Comparison of vu-meter-based and rms-based calibration of speech levels

Abstract

A difference of approximately 5dB exists between the level of spoken English determined using the ANSI standard vu-meter method compared to the common root-mean-square (rms) method. If the rms method is substituted for the present ANSI standard method for calibrating a speech audiometer, for example, the reported speech reception thresholds will improve 5dB: Speech levels read approximately 5dB less using rms. Similarly, the reported signal-to-noise ratio required to understand speech in a speech-spectrum noise will be 5dB better using rms. A simple method for obtaining a close approximation to traditional calibrations using a modified rms method is given.

Amplitude (vu and rms) and Temporal (msec) Measures of Two Northwestern University Auditory Test No. 6 Recordings

“…T he rms levels of the carrier phrases commonly used with word-recognition materials closely approximate the rms levels of calibration tones when both are set to the same vu level. This relation supports the contention that the 4.8 dB relation between the rms and vu levels observed with running speech and sentence materials by Killion (2009) is not observed with the carrier phrase and target word paradigm commonly used clinically to measure word-recognition performance. The carrier phrases used with wordrecognition testing have modest amplitude modulation characteristics compared to the amplitude modulation characteristics of the two types of materials evaluated by Killion.…”

“…Lobdell and Allen (2007, p. 281) suggested that "Reading a VU meter is more of an art than a science". Killion (2009) reviewed the technique that can be used to read a vu meter that we were taught years ago by Tom Tillman. This technique requires multiple visualizations of the reading (of the vu needle) with the first attempt(s) used to narrow the visual range on the meter Figure 1.…”

“…Several years ago, Killion (2009) compared the calibration of speech levels using vu meter and rms measures of speech signals and calibration tones. In the course of two experiments, running speech (Ludvigsen, 1992) and the Institute of Electrical and Electronics Engineers sentences incorporated in the QuickSIN test (Killion et al, 2004) were used to compare the vu and rms levels of each material.…”

Audiometric Calibration: Speech Signals

“…These advances rendered the VU meter obsolete with its complicated analog circuitry. 17 There is now a diversity of speech test materials available, each designed for a specific application and to provide specific information that can be used in the assessment of an individual's hearing ability. The design of speech tests is not only the subject of continuous research but also continuous criticism.…”

Telecoil-Mode Hearing Aid Compatibility Performance Requirements for Wireless and Cordless Handsets: Magnetic Signal Levels

“…The average speech level was determined according to Method B of International Telecommunications Union (ITU)-T P.56 (1993). Informal measurements have shown this method to result in speech level measurements about 4 to 5 dB lower than those obtained from a traditional approach of observing the level of frequent peaks on a volume units (VU) meter (Killion, 2009). The voice recording employed during the testing for both acoustic and magnetic playback was the same as employed by Nabelek et al (1991;Nabelek et al, 2004).…”