Masking of English Words by Prolonged Vowel Sounds

One‐hundred and ten monosyllabic words selected from the Thorndike list of 1000 most frequently occurring words in English to represent equally each of 10 vowels were presented to 300 American listeners in an articulation test. Also tested were 72 spondee words, half selected from those in use in audiological tests and half from those in frequent use in air traffic control, further to represent the same vowel sounds. Masking of the stimuli was accomplished by recording separately each of nine prolonged vowels intoned by a trio of male voices. Results indicate that vowels of equal sound pressure levels differ considerably in masking effectiveness, that words containing specific vowel are not masked optimally by the same vowel, and that spondees are masked by prolonged vowels in the same rank as are the monosyllables. Prolonged vowel sounds with relatively high concentrations of energy between 700 and 1000 cps are most effective as masking agents. Rank order correlation of observed masking effectiveness with masking effectiveness predicted by the Strasberg method is 0.52, the Beranek method is 0.59, and by the Pickett‐Kryter method, 0.69. Some observations on resistance of words to masking are made in relation to phonemic transition areas within words.