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Abstract
Transposition of high-frequency information to lower frequencies may help people with high-frequency hearing loss associated with a ‘dead region’ (DR) to detect and identify certain consonants, such as ‘s’. Conventional high-frequency amplification is often not beneficial in such cases. We designed and evaluated a new transposition algorithm which was adapted to each subject's high-frequency DR. Frequency components from well within the DR were transposed to just within the DR without applying frequency compression. Low-frequency components were amplified, but unaffected by transposition. Transposition only occurred if there was significant high-frequency energy, preventing high-frequency background noise of moderate level from being transposed. Consonant discrimination was tested using vowel-consonant-vowel (VCV) stimuli, and the detection of word-final ‘s’ and ‘z’ was assessed using word pairs. Seven subjects with high-frequency DRs were tested in quiet using a transposed and a control condition. Following transposition, two subjects improved significantly and none performed significantly worse on the VCV-test overall. The perception of affricates was consistently improved. Averaged across subjects, the detection of word-final ‘s’ and ‘z’ was significantly improved, with five subjects improving significantly individually.
| Acronyms | ||
| DR | = | Dead region |
| ERBN | = | The average value of the equivalent rectangular bandwidth of the auditory filter at moderate sound levels for young listeners with no known hearing loss |
| fe | = | Edge frequency of dead region |
| FFT | = | Fast Fourier transform |
| IT | = | Information transmitted |
| PTC | = | Psychophysical tuning curve |
| RAU | = | Rationalized arcsine units |
| SL | = | Sensation level |
| TEN | = | Threshold equalizing noise |
| VCV | = | Vowel-consonant-vowel |
| Acronyms | ||
| DR | = | Dead region |
| ERBN | = | The average value of the equivalent rectangular bandwidth of the auditory filter at moderate sound levels for young listeners with no known hearing loss |
| fe | = | Edge frequency of dead region |
| FFT | = | Fast Fourier transform |
| IT | = | Information transmitted |
| PTC | = | Psychophysical tuning curve |
| RAU | = | Rationalized arcsine units |
| SL | = | Sensation level |
| TEN | = | Threshold equalizing noise |
| VCV | = | Vowel-consonant-vowel |
Sumario
La transposición de frecuencias agudas a frecuencias menores puede ayudar a las personas con hipoacusia en frecuencias agudas asociada a una “zona muerta” (DR) para detectar e identificar ciertas consonantes como /s/. La amplificación convencional para frecuencias agudas a menudo no es benéfica en tales casos. Diseñamos y evaluamos un nuevo algoritmo de transposición que fue adaptado a la DR de las frecuencias agudas de cada sujeto. Se transpusieron los componentes frecuenciales dentro de la DR justo alrededor de la DR sin aplicar la compresión frecuencial. Se amplificaron los componentes de baja frecuencia que no se afectaron por la transposición. Sólo se efectuó la transposición cuando había energía de frecuencias agudas significativa, previniendo así la transposición del ruido de fondo de alta frecuencia de nivel moderado. Se probó la discriminación consonántica utilizando estímulos compuestos por vocal-consonante-vocal (VCV) y la detección de /s/ final se evaluó utilizando pares de palabras. Se evaluaron 7 sujetos con DR en frecuencias agudas en condición de transposición y control. Después de la transposición dos sujetos mejoraron significativamente y ninguno empeoró en la prueba VCV. La percepción de las fricativas mejoró consistentemente. En el promedio transversal de los sujetos, la detección de la /s/ y la /z/ finales, mejoró significativamente, y cinco sujetos mejoraron significativamente en forma individual.