Wilson Richard H
Phoenix VA Health Care System, Phoenix, AZ, and Arizona State University, Tempe, AZ.
J Am Acad Audiol. 2015 Apr;26(4):346-54. doi: 10.3766/jaaa.26.4.3.
In 1940, a cooperative effort by the radio networks and Bell Telephone produced the volume unit (vu) meter that has been the mainstay instrument for monitoring the level of speech signals in commercial broadcasting and research laboratories. With the use of computers, today the amplitude of signals can be quantified easily using the root mean square (rms) algorithm. Researchers had previously reported that amplitude estimates of sentences and running speech were 4.8 dB higher when measured with a vu meter than when calculated with rms. This study addresses the vu-rms relation as applied to the carrier phrase and target word paradigm used to assess word-recognition abilities, the premise being that by definition the word-recognition paradigm is a special and different case from that described previously.
The purpose was to evaluate the vu and rms amplitude relations for the carrier phrases and target words commonly used to assess word-recognition abilities. In addition, the relations with the target words between rms level and recognition performance were examined.
Descriptive and correlational.
Two recoded versions of the Northwestern University Auditory Test No. 6 were evaluated, the Auditec of St. Louis (Auditec) male speaker and the Department of Veterans Affairs (VA) female speaker.
Using both visual and auditory cues from a waveform editor, the temporal onsets and offsets were defined for each carrier phrase and each target word. The rms amplitudes for those segments then were computed and expressed in decibels with reference to the maximum digitization range. The data were maintained for each of the four Northwestern University Auditory Test No. 6 word lists. Descriptive analyses were used with linear regressions used to evaluate the reliability of the measurement technique and the relation between the rms levels of the target words and recognition performances.
Although there was a 1.3 dB difference between the calibration tones, the mean levels of the carrier phrases for the two recordings were -14.8 dB (Auditec) and -14.1 dB (VA) with standard deviations <1 dB. For the target words, the mean amplitudes were -19.9 dB (Auditec) and -18.3 dB (VA) with standard deviations ranging from 1.3 to 2.4 dB. The mean durations for the carrier phrases of both recordings were 593-594 msec, with the mean durations of the target words a little different, 509 msec (Auditec) and 528 msec (VA). Random relations were observed between the recognition performances and rms levels of the target words. Amplitude and temporal data for the individual words are provided.
The rms levels of the carrier phrases closely approximated (±1 dB) the rms levels of the calibration tones, both of which were set to 0 vu (dB). The rms levels of the target words were 5-6 dB below the levels of the carrier phrases and were substantially more variable than the levels of the carrier phrases. The relation between the rms levels of the target words and recognition performances on the words was random.
1940年，广播网络和贝尔电话公司合作研发出了音量单位（vu）表，它一直是商业广播和研究实验室中监测语音信号电平的主要仪器。如今，随着计算机的应用，信号幅度可以通过均方根（rms）算法轻松量化。研究人员此前曾报告称，用vu表测量句子和连续语音的幅度估计值比用rms计算时高4.8分贝。本研究探讨了vu与rms的关系，该关系适用于用于评估单词识别能力的载体短语和目标词范式，前提是根据定义，单词识别范式是一个与先前描述的情况不同的特殊案例。
旨在评估常用于评估单词识别能力的载体短语和目标词的vu与rms幅度关系。此外，还研究了rms电平与目标词之间的识别性能关系。
描述性和相关性研究。
对西北大学听觉测试第6号的两个重新录制版本进行了评估，即圣路易斯听觉公司（Auditec）的男性说话者版本和退伍军人事务部（VA）的女性说话者版本。
利用波形编辑器中的视觉和听觉线索，为每个载体短语和每个目标词定义了时间起始点和终止点。然后计算这些片段的rms幅度，并以相对于最大数字化范围的分贝表示。为西北大学听觉测试第6号的四个单词列表中的每一个都保留了数据。使用描述性分析和线性回归来评估测量技术的可靠性以及目标词的rms电平与识别性能之间的关系。
尽管校准音之间存在1.3分贝的差异，但两个录音中载体短语的平均电平分别为-14.8分贝（Auditec）和-14.1分贝（VA），标准差<1分贝。对于目标词，平均幅度分别为-19.9分贝（Auditec）和-18.3分贝（VA），标准差范围为1.3至2.4分贝。两个录音中载体短语的平均持续时间均为593 - 594毫秒，但目标词的平均持续时间略有不同，分别为509毫秒（Auditec）和528毫秒（VA）。在目标词的识别性能和rms电平之间观察到随机关系。提供了各个单词的幅度和时间数据。
载体短语的rms电平与校准音的rms电平紧密接近（±1分贝），两者均设置为0 vu（分贝）。目标词的rms电平比载体短语的电平低5 - 6分贝，并且比载体短语的电平变化大得多。目标词的rms电平与单词识别性能之间的关系是随机的。
