The Experts below are selected from a list of 12 Experts worldwide ranked by ideXlab platform

Lionel Collet - One of the best experts on this subject based on the ideXlab platform.

  • enhanced frequency discrimination near the hearing loss cut off a consequence of central auditory plasticity induced by cochlear damage
    Brain, 2003
    Co-Authors: Hung Thaivan, Brian C J Moore, Christophe Micheyl, Lionel Collet
    Abstract:

    Patients with steeply sloping hearing losses of cochlear origin may exhibit enhanced difference limens for frequency (DLFs) near the cut-off frequency (Fc) of their hearing loss. This effect has been related to observations in deafened animals of an over-representation of Fc in the primary auditory cortex. However, alternative interpretations in terms of peripheral mechanisms have not been eliminated. In the present study, we assessed the possible role of two peripheral mechanisms [loudness cues and spontaneous otoacoustic emissions (SOAEs)] in a group of patients with high-frequency hearing loss. We tested first whether the DLF enhancement effect was still observed under conditions where subjects could not rely on loudness cues to perform the frequency discrimination task. To achieve this, we adjusted the nominal level of each stimulus so that it fell on an equal loudness Contour measured at very fine (1/8 octave) frequency intervals, and we roved the level of each stimulus over a large range (12 dB). Under these conditions, the DLF enhancement was still observed in all patients; this demonstrates that the effect cannot be explained simply by loudness cues. We then screened the patients for SOAEs to test whether the DLF enhancement effect could be explained by the presence of such emissions in the vicinity of the Fc. None of the patients exhibited SOAEs. Finally, we tested whether the patients had cochlear dead regions, i.e. regions lacking functional inner hair cells and/or auditory nerve fibres. Using a refined version of a non-invasive clinical test for the identification of dead regions, we assessed the presence of such regions in fine frequency steps (1/4 octave) up to very high frequencies. All of the patients had cochlear dead regions. The first two findings support the hypothesis that DLF enhancement is due to injury-induced central reorganization in the auditory system. The last one is consistent with neurophysiological data in animals, which suggest that complete deprivation from auditory input at certain cochlear sites may be a necessary condition for the occurrence of injury-induced cortical reorganization.

  • local improvement in auditory frequency discrimination is associated with hearing loss slope in subjects with cochlear damage
    Brain, 2002
    Co-Authors: Hung Thaivan, Christophe Micheyl, Arnaud Norena, Lionel Collet
    Abstract:

    Earlier data in the literature have shown local improvements in frequency discrimination performance near the cut‐off frequency of steeply sloping, high‐frequency hearing loss in subjects with cochlear damage. The general objective of the present study was to characterize further the relationships between this effect and various audiometric variables: namely, the slope, extent and shape of the hearing loss. In particular, we were interested in determining whether the effect was present in subjects with more moderately sloping hearing loss and/or other patterns of loss. Frequency difference limens (DLFs) were measured in 20 subjects (eight female, 12 male, median age 55.5 years) with high‐frequency hearing loss. At least 12 frequencies were tested at intervals of 1/8 octave over a range of 1.5 octaves around the cut‐off frequency for hearing loss (Fc). The Fc corresponded to the audiogram edge frequency and was defined as the highest test frequency, at the beginning of the slope, with a hearing threshold of no more than 5 dB HL above that of the best hearing frequency. The level of the test tones was randomized over a range of 6 dB around a nominal level, following an equal‐loudness Contour curve measured at 1/2‐octave intervals. Results showed that DLFs were significantly smaller in a frequency band 1/4 octave wide centred on Fc than in the other bands. Furthermore, the average DLF measured in this band proved to be negatively correlated with the slope of hearing loss. No such significant relationship was found with the other audiometric indices considered, namely, the extent and maximum amount of hearing loss and the log‐transformed cut‐off frequency. The 20 subjects were divided into three groups according to the slope of their hearing loss relative to Fc (steep, >25 dB/1/2 octave; medium, between 12 and 25 dB/1/2 octave; and shallow, <12 dB/1/2 octave). A local improvement in DLF around Fc was observed in the steep‐ and medium‐slope groups and was confirmed statistically in the steep‐slope group. Similar measurements in subjects with low‐frequency or notched hearing loss allowed us to establish the presence of similar local improvements in DLFs around audiogram edges. These results, which suggest the slope of the hearing loss to be the most important factor for the occurrence of local DLF improvements, are consistent with both an interpretation in terms of peripheral mechanisms and one in terms of central mechanisms, i.e. injury‐induced neural reorganization.

Hung Thaivan - One of the best experts on this subject based on the ideXlab platform.

