Comparison of Tonotopic and Default Frequency Fitting for Speech Understanding in Noise in New Cochlear Implantees: A Prospective, Randomized, Double-Blind, Cross-Over Study

Creff, Gwenaelle; Lambert, Cassandre; Coudert, Paul; Pean, Vincent; Laurent, Stephane; Godey, Benoit

doi:10.1097/aud.0000000000001423

Cited by 3 publications

(5 citation statements)

References 115 publications

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“…Coincidentally, Creff et al, 2024 showed speech understanding benefit when using non-standard vs conventional frequency maps aimed at reducing frequency mismatch that appear to closely match the level-corrected tonotopic reference of the present study (i.e., BF70). Tonotopic fitting was achieved via postoperative flat-panel CT for each subject by measuring the cochlear duct length from the round window to a given electrode and then using Greenwood’s (1990) human coefficients to determine the associated frequency.…”

Section: Discussionsupporting

confidence: 67%

“…Coincidentally, Creff et al, 2024 showed speech understanding benefit when using nonstandard vs conventional frequency maps aimed at reducing frequency mismatch that appear to closely match the level-corrected tonotopic reference of the present study (i.e., BF70).…”

Section: Implications For Cochlear Implantssupporting

confidence: 67%

“…Whether this change will amount to perceived benefit over standard-of-care settings is unclear. Although several studies have demonstrated varying degrees of benefit when using anatomical-based fitting (Di Maro et al, 2022; Dillon et al, 2023; Fan et al, 2023; Kurtz et al, 2023; Tóth et al, 2023; Creff et al, 2024; Dessard et al, 2024), others have demonstrated either no benefit or poorer performance in comparison to standard-of-care (Grasmeder et al, 2014; Jiam et al, 2018; Dirks et al, 2022; Lambriks et al, 2023). Part of the problem is in how the anatomical-based place-frequency map is defined.…”

Section: Discussionmentioning

confidence: 99%

“…Assigning Greenwood frequencies to the upper edge of an electrode’s passband resulted in its center frequencies becoming shifted down by about 3 semitones, which is near the average level-corrected shift described in the present study. Although indirect, Creff et al (2024) offers support for achieving speech understanding benefit when using a non-standard frequency allocation that reduces frequency mismatch, but that is less extreme than place-frequency maps derived more strictly from Greenwood’s (1990) human coefficients (and associated spiral ganglion corrections). The present study provides justification for why such an intermediary map may be, in fact, a more accurate tonotopic reference.…”

Section: Discussionmentioning

confidence: 99%

“…Although indirect, Creff et al (2024) offers support for achieving speech understanding benefit when using a non-standard frequency allocation that reduces frequency mismatch, but that is less extreme than place-frequency maps derived more strictly from Greenwood's (1990) human coefficients (and associated spiral ganglion corrections). The present study provides justification for why such an intermediary map may be, in fact, a more accurate tonotopic reference.…”

Section: Implications For Cochlear Implantsmentioning

confidence: 99%

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A level adjusted cochlear frequency-to-place map for estimating tonotopic frequency mismatch with a cochlear implant

