Janet E. Shanks

Speech recognition performance of patients with sensorineural hearing loss under unaided and aided conditions using linear and compression hearing AIDS.

Objectives This study compared speech recognition performance on the Northwestern University Auditory Test No. 6 (NU-6) and the Connected Speech Test (CST) for three hearing aid circuits (peak clipping [PC], compression limiting [CL], and wide dynamic range compression [WDRC]) in adults with symmetrical sensorineural hearing loss. The study also questioned whether or not hearing aid benefit for the three circuits was dependent upon the speech level and the signal-to-babble ratio (S/B) and upon the degree and slope of hearing loss. Design Unaided speech recognition performance for NU-6 and CST materials presented from a loudspeaker at 0° was measured during Visit 1, and both unaided and aided performance was measured at 3-mo intervals during Visits 2 to 4. The NU-6 was presented in quiet at a conversational speech level of 62 dB SPL. The CST was presented in 10 listening conditions—three S/B (−3, 0, and 3 dB) at each of three speech levels (soft speech at 52 dB SPL, conversational speech at 62 dB SPL, and loud speech at 74 dB SPL) and in quiet at 74 dB SPL. Uncorrelated multi-talker babble was presented from two loudspeakers at 45° on each side of the main speaker. Hearing aid benefit was examined for 360 subjects divided into four groups of hearing loss, pure tone average <40 dB HL and slope <10 dB/octave or >10 dB/octave and hearing loss >40 dB HL for the two slope categories. Results Hearing aid benefit (aided minus unaided performance) measured on the NU-6 in quiet exceeded 31 rau for all three circuits. Although small statistical advantages were found for the WDRC, the differences were ∼2% and are not considered clinically relevant. Unaided CST performance showed a complex relationship between presentation level and signal-to-babble ratio that was further confounded by the degree of hearing loss. For the two mild hearing loss groups and for each of the three nominal signal-to-babble ratios, CST performance decreased by 20 rau for the −3 dB S/B to 6 rau for the 3 dB S/B as speech level increased from 52 to 74 dB SPL. In contrast, unaided performance increased by 32 to 13 rau with signal level for all signal-to-babble ratios for the two >40 dB hearing loss groups. Overall, aided CST performance exceeded unaided performance for all 10 conditions. As expected, hearing aid benefit was greatest (27 rau) for soft speech and smallest for loud speech (6 rau). Differences among the hearing aid circuits were small with only one significant difference; the WDRC at 62/0 was poorer by 3 rau than the other two circuits. When the CST data were analyzed as a function of hearing loss, five pair-wise comparisons were significant. In contrast to the unaided performance, aided performance for all hearing loss groups decreased as presentation level increased, even though the signal-to-babble ratio was constant. Conclusions All three hearing aids circuits provided benefit over the unaided condition in both quiet and noise. The greatest benefit was measured for soft speech in the more severe hearing loss groups. Although only small differences were measured among the three hearing aid circuits, significant differences favored the PC and CL circuits over the WDRC in the mild hearing loss groups and favored the WDRC over the PC in the more severe, sloping hearing loss group. An interesting interaction between speech level, signal-to-babble ratio, degree of hearing loss, and amplification was found. For a constant signal-to-babble ratio, recognition performance decreased as speech level increased from 52 to 74 dB SPL. The effect was most marked in the milder hearing loss groups and in the aided conditions, and occurred at even the lowest speech levels.

A multi-center, double blind clinical trial comparing benefit from three commonly used hearing aid circuits.

