A frequency importance function for continuous discourse

Abstract

Normal hearing subjects estimated the intelligibility of continuous discourse (CD) passages spoken by three talkers (two male and one female) under 135 conditions of filtering and signal-to-noise ratio. The relationship between the intelligibility of CD and the articulation index (the transfer function) was different from any found in ANSI S3.5-1969. Also, the lower frequencies were found to be relatively more important for the intelligibility of CD than for identification of nonsense syllables and other types of speech for which data are available except for synthetic sentences [Speaks, J. Speech Hear. Res. 10, 289-298 (1967)]. The frequency which divides the auditory spectrum into two equally important halves (the crossover frequency) was found to be about 0.5 oct lower for the CD used in this study than the crossover frequency for male talkers of nonsense syllables found in ANSI S3.5-1969 and about 0.7 oct lower than the one for combined male and female talkers of nonsense syllables reported by French and Steinberg [J. Acoust. Soc. Am. 19, 90-119 (1947)].

Spectral fissioning in phonemic transformations

“…The use of bandpass filtering demonstrated that different spectral ranges were employed for each of the forms: one form usually corresponded to a band of frequencies below 1500 Hz and the other to a band of frequencies above 1500 Hz. Interestingly, there is considerable evidence that a frequency of approximately 1500 ± 300 Hz (depending on stimuli and procedures) divides speech into highpass and low-pass ranges of equal intelligibility (Beranek, 1947;Fletcher & Galt, 1950;Hirsh, Reynolds, & Joseph, 1954;Pollack & Pickett, 1964;Studebaker, Pavlovic, & Sherbecoe, 1987). Sentences provide higher intelligibility scores than do word lists, and each of two nonoverlapping spectral ranges can be quite intelligible when heard alone.…”

A Speech Intelligibility Index-based approach to predict the speech reception threshold for sentences in fluctuating noise for normal-hearing listeners

“…In order to be able to predict the speech intelligibility under such masking conditions, French and Steinberg ͑1947͒, Fletcher and Galt ͑1950͒, and later Kryter ͑1962a, b͒ initiated a calculation scheme, known as the Articulation Index ͑AI͒, which at present still is used by a number of investigators ͑Rankovic, 1998investigators ͑Rankovic, , 2002Hogan and Turner, 1998;Müsch and Buus, 2001;Turner and Henry, 2002;Dubno et al, 2002, 2003͒. In 1984, Pavlovic and others ͑Dirks et al, 1986Kamm et al, 1985;Pavlovic and Studebaker, 1984;Pavlovic et al, 1986;Studebaker et al, 1987 started to re-examine the AI calculation scheme, which has led to a new method accepted as the ANSI S3.5-1997 ͑1997͒. Since its revision in 1997, the method is named the Speech Intelligibility Index ͑SII͒.…”

Spectral redundancy: Intelligibility of sentences heard through narrow spectral slits

“…frequencies, it was necessary to add masking noise to further degrade these signals so that intelligibility would vary with cutoff changes (see Studebaker, Pavlovic, & Sherbecoe, 1987). Pavlovic (1994) summarized some of this recent work and listed 1/3-octave band importance functions for a variety of speech materials, including sentences, short passages, and average speech.…”