Sagi,

Svirsky

2024

Preprint

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ObjectivesTo provide a level-adjusted correction to the current standard relating anatomical cochlear place to characteristic frequency in humans, and to re-evaluate anatomical frequency mismatch in cochlear implant (CI) recipients considering this correction. It is hypothesized that a level-adjusted place-frequency function may represent a more accurate tonotopic benchmark for CIs in comparison to the current standard.DesignThe present analytical study compiled data from fifteen previous animal studies that reported iso-intensity responses from cochlear structures at different stimulation levels. Extracted outcome measures were characteristic frequencies and centroid-based best frequencies at 70 dB SPL input from 47 specimens spanning a broad range of cochlear locations. A simple relationship was used to transform these measures to human estimates of characteristic and best frequencies, and non-linear regression was applied to these estimates to determine how the standard human place-frequency function should be adjusted to reflect best frequency rather than characteristic frequency. The proposed level-adjusted correction was then compared to average place-frequency positions of commonly used CI devices when programmed with clinical settings.ResultsThe present study showed that the best frequency at 70 dB SPL (BF70) tends to shift away from characteristic frequency (CF). The amount of shift was statistically significant (signed-rank test z = 5.143, p < 0.001), but the amount and direction of shift depended on cochlear location. At cochlear locations up to 600° from the base, BF70 shifted downwards in frequency relative to CF by about 4 semitones on average. Beyond 600° from the base, BF70 shifted upwards in frequency relative to CF by about 6 semitones on average. In terms of spread (90% prediction interval), the amount of shift between CF and BF70 varied from relatively no shift to nearly an octave of shift. With the new level-adjusted frequency-place function, the amount of anatomical frequency mismatch for devices programmed with standard of care settings is less extreme than originally thought, and may be nonexistent for all but the most apical electrodes.ConclusionsThe present study validates the current standard for relating cochlear place to characteristic frequency, and introduces a level-adjusted correction for how best frequency shifts away from characteristic frequency at moderately loud stimulation levels. This correction may represent a more accurate tonotopic reference for CIs. To the extent that it does, its implementation may potentially enhance perceptual accommodation and speech understanding in CI users, thereby improving CI outcomes and contributing to advancements in the programming and clinical management of CIs.

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Section: Discussionsupporting

confidence: 67%

Section: Implications For Cochlear Implantssupporting

confidence: 67%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Implications For Cochlear Implantsmentioning

confidence: 99%

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A level adjusted cochlear frequency-to-place map for estimating tonotopic frequency mismatch with a cochlear implant

Sagi,

Svirsky

2024

Preprint

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Tonotopic and Default Frequency Fitting for Music Perception in Cochlear Implant Recipients

Creff,

Bernard-Le Liboux,

Coudert

et al. 2024

JAMA Otolaryngol Head Neck Surg

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ImportanceCochlear implants are an effective technique for enhancing speech perception abilities in quiet environments for people with severe to profound deafness. Nevertheless, complex sound signals perception, such as music perception, remains challenging for cochlear implant users.ObjectiveTo assess the benefit of a tonotopic map on music perception in new cochlear implant users.Design, Setting, and ParticipantsA prospective, randomized, double-blind, 2-period crossover study including 26 new cochlear implant users was performed over a 6-month period (June 2021 to November 2021). An anatomical tonotopic map was created using postoperative flat-panel computed tomography and a reconstruction software based on Greenwood function. New cochlear implant users older than 18 years with bilateral severe to profound sensorineural hearing loss or complete hearing loss for less than 5 years were selected in the University Hospital Centre of Rennes in France. The trial was conducted from June to November 2021 (inclusion) and to February 2022 (end of the assessment procedure at 12 weeks postactivation), and the analysis itself was completed in December 2022.InterventionEach participant was randomized to receive a conventional map followed by a tonotopic map or vice versa.Main Outcomes and MeasuresParticipants performed pitch-scaling tasks (multidimensional qualitative assessment, melodic contour identification, melodic recognition test) after 6 weeks of each setting.ResultsThirteen participants were randomized to each sequence. Two of the 26 participants recruited (1 in each sequence) had to be excluded due to the COVID-19 pandemic. The multidimensional qualitative assessment (Gabrielsson test), melodic contour identification, and melodic recognition scores were significantly higher with the tonotopic setting than the conventional one (mean effect [ME], 7.8; 95% CI, 5.0-10.5; ME, 12.1%; 95% CI, 5.7%-18.4%; ME, 14.4%, 95% CI, 8.5%-20.2%; and ME, 2.1, 95% CI, 1.7-2.5, respectively). Among the different dimensions evaluated by the Gabrielsson test, the mean scores for clarity, spaciousness, fullness, nearness, and total impression were significantly higher with tonotopic fitting. Ninety-two percent of the participants kept the tonotopy-based map after the study period.ConclusionsIn this randomized clinical trial of patients with new cochlear implants, a tonotopic-based fitting was associated with better results in perception of complex sound signals such as music listening experience.Trial RegistrationClinicalTrials.gov Identifier: NCT04922619