  • enhanced frequency discrimination near the hearing loss cut off a consequence of central auditory plasticity induced by cochlear damage
    Brain, 2003
    Co-Authors: Hung Thaivan, Brian C J Moore, Christophe Micheyl, Lionel Collet
    Abstract:

    Patients with steeply sloping hearing losses of cochlear origin may exhibit enhanced difference limens for frequency (DLFs) near the cut-off frequency (Fc) of their hearing loss. This effect has been related to observations in deafened animals of an over-representation of Fc in the primary auditory cortex. However, alternative interpretations in terms of peripheral mechanisms have not been eliminated. In the present study, we assessed the possible role of two peripheral mechanisms [loudness cues and spontaneous otoacoustic emissions (SOAEs)] in a group of patients with high-frequency hearing loss. We tested first whether the DLF enhancement effect was still observed under conditions where subjects could not rely on loudness cues to perform the frequency discrimination task. To achieve this, we adjusted the nominal level of each stimulus so that it fell on an equal loudness Contour measured at very fine (1/8 octave) frequency intervals, and we roved the level of each stimulus over a large range (12 dB). Under these conditions, the DLF enhancement was still observed in all patients; this demonstrates that the effect cannot be explained simply by loudness cues. We then screened the patients for SOAEs to test whether the DLF enhancement effect could be explained by the presence of such emissions in the vicinity of the Fc. None of the patients exhibited SOAEs. Finally, we tested whether the patients had cochlear dead regions, i.e. regions lacking functional inner hair cells and/or auditory nerve fibres. Using a refined version of a non-invasive clinical test for the identification of dead regions, we assessed the presence of such regions in fine frequency steps (1/4 octave) up to very high frequencies. All of the patients had cochlear dead regions. The first two findings support the hypothesis that DLF enhancement is due to injury-induced central reorganization in the auditory system. The last one is consistent with neurophysiological data in animals, which suggest that complete deprivation from auditory input at certain cochlear sites may be a necessary condition for the occurrence of injury-induced cortical reorganization.

  • local improvement in auditory frequency discrimination is associated with hearing loss slope in subjects with cochlear damage
    Brain, 2002
    Co-Authors: Hung Thaivan, Christophe Micheyl, Arnaud Norena, Lionel Collet
    Abstract:

    Earlier data in the literature have shown local improvements in frequency discrimination performance near the cut‐off frequency of steeply sloping, high‐frequency hearing loss in subjects with cochlear damage. The general objective of the present study was to characterize further the relationships between this effect and various audiometric variables: namely, the slope, extent and shape of the hearing loss. In particular, we were interested in determining whether the effect was present in subjects with more moderately sloping hearing loss and/or other patterns of loss. Frequency difference limens (DLFs) were measured in 20 subjects (eight female, 12 male, median age 55.5 years) with high‐frequency hearing loss. At least 12 frequencies were tested at intervals of 1/8 octave over a range of 1.5 octaves around the cut‐off frequency for hearing loss (Fc). The Fc corresponded to the audiogram edge frequency and was defined as the highest test frequency, at the beginning of the slope, with a hearing threshold of no more than 5 dB HL above that of the best hearing frequency. The level of the test tones was randomized over a range of 6 dB around a nominal level, following an equal‐loudness Contour curve measured at 1/2‐octave intervals. Results showed that DLFs were significantly smaller in a frequency band 1/4 octave wide centred on Fc than in the other bands. Furthermore, the average DLF measured in this band proved to be negatively correlated with the slope of hearing loss. No such significant relationship was found with the other audiometric indices considered, namely, the extent and maximum amount of hearing loss and the log‐transformed cut‐off frequency. The 20 subjects were divided into three groups according to the slope of their hearing loss relative to Fc (steep, >25 dB/1/2 octave; medium, between 12 and 25 dB/1/2 octave; and shallow, <12 dB/1/2 octave). A local improvement in DLF around Fc was observed in the steep‐ and medium‐slope groups and was confirmed statistically in the steep‐slope group. Similar measurements in subjects with low‐frequency or notched hearing loss allowed us to establish the presence of similar local improvements in DLFs around audiogram edges. These results, which suggest the slope of the hearing loss to be the most important factor for the occurrence of local DLF improvements, are consistent with both an interpretation in terms of peripheral mechanisms and one in terms of central mechanisms, i.e. injury‐induced neural reorganization.

Christophe Micheyl - One of the best experts on this subject based on the ideXlab platform.

