A graphical method for calculating the speech intelligibility index and measuring hearing disability from audiograms

Abstract

The speech intelligibility index (SII) is interpreted as the proportion of total speech information available to the listener's ear for a given speech material. Consequently, SII varies in the range 0-1. A simple graphical method for determining SII for monaural listening at 1 m distance from a talker producing "average speech" (or PB-words) at normal speech effort is described. The speech area is visualized by 10 x 10 = 100 points in the audiogram form, each point contributing 0.01 to the SII. The SII thus equals 0.01 times the number of points in the audible range. A sensorineural hearing loss gives rise to an additional loss in speech recognition due to reduced frequency discrimination and time resolving ability. This suprathreshold deficit is corrected for, if the SII contribution in each frequency band is multiplied with a hearing threshold level dependent "desensitization factor". The SII is related to the intelligibility of speech, and may be used to evaluate a hearing disability.

Does Language Matter When Using a Graphical Method for Calculating the Speech Intelligibility Index?

“…In addition, we compared the predicted SII values for the three languages using the same audiogram for the unaided and aided conditions. The method used to create graphical SIIs was similar to methods used by Kringlebotn (1999) and Killion and Mueller (2010). Kringlebotn (1999) created a graphical SII using ten band divisions with 30 dB DR.…”

“…The method used to create graphical SIIs was similar to methods used by Kringlebotn (1999) and Killion and Mueller (2010). Kringlebotn (1999) created a graphical SII using ten band divisions with 30 dB DR. The overall speech level was 62.35 dB SPL, corresponding to normal speech effort.…”

“…The SII calculation is a complicated procedure (ANSI, 1997/R2012); therefore, several researchers have suggested simplified graphical methods for clinical use (e.g., Mueller and Killion, 1990;Pavlovic, 1991;Kringlebotn, 1999;Killion and Mueller, 2010). One such graphical method is the count-the-dot audiogram (Mueller and Killion, 1990;Killion and Mueller, 2010).…”

Methods and Applications of the Audibility Index in Hearing Aid Selection and Fitting

“…It should be noted that measured speech scores would differ somewhat from the predicted scores based on the Al, depending on the actual speech stimulus used and the proficiency of the talker and listener. D. Simplified Methods of Calculating Al There have been several attempts at simplifying the calculation of the Al for clinical use (Pavlovic, 1988(Pavlovic, , 1991Mueller and Killion, 1990;Humes, 1991;Kringlebotn, 1999). All of these schemes make use of an audiogram display, so that the hearing thresholds can be plotted directly onto the audiogram for calculating the AI.…”

“…[R1997] specifications, where 1 octave on the X-axis should equal 20 dB on the Y-axis.) Kringlebotn (1999) recently derived a graphical method based on the newer standard for calculating the Al from audiometric data. In its simplest form, this model assumes monaural listening at a distance of 1 meter from a talker who is expending normal vocal effort.…”