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Abstract
Real-ear measurements using the modified pressure method with concurrent (real-time) equalization can be inaccurate, when amplified sound leaks out of the ear canal and reaches the reference microphone. In such situations the reference microphone will detect an increased sound level and reduce the output of the loudspeaker to maintain the desired level. The risk of having errors due to leaks increases if digital feedback suppression (DFS) is used, thus achieving higher feedback-free gain levels. The following hypotheses were tested: a) using the concurrent equalization method for fitting hearing instruments with DFS may result in underestimated real-ear insertion gain (especially when using open fittings) and b) as the benefit of the DFS system increases, this error also increases. Real-ear measurements were carried out in twenty-one subjects using the modified pressure method with stored equalization as well as with concurrent equalization. The results of the study supports both hypotheses. As a consequence it is recommended to use a stored equalization method for real-ear measurements of hearing instruments with DFS and open fitting.
| Acronyms | ||
| BTE | = | Behind-the-ear |
| dB | = | Decibel |
| DFS | = | Digital feedback suppression |
| Hz | = | Hertz |
| MPCE | = | Modified pressure method with concurrent equalization |
| MPSE | = | Modified pressure method with stored equalization |
| MSG | = | Maximum stable gain |
| REAR | = | Real-ear aided response |
| REIG | = | Real-ear insertion gain |
| REM | = | Real-ear measurements |
| REUR | = | Real-ear unaided response |
| SD | = | Standard deviation |
| Acronyms | ||
| BTE | = | Behind-the-ear |
| dB | = | Decibel |
| DFS | = | Digital feedback suppression |
| Hz | = | Hertz |
| MPCE | = | Modified pressure method with concurrent equalization |
| MPSE | = | Modified pressure method with stored equalization |
| MSG | = | Maximum stable gain |
| REAR | = | Real-ear aided response |
| REIG | = | Real-ear insertion gain |
| REM | = | Real-ear measurements |
| REUR | = | Real-ear unaided response |
| SD | = | Standard deviation |
Sumario
Las mediciones en oído real que utilizan el método de presión modificada con ecualización concurrente (en tiempo real), pueden ser imprecisas cuando el sonido amplificado se escapa fuera del conducto auditivo y alcanza el micrófono de referencia. En tales situaciones el micrófono de referencia detectará un aumento en el nivel de sonido y reducirá la salida de la bocina para mantener el nivel deseado. El riesgo de tener errores debidos a fugas aumenta si se utiliza supresión por retroalimentación digital (DFS), y se alcanzará un mayor nivel de ganancia libre de retroalimentación. Se probaron las siguientes hipótesis: a) al utilizar el método de ecualización concurrente para la adaptación de instrumentos auditivos con DFS puede provocar una ganancia de oído real subestimada (especialmente cuando se usan moldes abiertos) y b) conforme aumenta el beneficio del DFS, este error también se incrementa. Se llevaron a cabo mediciones de oído real en 21 sujetos utilizando el método de presión modificada con ecualización acumulada, así como con ecualización concurrente. El resultado del estudio apoya ambas hipótesis. Como consecuencia se recomienda utilizar el método de ecualización acumulada para mediciones de instrumentos auditivos en oído real con DFS y moldes abiertos.