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Electrocochleography-Based Tonotopic Map: II. Frequency-to-Place Mismatch Impacts Speech-Perception Outcomes in Cochlear Implant Recipients

Walia,

Shew,

Varghese

et al. 2024

Ear &Amp; Hearing

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Objectives: Modern cochlear implants (CIs) use varying-length electrode arrays inserted at varying insertion angles within variably sized cochleae. Thus, there exists an opportunity to enhance CI performance, particularly in postlinguistic adults, by optimizing the frequency-to-place allocation for electrical stimulation, thereby minimizing the need for central adaptation and plasticity. There has been interest in applying Greenwood or Stakhovskaya et al. function (describing the tonotopic map) to postoperative imaging of electrodes to improve frequency allocation and place coding. Acoustically-evoked electrocochleography (ECochG) allows for electrophysiologic best-frequency (BF) determination of CI electrodes and the potential for creating a personalized frequency allocation function. The objective of this study was to investigate the correlation between early speech-perception performance and frequency-to-place mismatch. Design: This retrospective study included 50 patients who received a slim perimodiolar electrode array. Following electrode insertion, five acoustic pure-tone stimuli ranging from 0.25 to 2 kHz were presented, and electrophysiological measurements were collected across all 22 electrode contacts. Cochlear microphonic tuning curves were subsequently generated for each stimulus frequency to ascertain the BF electrode or the location corresponding to the maximum response amplitude. Subsequently, we calculated the difference between the stimulus frequency and the patient’s CI map’s actual frequency allocation at each BF electrode, reflecting the frequency-to-place mismatch. BF electrocochleography-total response (BF-ECochG-TR), a measure of cochlear health, was also evaluated for each subject to control for the known impact of this measure on performance. Results: Our findings showed a moderate correlation (r = 0.51; 95% confidence interval: 0.23 to 0.76) between the cumulative frequency-to-place mismatch, as determined using the ECochG-derived BF map (utilizing 500, 1000, and 2000 Hz), and 3-month performance on consonant-nucleus-consonant words (N = 38). Larger positive mismatches, shifted basal from the BF map, led to enhanced speech perception. Incorporating BF-ECochG-TR, total mismatch, and their interaction in a multivariate model explained 62% of the variance in consonant-nucleus-consonant word scores at 3 months. BF-ECochG-TR as a standalone predictor tended to overestimate performance for subjects with larger negative total mismatches and underestimated the performance for those with larger positive total mismatches. Neither cochlear diameter, number of cochlear turns, nor apical insertion angle accounted for the variability in total mismatch. Conclusions: Comparison of ECochG-BF derived tonotopic electrode maps to the frequency allocation tables reveals substantial mismatch, explaining 26.0% of the variability in CI performance in quiet. Closer examination of the mismatch shows that basally shifted maps at high frequencies demonstrate superior performance at 3 months compared with those with apically shifted maps (toward Greenwood and Stakhovskaya et al.). The implications of these results suggest that electrophysiological-based frequency reallocation might lead to enhanced speech-perception performance, especially when compared with conventional manufacturer maps or anatomic-based mapping strategies. Future research, exploring the prospective use of ECochG-based mapping techniques for frequency allocation is underway.

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Comparison of Tonotopic and Default Frequency Fitting for Speech Understanding in Noise in New Cochlear Implantees: A Prospective, Randomized, Double-Blind, Cross-Over Study

Cited by 3 publications

References 115 publications

A level adjusted cochlear frequency-to-place map for estimating tonotopic frequency mismatch with a cochlear implant

A level adjusted cochlear frequency-to-place map for estimating tonotopic frequency mismatch with a cochlear implant

Tonotopic and Default Frequency Fitting for Music Perception in Cochlear Implant Recipients

Electrocochleography-Based Tonotopic Map: II. Frequency-to-Place Mismatch Impacts Speech-Perception Outcomes in Cochlear Implant Recipients

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