sentence
recognition test of a total of 14 conditions which included 7 different RTs (including a test condition
with no reverberation and six reverberation conditions) and 2 SNRs conditions. During the test, theparticipant adjusted the sound pressure level to his/her favorite level. Because the test recording error,
the Chinese word test score was deleted in room 4 under 5 dBA SNR.

3. RESULTS AND DISCUSSION
The subjective Chinese word and sentence recognition in all rooms is conducted with the different
SNRs. Figures 1 show the Chinese word and sentence recognition scores and their standard deviatio ns
in different rooms and different SNRs, respectively. It can be seen from the Figure 1 that, both Chinese
word and sentence recognition scores for elderly in these rooms increased with the increase of SNRs
and decreased with the increase of RTs.
10080g6040
Word, 5dBA
Word, -5dBA
Sentence, 5dBA
Sentence, -5dBA

2001234567Room No.

Chinese word and sentence recognition scores /%Figure 1 –Chinese word and sentence recognition scores and their standard deviations
The Chinese word and sentence recognition scores of elderly are plotted against the corresponding
STI from different test conditions in Figures 2. The correlation coefficients R and standard deviations(SDs) are 0.85, 6.5%; 0.94, 10.8%. To compare the difference in scores from different age group, therelationship between STI and Chinese word and sentence recognition scores of adults is also plotted inFigures 2. The data came from Peng (13) and Peng (14), respectively. Figures 2 show that both Chinese
word and sentence recognition scores increase as the STI and the age increases.
100908070
60
50
40
Word, elderly
Sentence, elderly
Word, Young adults
Sentence, Young adults

3020
10
0
0.1

0.2

0.3

0.4

0.5

0.6

0.7

STIFigure 2 -Relationship between Chinese word and sentence recognition scores and STI
Both RT and SNR impact critical communication for the elderly. In this study, speech -shape noise
which has the similar spectrum with speech test signals is mixed. The speech -shape noise can mask theChinese word and sentence by energetic masking and decrease the recognition score of word and1777

sentence. Moreover, reverberation sounds also interfered with the word recognition by smeared thetime gap between syllables. The longer the RT is, the lower the word and sentence recognition scoresare. And more, the reverberation also interferes with the recognition of subsequent words and reduces
the word and sentence recognition scores (15). When the reverberation and noise combines, especiallythe long RT, the reverberation not only strongly smear the word, but also enhance the noise level that
increases the masking effect of noise on the word. All these factors result in the word and sentence
recognition scores for the elderly in these rooms decreased with the increase of RTs and increased with
the increase of SNRs.
Sentence recognition requires the listener to extract both word and semantic information from thetest speech signal, as well as acoustical information. There are two basic operations involved in therecognition of words with in sentences (16). One is the initial processing of acoustic-phonetic
information, the other is the utilization of linguistic-situational information of speech (16, 17). The
word recognition in a sentence is constrained by phonetic input and context. Listeners can utilize
different sources of knowledge about the structure of spoken language, including phonological,
prosodic, lexical, semantic, syntactic, and situational, to constrain word choice. When STI is morethan 0.42, the elderly can associate many Chinese words in the whole sentence according to several
key Chinese words, and the score of sentence recognition is higher than that of word recognition.
When STI is less than 0.42, the Chinese test words that can hear clearly are limited and the elde rly
cannot associate the whole sentence, so the score of sentence recognition is lower than that of word
recognition. On the other hand, the elderly's hearing and speech perception reduced gradually (18, 19),Figure 2 demonstrates that the word recognition scores and sentence recognition scores are lower thanthose of young adults. Figure 3 shows the relationship between the word recognition score andsentence recognition score of the elderly. There is high correlation between the word recognition scoreand sentence recognition score of the elderly and the correlation coefficient R is 0.86. When the word
recognition score is lower than 80%, the sentence recognition score is lower than the word recognition
score. When the word recognition score is higher than 80%, the sentence recognition score is higher
than the word recognition score.
Sentence recognition scores /%1008060

40

2005060708090Word recognition scores /%100Figure 3 -Relationship between the word recognition scores and sentence recognition scores of theelderly4. CONCLUSIONSIn the present work, six rooms were modelled by ODEON and the simulated binaural room impulse
responses with different RT were obtained. The binaural room impulse responses were convolved withthe test word and sentence signals, and noise signal and reproduced by headphone. The subjective
word and sentence recognition scores for elderly under different SNR and RT were obtained. The
results show that the shorter the RT, the higher the scores of word recognition and sentence recognition
for the elderly. The higher the SNR, the higher the scores of word recognition and sentence recognition.
There is high correlation between the scores of word recognition and sente nce recognition for theelderly.

ACKNOWLEDGEMENTS
The authors thank the elderly who participated in this work. This work is supported by National
Natural Science Foundation of China (Grant No. 11674104).

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