  • enhanced frequency discrimination near the hearing loss cut off a consequence of central auditory plasticity induced by cochlear damage
    Brain, 2003
    Co-Authors: Hung Thaivan, Brian C J Moore, Christophe Micheyl, Lionel Collet
    Abstract:

    Patients with steeply sloping hearing losses of cochlear origin may exhibit enhanced difference limens for frequency (DLFs) near the cut-off frequency (Fc) of their hearing loss. This effect has been related to observations in deafened animals of an over-representation of Fc in the primary auditory cortex. However, alternative interpretations in terms of peripheral mechanisms have not been eliminated. In the present study, we assessed the possible role of two peripheral mechanisms [loudness cues and spontaneous otoacoustic emissions (SOAEs)] in a group of patients with high-frequency hearing loss. We tested first whether the DLF enhancement effect was still observed under conditions where subjects could not rely on loudness cues to perform the frequency discrimination task. To achieve this, we adjusted the nominal level of each stimulus so that it fell on an equal loudness Contour measured at very fine (1/8 octave) frequency intervals, and we roved the level of each stimulus over a large range (12 dB). Under these conditions, the DLF enhancement was still observed in all patients; this demonstrates that the effect cannot be explained simply by loudness cues. We then screened the patients for SOAEs to test whether the DLF enhancement effect could be explained by the presence of such emissions in the vicinity of the Fc. None of the patients exhibited SOAEs. Finally, we tested whether the patients had cochlear dead regions, i.e. regions lacking functional inner hair cells and/or auditory nerve fibres. Using a refined version of a non-invasive clinical test for the identification of dead regions, we assessed the presence of such regions in fine frequency steps (1/4 octave) up to very high frequencies. All of the patients had cochlear dead regions. The first two findings support the hypothesis that DLF enhancement is due to injury-induced central reorganization in the auditory system. The last one is consistent with neurophysiological data in animals, which suggest that complete deprivation from auditory input at certain cochlear sites may be a necessary condition for the occurrence of injury-induced cortical reorganization.

  • local improvement in auditory frequency discrimination is associated with hearing loss slope in subjects with cochlear damage
    Brain, 2002
    Co-Authors: Hung Thaivan, Christophe Micheyl, Arnaud Norena, Lionel Collet
    Abstract:

    Earlier data in the literature have shown local improvements in frequency discrimination performance near the cut‐off frequency of steeply sloping, high‐frequency hearing loss in subjects with cochlear damage. The general objective of the present study was to characterize further the relationships between this effect and various audiometric variables: namely, the slope, extent and shape of the hearing loss. In particular, we were interested in determining whether the effect was present in subjects with more moderately sloping hearing loss and/or other patterns of loss. Frequency difference limens (DLFs) were measured in 20 subjects (eight female, 12 male, median age 55.5 years) with high‐frequency hearing loss. At least 12 frequencies were tested at intervals of 1/8 octave over a range of 1.5 octaves around the cut‐off frequency for hearing loss (Fc). The Fc corresponded to the audiogram edge frequency and was defined as the highest test frequency, at the beginning of the slope, with a hearing threshold of no more than 5 dB HL above that of the best hearing frequency. The level of the test tones was randomized over a range of 6 dB around a nominal level, following an equal‐loudness Contour curve measured at 1/2‐octave intervals. Results showed that DLFs were significantly smaller in a frequency band 1/4 octave wide centred on Fc than in the other bands. Furthermore, the average DLF measured in this band proved to be negatively correlated with the slope of hearing loss. No such significant relationship was found with the other audiometric indices considered, namely, the extent and maximum amount of hearing loss and the log‐transformed cut‐off frequency. The 20 subjects were divided into three groups according to the slope of their hearing loss relative to Fc (steep, >25 dB/1/2 octave; medium, between 12 and 25 dB/1/2 octave; and shallow, <12 dB/1/2 octave). A local improvement in DLF around Fc was observed in the steep‐ and medium‐slope groups and was confirmed statistically in the steep‐slope group. Similar measurements in subjects with low‐frequency or notched hearing loss allowed us to establish the presence of similar local improvements in DLFs around audiogram edges. These results, which suggest the slope of the hearing loss to be the most important factor for the occurrence of local DLF improvements, are consistent with both an interpretation in terms of peripheral mechanisms and one in terms of central mechanisms, i.e. injury‐induced neural reorganization.

Brian C J Moore - One of the best experts on this subject based on the ideXlab platform.

  • dead regions in the cochlea and enhancement of frequency discrimination effects of audiogram slope unilateral versus bilateral loss and hearing aid use
    Hearing Research, 2006
    Co-Authors: Karolina Kluk, Brian C J Moore
    Abstract:

    Following a restricted lesion of the cochlea, which produces a "dead region" (DR), animal experiments have revealed an increase in the cortical representation of frequencies just below the edge frequency (f(e)) of the DR. This may result in improved difference limens for frequency (DLFs) just below f(e). In previous studies to assess this, the value of f(e) was not determined precisely. We measured DLFs using human subjects with DRs for whom the values of f(e) had been determined precisely using psychophysical tuning curves. To prevent use of loudness cues, stimuli for the measurement of DLFs had a mean level falling along an Equal-Loudness Contour and levels were roved over a 12-dB range. DLFs were measured for thirteen subjects with a DR in at least one ear. Almost all subjects with bilateral hearing loss exhibited enhanced DLFs near f(e), consistent with cortical reorganisation. This occurred for subjects whose audiograms had both steep and shallow slopes, regardless of hearing aid use, and for two subjects with low-frequency DRs. One subject with a high-frequency DR in one ear and good hearing in the other ear showed an enhanced DLF in her better ear.