Objective Although numerous studies have demonstrated that hearing aids provide significant benefit, carefully controlled, multi-center clinical trials have not been conducted. A multi-center clinical trial was conducted to compare the efficacy of three commonly used hearing aid circuits: peak clipping, compression limiting, and wide dynamic range compression. Design Patients (N = 360) with bilateral, sensorineural hearing loss were studied using a double blind, three-period, three-treatment crossover design. The patients were fit with each of three programmable hearing aid circuits. Outcome tests were administered in the unaided condition at baseline and then after 3 mo usage of each circuit, the tests were administered in both aided and unaided conditions. The outcome test battery included tests of speech recognition, sound quality and subjective scales of hearing aid benefit, including patients’ overall rank-order rating of the three circuits. Results Each hearing aid circuit improved speech recognition markedly, with greater improvement observed for soft and conversationally loud speech in both quiet and noisy listening conditions. In addition, a significant reduction in the problems encountered in communication was observed. Some tests suggested that the two compression hearing aids provided a better listening experience than the peak clipping hearing aid. In the rank-order ratings, patients preferred the compression limiting hearing aid more frequently than the other two hearing aids. Conclusions The three hearing aid circuits studied provide significant benefit both in quiet and in noisy listening situations. The two compression hearing aids appear to provide superior benefits compared to the linear circuit, although the differences between the hearing aids were smaller than the differences between unaided and aided conditions.

Spondaic word detection and recognition functions for female and male speakers.

The Department of Veterans Affairs recently produced a compact disc of speech audiometry materials. The compact disc, which is available commercially, includes the W-1 spondaic words recorded by a female speaker. Two experiments were conducted. The purposes of experiment 1 were to obtain normative detection and recognition data on the female recording of the spondaic words and to compare the detection and recognition functions for the original male speaker version of the W-1 words. No significant differences were found between the recognition functions for each speaker. The recognition functions for both speakers were displaced to higher sound-pressure levels by 8 dB above the detection functions. Clinically, the two versions of the W-1 spondaic words should produce equivalent results. In experiment 2, slopes of the individual spondaic word recognition functions for the female speaker were obtained from two listeners and are discussed in terms of interstimulus, intertrial, and intersubject variability.

10 – Acoustic-Reflex Adaptation

Acoustic-reflex adaptation was studied in 35 subjects with normal hearing using nine pure-tone activators (250-6000 Hz) and a broadband-noise activator. The individual subject data generated by the...

Measurement of Acoustic Transients During Pulsed Holmium:YAG Laser Ablation of Cadaveric Human Temporal Bone

Abstract.Pulsed infrared (IR) and ultraviolet (UV) lasers have been suggested for use in middle ear surgery due to potential fiberoptic delivery, decreased thermal trauma and precise ablation characteristics. Although attention has been focused on the thermal and photoacoustic events that occur during pulsed laser ablation of hard tissue, there are few studies which evaluate the acoustic energy generated from these devices from an audiological standpoint. In this study, the mastoid cavities of cadaveric human temporal bones were irradiated with a holmium: yttrium aluminium garnet (Ho:YAG) laser (λ=2.12 µm) using the following parameters: 5, 10, and 15 Hz pulse repetition rate and 1, 2, 4, 6, 8, and 10 W average power. During ablation, acoustic measurements were made using a sound level meter positioned 5 cm away from the target site. With each set of laser parameters, the sound intensity exceeded 85 dB (dBA scale). Peak intensities of 125 dB were measured, and a saturation effect noted above 4 W or 500 mJ/pulse. The clinical significance of these findings is discussed and the acoustical aspects of middle ear function and noise trauma are reviewed.

Acoustic measurements during holmium:YAG laser ablation of cadaveric human temporal bone: preliminary observations

Pulsed IR and UV lasers have been suggested for use in middle ear surgery due to decreased thermal trauma, precise ablation characteristics, and potential fiberoptic delivery. While there has been much focus on the thermal and photoacoustic events that occur during pulsed laser ablation of hard tissue, there are few studies that look at the acoustic energy generated from these devices from an audiologic standpoint. In this study, the mastoid cavities of cadaveric human temporal bones were irradiated with a Ho:YAG laser (lambda equals 2.12 micrometer) with the following parameters: 5, 10, and 15 Hz pulse repetition rate and 1, 2, 4, 6, 8, and 10 W average power. During ablation, acoustic measurements were made using a sound level meter held 5 cm away from the target site. With each set of laser parameters, the sound intensity (dB SPL) exceeded 85 dB. Peak intensity measurements of 125 dB were measured, and a saturation effect was noted above 4 W or 500 mJ/pulse. The clinical significance of these findings is discussed and the acoustical aspects of middle ear function and noise trauma are reviewed.