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Abstract
When the frequency range over which vent-transmitted sound dominates amplification increases, the potential benefit from directional microphones and noise reduction decreases. Fitted with clinically appropriate vent sizes, 23 aided listeners with varying low-frequency hearing thresholds evaluated six schemes comprising three levels of gain at 250 Hz (0, 6, and 12 dB) combined with two features (directional microphone and noise reduction) enabled or disabled in the field. The low-frequency gain was 0 dB for vent-dominated sound, while the higher gains were achieved by amplifier-dominated sounds. A majority of listeners preferred 0-dB gain at 250 Hz and the features enabled. While the amount of low-frequency gain had no significant effect on speech recognition in noise or horizontal localization, speech recognition and front/back discrimination were significantly improved when the features were enabled, even when vent-transmitted sound dominated the low frequencies. The clinical implication is that there is no need to increase low-frequency gain to compensate for vent effects to achieve benefit from directionality and noise reduction over a wider frequency range.
| Acronyms | ||
| AI-DI | = | Articulation index weighted directivity index |
| ANOVA | = | Analysis of variance |
| BKB | = | Bamford-Kowal-Bench sentences |
| BTE | = | Behind-the-ear |
| CD | = | Compact disc |
| DI | = | Directivity index |
| famplified | = | Frequency at which the amplified region begins |
| fvent | = | Frequency at which the vent stops transmitting sounds into the ear |
| HTL | = | Hearing threshold level |
| ITE | = | In-the-ear |
| ITC | = | In-the-canal |
| KEMAR | = | Knowles Electronics Manikin for Acoustic Research |
| MPO | = | Maximum power output |
| OE/i/ | = | Occlusion effect for the vocalized /i/ sound |
| REIG | = | Real-ear insertion gain |
| REOIG | = | Real-ear occluded insertion gain |
| REOIGown | = | Real-ear occluded insertion gain for own voice |
| REUG | = | Real-ear unaided gain |
| RMS | = | Root mean square |
| SPL | = | Sound pressure level |
| SNR | = | Signal-to-noise ratio |
| W | = | Kendall coefficient of concordance |
| WDRC | = | Wide dynamic range compression |
| Acronyms | ||
| AI-DI | = | Articulation index weighted directivity index |
| ANOVA | = | Analysis of variance |
| BKB | = | Bamford-Kowal-Bench sentences |
| BTE | = | Behind-the-ear |
| CD | = | Compact disc |
| DI | = | Directivity index |
| famplified | = | Frequency at which the amplified region begins |
| fvent | = | Frequency at which the vent stops transmitting sounds into the ear |
| HTL | = | Hearing threshold level |
| ITE | = | In-the-ear |
| ITC | = | In-the-canal |
| KEMAR | = | Knowles Electronics Manikin for Acoustic Research |
| MPO | = | Maximum power output |
| OE/i/ | = | Occlusion effect for the vocalized /i/ sound |
| REIG | = | Real-ear insertion gain |
| REOIG | = | Real-ear occluded insertion gain |
| REOIGown | = | Real-ear occluded insertion gain for own voice |
| REUG | = | Real-ear unaided gain |
| RMS | = | Root mean square |
| SPL | = | Sound pressure level |
| SNR | = | Signal-to-noise ratio |
| W | = | Kendall coefficient of concordance |
| WDRC | = | Wide dynamic range compression |
Sumario
Cuando aumenta el rango de frecuencia sobre el que el sonido transmitido a través de la ventilación que domina la amplificación, el beneficio potencial de los micrófonos direccionales y la reducción de ruido disminuye. Veintitrés oyentes con umbrales variables en frecuencias bajas, adaptados con ventilación clínicamente apropiada, evaluaron seis esquemas que comprendían tres niveles de ganancia a 250Hz (0, 6 y 12 dB) combinando la activación de dos condiciones en la situación auditiva (micrófono direccional y reducción de ruido). La ganancia de la frecuencia auditiva fue 0 dB para el sonido dominado por la ventilación, mientras que la mayor ganancia se logró en los sonidos dominados por la amplificación. La mayoría de los oyentes prefirieron la ganancia de 0 dB en 250 Hz y las dos condiciones activadas. Mientras que el monto de ganancia en frecuencias graves no tuvo un efecto significativo en el reconocimiento del lenguaje en ruido o la localización horizontal, el reconocimiento del lenguaje y la discriminación atrás/adelante mejoraron significativamente cuando las condiciones fueron activadas, incluso cuando el sonido transmitido por la ventilación dominaba las frecuencias bajas. La implicación clínica es que no hay necesidad de aumentar la ganancia en las frecuencias bajas para compensar el efecto de la ventilación y lograr así un beneficio en la direccionalidad y la reducción del ruido sobre el rango de frecuencia.