Masking Level Differences for Tones and Speech in Elderly Listeners With Relatively Normal Audiograms

Abstract

This study measured the masking level difference (MLD) for both 500-Hz tone detection and spondee word recognition in two groups of listeners. One group consisted of 9 elderly listeners with normal audiometric sensitivity bilaterally, up to at least 2000 Hz. The other group was a control group of 10 young listeners with normal hearing. The intent was to determine whether the elderly listeners exhibited a reduction in binaural performance that might contribute to the difficulties many such listeners have in understanding speech in noisy situations. By measuring MLDs in elderly listeners in the absence of marked peripheral hearing loss, it was hoped that any observed changes in MLD could be more strongly attributed to central effects. For both tone detection and speech recognition, it was found that the elderly performed more poorly than the young listeners, primarily on the NoSπ condition.

Masking-level differences in older adults: The effect of the level of the masking noise

“…In prior studies comparing older listeners with clinically significant degrees of presbycusis to younger listeners with normal audiograms, small but significant effects of group on the size of the MLD were found (Jerger, Brown, & Smith, 1984;Novak & Anderson, 1982;Olsen, Noffsinger, & Carhart, 1976;Stubblefield & Goldstein, 1977; but see Kelly-Ballweber & Dobie, 1984, whose younger and older subjects were matched for hearing loss). However, the size of the group effect on MLDs observed here and in the experiment of Grose et al (1994) is somewhat larger than what has been previously reported in other studies of older listeners with relatively good audiometric thresholds (Jerger et al, 1984;Novak & Anderson, 1982). A possible explanation for this apparent discrepancy is that the subjects who participated in our experiments were actually in the early stages of presbycusis, with pure-tone thresholds that did not meet strict criteria for normal hearing at the high frequencies.…”

“…The MLDs of older listeners with good hearing were significantly (up to 5 dB) smaller in all conditions. Similar differences were found by Grose, Poth, and Peters (1994) and PichoraFuller and Schneider (1992), It is possible that the smaller MLDs ofolder adults were observed because the level of the masker was not suffi- ciently intense for them to have achieved maximum performance. Numerous studies have shown that the size of the MLD increases as the level of the masker increases until a plateau is reached where the size ofthe MLD is constant with further increases in masker level (Blodgett, Jeffress, & Whitworth, 1962;Canahl & Small, 1965;Diercks & Jeffress, 1962;Dolan, 1968;Dolan & Robinson, 1967;Hall & Harvey, 1984, 1985Hall, Tyler, & Fernandes, 1983;Henning & Zwicker, 1984;Hirsh, 1948;McFadden, 1968;Yost, 1988).…”

“…Consequently, we might expect the age effect observed by other investigators to be smaller than the one observed in the present experiments because other investigators used continuously presented masking noise. However, like us (Pichora-Fuller & Schneider, 1991), Grose et al (1994) found a significant age effect on MLD using a continuous masker, so the failure to find significant age effects cannot be due solely to whether the masker is presented continuously or in a burst.…”

Binaural hearing ability with mastoid applied bilateral bone conduction stimulation in normal hearing subjects

“…Here, the phase-inversion of the speech signal gave a benefit of 7.6 dB, while for the same condition using a material of everyday sentences, George et al (2012) reported an improvement of 5.5 dB. In another study where spondaic words were used as targets, an improvement of 8.8 dB was found in young normal-hearing subjects when the phase of the speech was inverted (Grose et al, 1994). Once again, the difference in speech material could explain the slight difference between that study and the results here.…”

Effects of Age and Hearing Loss on the Processing of Auditory Temporal Fine Structure

“…Because the BMLD represents a difference between two thresholds, it has the advantage that differences in processing efficiency across age groups at least partly cancel. Several researchers have compared BMLDs for young and older subjects with (near-) normal hearing Schneider 1991, 1992;Grose et al 1994;Strouse et al 1998). All showed that BMLDs (usually for a 500-Hz signal frequency) were smaller for older than for young subjects, typically by 2-4 dB.…”