Comparison of Acceptable Noise Level Generated Using Different Transducers and Response Modes

Hindawi Neural Plasticity Volume 2018, Article ID 3786489, 9 pages https://doi.org/10.1155/2018/3786489 Research Article Comparison of Acceptable Noise Level Generated Using Different Transducers and Response Modes Liang Xia,1 Jingchun He,2 Yuanyuan Sun,1 Yi Chen,1 Qiong Luo,1 Haibo Shi ,1 Yanmei Feng ,1 and Shankai Yin 1 1 Department of Otolaryngology, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, No. 600, Yishan Road, Xuhui District, Shanghai 200233, China 2 Department of Otolaryngology, Shanghai Jiao Tong University Affiliated Xinhua Hospital, No. 1665, Kongjiang Road, Yangpu District, Shanghai 200092, China Correspondence should be addressed to Haibo Shi; and Yanmei Feng; Received 5 March 2018; Revised 15 May 2018; Accepted 30 May 2018; Published 26 June 2018 Academic Editor: Geng-lin Li Copyright © 2018 Liang Xia et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The acceptable noise level (ANL) was defined by subtracting the background noise level (BNL) from the most comfortable listening level (MCL) (ANL = MCL − BNL). This study compared the ANL obtained through different methods in 20 Chinese subjects with normal hearing. ANL was tested with Mandarin speech materials using a loudspeaker or earphones, with each subject tested by himself or by the audiologist. The presentation and response modes were as follows: (1) loudspeaker with self-adjusted noise levels using audiometer controls (LS method); (2) loudspeaker with the subject signaling the audiologist to adjust speech and noise levels (LA method); (3) earphones with self-adjusted noise levels using audiometer controls (ES method); and (4) earphones with the subject signaling the audiologist to adjust speech and noise levels (EA method). ANL was calculated from three measurements with each method. There was no significant difference in the ANL obtained through different presentation modes or response modes sound. The correlations between ANL, MCL, and BNL obtained from each two methods were significant. In conclusion, the ANL in normal-hearing Mandarin listeners may not be affected by presentation modes such as a loudspeaker or earphones nor is it affected by self-adjusted or audiologist-adjusted response modes. Earphone audiometry is as reliable as sound field audiometry and provides an easy and convenient way to measure ANL. 1. Introduction The acceptable noise level (ANL) test was developed to quantify the critical amount of background noise that subjects could accept while listening to speech [1–6]. ANL is defined as the lowest signal-to-noise ratio (SNR) that a subject could accept when the target speech was presented at the most comfortable listening level (MCL) [6, 7]. ANL is derived by subtracting the background noise level (BNL) that the subject can accept from the MCL. A low ANL indicates that a subject has a high tolerance for background noises, while a subject with high ANL has low tolerance for background noises [7]. According to Nabelek et al. [8], subjects with an ANL below 7 dB are likely to become successful full-time hearing aid users, while subjects with an ANL above 13 dB are likely to become unsuccessful hearing aids users occasionally or not at all. Previous studies have shown that there is a large variation in ANL across normal-hearing subjects [1, 7, 9–13]. This variation seems unrelated to age [1, 11], gender [14], middle-ear function [15], hearing sensitivity [1, 7, 9, 15, 16], outer hair cell function [15], and efferent pathways utilizing the medial olivocochlear bundle [15]. However, it was influenced by speech materials, noise materials, presentation mode, instructions, and working memory capacity [17]. Several types of sensors have been used to present the ANL signal. In most studies, the sound signal was presented in the sound field through a loudspeaker [18]. However, some studies presented the signals used to measure ANL through an earphone [1]. Olsen and Brännström [17] indicated that the values of ANL obtained from an earphone or loudspeaker may be different. If transducers other than a 2 loudspeaker were used, the ANL data for the specific transducer should be considered. Clinically, audiologists may use ANL data obtained from different transducers. Although most audiologists use a loudspeaker to do ANL, some audiologists could do ANL with earphone when the loudspeaker is not available and predict the ANL results with loudspeaker from the ANL results with earphone. Therefore, it is necessary to contrast different sound presentation modes in ANL tests. On the other hand, Brannstrom et al. [11] suggested that ANL might be influenced by extrinsic factors such as examiner attitude, instructions, and/or cultural differences in the acceptability of background noise. In most ANL tests, the subject signals the experimenter to adjust the sound volume. However, Nabelek et al. [1] directed subjects to adjust the levels by themselves with visual feedback from the audiometer. The main difference between self-adjusted and audiologist-adjusted measurements is the method to determine the MCL and BNL intensity. During the self-adjusted method, the subjects will determine the MCL and BNL by adjusting the sound levels using the control buttons. During the audiologist-adjusted method, the subjects tell the audiologist the optimal intensity and the maximum intensity signal as the noise level changes continuously; however, there could be a time lag or bias of intensity during this period which can produce differences between the final results and the subjects’ true results on ANL tests. To identify factors that may influence ANL values, this study proposed to investigate and compare the test results of ANL measured through a loudspeaker or earphones and further compared the effect of the self-adjusted or audiologist-adjusted testing method. 2. Methods The program was approved by the Ethics Committee of Shanghai Jiao Tong University Affiliated Sixth People’s Hospital. All participants provided written informed consent prior to the study’s commencement. 2.1. Subjects. This study was conducted in twenty adults (10 male, 10 female) with normal hearing whose native language was Mandarin. Their ages ranged from 21 to 30 years and they were all university students. The criterion for normal hearing sensitivity was pure-tone air conduction thresholds for each ear less than or equal to 15 dB HL at each frequency from 0.25 to 8 kHz with an octave step. The subjects reported no recent otologic problems, such as ear infection, draining ears, otalgia, or surgery on or in the ears during the past eight weeks. The equipment set-ups were calibrated before the study started. 2.2. Materials. The test used Mandarin-acceptable noise level material established by Chen et al. [18]. The materials were The Spring Festival of Beijing which was chosen fro (...truncated)