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Researching Speech Recognition


Summary table of sound enhancement efficacy studies demonstrating improvement in speech-recognition skills

Table data taken directly from Sound Field Amplification: Applications to Speech Perception and Classroom Acoustics (Second Edition) by Carl C. Crandell, Joseph J. Smaldino, and Carol Flexer.

Investigators Student Population Improvement in Speech Recognition
Obtained with SES*'s
Crandell & Bess (1986) 20 students with normal hearing Students showed significant improvement in sentence recognition ability under the amplified condition in typical classroom (S/N = +6 DB, RT=0.6 sec).
Blair, Myrup & Viehweg (1989) 10 students (CA=7-14 yrs) with mild to moderate SNHL Students with mild to moderate SNHL demonstrated an average of 12% improvement in word-recognition score when using personal hearing aids with FM sound field over hearing aids alone.
Jones, Berg, & Viehweg (1989) Kindergarten students with normal hearing (N=18) and mild hearing loss (N=18) Use of FM sound field amplification decreased student-teacher distance and produced word-recognition scores comparable to close listening at 4 feet.
Flexer, Millin, & Brown (1990) Primary school-age children with developmental disabilities Developmentally disabled students with history of persistent conductive hearing loss exhibited improved word-recognition scores.
Crandell (1993) 20 students with normal hearing Significantly higher word-recognition scores were achieved by students at distances of 12 and 24 feet when using a SES*
Zabel & Tabor (1993) 145 regular education 3rd through 5th grade students Students achieved improved spelling test scores under FM sound field amplification in quiet and under degraded listening at a +12 dB SNR.
Crandell (1996) 20 nonnative English speaking children Improved speech-perception scores were achieved at distances of 12 and 24 feet when using a SES*
Allcock (1999) Three amplified and two unamplified elementary classrooms in New Zealand After 8 weeks of sound field amplification use, students in amplified classrooms showed a 65-74% improvement of 1 stanine on the Test of Phonological Awareness compared to students in unamplified classes showing a 46% improvement of 1 stanine.
Gordon-Langbein & Metinger (1999) 2 elementary classrooms Students' abilities to identify initial consonant phonemes in words, using recorded questions, improved by 45% in the amplified conditions.
Eriks-Brophy & Ayukawa (2000) 20 second and third-grade students (10 with hearing loss and 10 age-matched peers) Significant improvements in speech intelligibility were noted for recognition of Inuttitut syllables by both groups of students when using a SES*.
Lederman, Johnson, Crandell, & Smaldino (2000) 72 third grade students (ELL, at risk, special education) and 9 third through fifth grade hard of hearing students Significant improvement on 16 of 40 listening tasks (words and CV syllables) and conditions (S/N at -6, 0,+6dB) using the SmartSpeaker "Intelligence" digital signal processing sound field system with ambient noise compensation (ANC) capability.
Prendergast (2001) 31 third-grade and 33 fourth-grade students with normal hearing Enhanced performance was shown by all children on the California Consonant Test using the bending wave speaker vs. a traditional sound field speaker.
Mendel, Roberts, & Walton (2003) 128 regular education kindergarten students with normal hearing 2 year study showed significant and immediate improvement in speech perception and accelerated development of speech perception in noise by students in amplified classrooms.
Updike & Conner (2003) 495 first-grade students in regular education classes Significant improvement in Goldman-Fristoe Test of Auditory Discrimination scores in quiet (76% to 92%) and noise (60% to 84%)


* SES = Sound Enhancement System