The effects of consonant-vowel intensity ratios on speech loudness in monosyllables

Previous research on normal-hearing and hearing-impaired listeners at a high presentation level (90 dB SPL) suggested that information about speech loudness is contained primarily in the vowel in consonant-vowel-consonant (CVC) monosyllables, and that consonant intensity has a negligible effect. The purpose of the present study was to further examine the unique aspects of speech loudness by manipulating consonant-vowel intensity ratios (CVRs), while holding the vowel constant, at a comfortable listening level (70 dB) to determine whether vowels and consonants contribute differentially to the loudness of monosyllabic words with voiced and voiceless consonants. Words edited to have CVRs ranging from -6 to +6 dB were presented to 10 normal-hearing listeners and compared to a standard word with unaltered CVR in an adaptive procedure to obtain the loudness in relative dB. Loudness and overall level as a function of CVR were compared for four word types: CVC words with both voiceless consonants modified; words with only the initial voiceless consonants modified; CVC words with both voiced consonants modified; and words with only the initial voiced consonants modified. Results indicate that the loudness of CVC monosyllables is not based on strict vowel dominance; rather, the overall level of the word and the level of the vowel contribute approximately equally. Possible implications for the design of cochlear implants are presented.