  • enhanced frequency discrimination near the hearing loss cut off a consequence of central auditory plasticity induced by cochlear damage
    Brain, 2003
    Co-Authors: Hung Thaivan, Brian C J Moore, Christophe Micheyl, Lionel Collet
    Abstract:

    Patients with steeply sloping hearing losses of cochlear origin may exhibit enhanced difference limens for frequency (DLFs) near the cut-off frequency (Fc) of their hearing loss. This effect has been related to observations in deafened animals of an over-representation of Fc in the primary auditory cortex. However, alternative interpretations in terms of peripheral mechanisms have not been eliminated. In the present study, we assessed the possible role of two peripheral mechanisms [loudness cues and spontaneous otoacoustic emissions (SOAEs)] in a group of patients with high-frequency hearing loss. We tested first whether the DLF enhancement effect was still observed under conditions where subjects could not rely on loudness cues to perform the frequency discrimination task. To achieve this, we adjusted the nominal level of each stimulus so that it fell on an equal loudness Contour measured at very fine (1/8 octave) frequency intervals, and we roved the level of each stimulus over a large range (12 dB). Under these conditions, the DLF enhancement was still observed in all patients; this demonstrates that the effect cannot be explained simply by loudness cues. We then screened the patients for SOAEs to test whether the DLF enhancement effect could be explained by the presence of such emissions in the vicinity of the Fc. None of the patients exhibited SOAEs. Finally, we tested whether the patients had cochlear dead regions, i.e. regions lacking functional inner hair cells and/or auditory nerve fibres. Using a refined version of a non-invasive clinical test for the identification of dead regions, we assessed the presence of such regions in fine frequency steps (1/4 octave) up to very high frequencies. All of the patients had cochlear dead regions. The first two findings support the hypothesis that DLF enhancement is due to injury-induced central reorganization in the auditory system. The last one is consistent with neurophysiological data in animals, which suggest that complete deprivation from auditory input at certain cochlear sites may be a necessary condition for the occurrence of injury-induced cortical reorganization.

Arnaud Norena - One of the best experts on this subject based on the ideXlab platform.

  • local improvement in auditory frequency discrimination is associated with hearing loss slope in subjects with cochlear damage
    Brain, 2002
    Co-Authors: Hung Thaivan, Christophe Micheyl, Arnaud Norena, Lionel Collet
    Abstract:

    Earlier data in the literature have shown local improvements in frequency discrimination performance near the cut‐off frequency of steeply sloping, high‐frequency hearing loss in subjects with cochlear damage. The general objective of the present study was to characterize further the relationships between this effect and various audiometric variables: namely, the slope, extent and shape of the hearing loss. In particular, we were interested in determining whether the effect was present in subjects with more moderately sloping hearing loss and/or other patterns of loss. Frequency difference limens (DLFs) were measured in 20 subjects (eight female, 12 male, median age 55.5 years) with high‐frequency hearing loss. At least 12 frequencies were tested at intervals of 1/8 octave over a range of 1.5 octaves around the cut‐off frequency for hearing loss (Fc). The Fc corresponded to the audiogram edge frequency and was defined as the highest test frequency, at the beginning of the slope, with a hearing threshold of no more than 5 dB HL above that of the best hearing frequency. The level of the test tones was randomized over a range of 6 dB around a nominal level, following an equal‐loudness Contour curve measured at 1/2‐octave intervals. Results showed that DLFs were significantly smaller in a frequency band 1/4 octave wide centred on Fc than in the other bands. Furthermore, the average DLF measured in this band proved to be negatively correlated with the slope of hearing loss. No such significant relationship was found with the other audiometric indices considered, namely, the extent and maximum amount of hearing loss and the log‐transformed cut‐off frequency. The 20 subjects were divided into three groups according to the slope of their hearing loss relative to Fc (steep, >25 dB/1/2 octave; medium, between 12 and 25 dB/1/2 octave; and shallow, <12 dB/1/2 octave). A local improvement in DLF around Fc was observed in the steep‐ and medium‐slope groups and was confirmed statistically in the steep‐slope group. Similar measurements in subjects with low‐frequency or notched hearing loss allowed us to establish the presence of similar local improvements in DLFs around audiogram edges. These results, which suggest the slope of the hearing loss to be the most important factor for the occurrence of local DLF improvements, are consistent with both an interpretation in terms of peripheral mechanisms and one in terms of central mechanisms, i.e. injury‐induced neural reorganization.