A comparison between the electrically reproduced loudness and the original loudness of speech at high levels

Four words lists of a German Speech Intelligibility Test (DIN 45621) were recorded at 60 and 75 dB SPL. Both recordings were presented to 20 normally hearing subjects at 75 dB SPL via free-field equalized earphones. Discrimination in noise was significantly better in the original recording at 60 dB SPL. The better understanding may be explained by a more favourable consonant-vowel intensity ratio. Moreover, a significant increase in fundamental frequency could be demonstrated at the higher recording level. The implications for speech audiometry and hearing aids are discussed. Furthermore, it was found from loudness comparisons that both recordings were equally loud at a level of 75 dB SPL. However, significantly increased loudness was indicated in the 75 dB SPL recording by the loudness calculation procedure ISO 532 B.