Good speech intelligibility is the primary goal of acoustic environment control in lecture rooms and auditoria. The speech transmission index (STI) is the primary objective evaluation metric for speech intelligibility. Therefore, accurate prediction of the STI during the design stage is important for acoustic environment control in lecture rooms and auditoria. Two types of STI prediction methods based on simulated impulse responses and statistical are recommended by the IEC standard. In this study, the prediction accuracy and influencing factors of these two types of prediction methods were systematically analysed using STI measurements collected at 25 receiver positions in six rooms. The results reveal the following. (1) When the influence of the signal-to-noise ratio (SNR) is not considered, for the STI prediction method based on simulated impulse responses, the prediction accuracy is in an acceptable range with the average predicted STI discrepancy of the 25 receiver positions being −0.004 and the maximum discrepancy being 0.046. For the STI prediction method based on statistical, the average predicted STI discrepancy of the 25 receiver positions was −0.015, and the maximum discrepancy was −0.091. STI prediction based on statistical exhibited a larger prediction error at the receiver positions close to the sound source and smaller prediction error at the receiver positions farther away from the sound source. (2) When the influence of the SNR was considered, the errors of both prediction methods increased significantly. For the STI prediction method based on simulated impulse responses, the average predicted STI discrepancy of the 25 receiver positions was −0.035 and the maximum discrepancy was −0.088. For the STI prediction method based on statistical, the average predicted STI discrepancy of the 25 receiver positions was −0.030 and the maximum discrepancy was −0.112. (3) Using a sound source that is different from the onsite measurement sound source can induce noticeable errors in both methods. (4) For the STI prediction method based on statistical using the actual value of the sound source, the prediction accuracy of receiver positions close to the sound source can be significantly improved and the effect on receiver positions farther away from the sound source is relatively small. (5) Both methods require significant technical expertise from users, rendering it difficult to obtain accurate prediction results during the design stage.

中文翻译：

---

语音传输指数预测方法的实验比较

良好的语音清晰度是报告厅和礼堂声环境控制的首要目标。语音传输指数（STI）是语音清晰度的主要客观评价指标。因此，在设计阶段准确预测STI对于演讲厅和礼堂的声环境控制非常重要。 IEC 标准推荐了两种基于模拟脉冲响应和统计的 STI 预测方法。本研究利用6个房间25个接收器位置采集的STI测量结果，系统分析了这两类预测方法的预测精度和影响因素。结果揭示了以下内容。 (1) 在不考虑信噪比(SNR)的影响时，基于模拟脉冲响应的STI预测方法，预测精度与25个接收机的平均预测STI差异在可接受的范围内位置为-0.004，最大差异为0.046。对于基于统计的STI预测方法，25个接收器位置的平均预测STI差异为-0.015，最大差异为-0.091。基于统计的STI预测在靠近声源的接收器位置处表现出较大的预测误差，而在远离声源的接收器位置处表现出较小的预测误差。 (2)当考虑信噪比的影响时，两种预测方法的误差均显着增加。对于基于模拟脉冲响应的STI预测方法，25个接收器位置的平均预测STI差异为-0.035，最大差异为-0.088。对于基于统计的STI预测方法，25个接收器位置的平均预测STI差异为-0.030，最大差异为-0.112。 (3) 使用与现场测量声源不同的声源可能会导致两种方法产生明显的误差。 (4)基于声源实际值统计的STI预测方法，可以显着提高靠近声源的接收器位置的预测精度，并且对远离声源的接收器位置的影响相对较小。 (5)这两种方法都需要用户具备丰富的技术知识，导致在设计阶段很难获得准确的预测结果。