"Speech as well as environmental sounds are important for communication in everyday life. When the spectral and temporal information of these sounds is distorted or restricted, numerous studies have found that older listeners show a larger decline in recognition performance compared to the young. The present study compares recognition performances of young and elderly listeners with normal hearing (YNH and ENH groups) when low-pass spectral filtering and time compression were applied to monosyllables or environmental sounds. All the words and sounds were presented at 65 dB SPL, and the subjects wrote down the monosyllables they heard or made answers to the list of the environmental sounds. When the monosyllabic words were low-pass filtered with 6, 4, 3, 2 and 1 kHz cutoff frequencies with or without time comprssion of 40%, the effects of aging, spectral filtering, and time compression were all significant. When the environmental sounds were presented in the closed-set format under the same conditions, all the factors of aging, spectral filtering, and time compression significantly affected listeners' performances as well. This result suggests that, regardless of whether the words or environmental sounds are spectrally or temporally distorted, a greater spectral and temporal distortion results in worse recognition performance. Our data supports the previous finding that the old listeners have a declined ability to recognize monosyllabic words and environmental sounds which are spectrally or temporally distorted. The most common type of word recognition errors was initial consonant replacement for both YNH and ENH groups. Especially, the high-frequency (>4kHz) initial consonants among the wrong answers were frequently replaced with other consonants with lower-frequency information. Results of error analyses revealed that the most common error type for word recognition was initial consonant replacement in both YNH and ENH groups. Especially, initial consonants with high-frequency information (>4 kHz) were frequently replaced with other consonants with lower frequency information. KEY WORDS : Aging, Environmental sound recognition, Monosyllabic word recognition, Spectral filtering, Time compression."