Assessing auditory nerve condition by tone decay in deaf subjects with a cochlear implant

Abstract

The condition of the auditory nerve is a factor determining hearing performance of cochlear implant (CI) recipients. Abnormal loudness adaptation is associated with poor auditory nerve survival. We examined which stimulus conditions are suitable for tone decay measurements to differentiate between CI recipients with respect to their speech perception. Tone decay was defined here as occurring when the percept disappears before the stimulus stops. We measured the duration of the percept of a 60-s pulse train. Current levels ranged from below threshold up to maximum acceptable loudness, pulse rates from 250 to 5000 pulses/s, and duty cycles (percentages of time the burst of pulses is on) from 10% to 100%. Ten adult CI recipients were included: seven with good and three with poor speech perception. Largest differences among the subjects were found at 5000 pulses/s and 100% duty cycle. The well performing subjects had a continuous percept of the 60-s stimulus within 3 dB above threshold. Two poorly performing subjects showed abnormal loudness adaptation, that is, no continuous percept even at levels greater than 6 dB above threshold. We conclude that abnormal loudness adaptation can be detected via an electric tone decay test using a high pulse rate and 100% duty cycle.

Duration of deafness impacts auditory performance after cochlear implantation: A meta‐analysis

“…Twenty‐two studies with 1167 patients presented data on vowel/consonant and monosyllabic word perception scores, namely the best monosyllabic discrimination (BMD) score, 41 the Consonant‐Nucleus‐Consonant (CNC) words, 4,35,38,45‐47 Consonant‐Vowel tests, 31,32,37,48 the Northwestern University Auditory Test No.6 (NU‐6), 29,35,49 Freiburg monosyllabic word test, 34,40 vowel identification score 30,39,50 , a word perception test 15,51,52 and different tests 24 …”

“…The onset of hearing loss was defined by patient history and objective diagnostics. If no correlation coefficient was presented but ample data was available, 23‐35 information on DoD and speech perception would be extracted, while patients with prelingual onset of deafness before the age of 5, 23,25,26,32 data of sequential implantations 28 and duplicate patient data 30,31 were excluded. Data was also obtained from published figures and graphs 25,30,34 …”

Feasibility of a Cochlear Implant Fitting Approach Based on Phoneme Confusions: Lessons Learned from the AuDiET Study

“…In other words, if those suggested interventions are implemented, improving one phoneme confusion error will deteriorate the other, and vice versa. Therefore, for poorer-performing CI-users, the outcomes of other test paradigms may be more informative, including tone-decay, a test which has been revisited in recent years and is more sensitive to retrocochlear lesions (Schmidt et al, 2024;Wasmann et al, 2018).…”

Tone Decay Reconsidered: Preliminary Results of a Prospective Study in Hearing-Aid Users with Moderate to Severe Hearing Loss

“…Wable et al [36] concluded that TD might facilitate further study of the condition of the auditory system in CI recipients as well as help to follow up on possible retrocochlear damage and to link TD to neural survival. Wasman et al [37] highlighted the potential use of TDTs to explain the spread of outcomes in CI recipients but, because of the small number of study participants, they did not draw clear conclusions. It appears that, together with TD in CI recipients, the preoperative assessment of TD can contribute to a better understanding of the above relationships.…”

“…If preoperative TD also partially explains the variability in word recognition with CI, then it should be included in future studies. In the past, TDTs were already performed in CI recipients [36,37]. Wable et al [36] concluded that TD might facilitate further study of the condition of the auditory system in CI recipients as well as help to follow up on possible retrocochlear damage and to link TD to neural survival.…”