Speech Understanding In Quiet Research Articles

Frequency-dependent loudness balancing in bimodal cochlear implant users

Conclusion In users of a cochlear implant (CI) and a hearing aid (HA) in contralateral ears, frequency-dependent loudness balancing between devices did, on average, not lead to improved speech understanding as compared to broadband balancing. However, nine out of 15 bimodal subjects showed significantly better speech understanding with either one of the fittings. Objectives Sub-optimal fittings and mismatches in loudness are possible explanations for the large individual differences seen in listeners using bimodal stimulation. Methods HA gain was adjusted for soft and loud input sounds in three frequency bands (0–548, 548–1000, and >1000 Hz) to match loudness with the CI. This procedure was compared to a simple broadband balancing procedure that reflected current clinical practice. In a three-visit cross-over design with 4 weeks between sessions, speech understanding was tested in quiet and in noise and questionnaires were administered to assess benefit in real world. Results Both procedures resulted in comparable HA gains. For speech in noise, a marginal bimodal benefit of 0.3 ± 4 dB was found, with large differences between subjects and spatial configurations. Speech understanding in quiet and in noise did not differ between the two loudness balancing procedures.

Quantification of Speech-in-Noise and Sound Localisation Abilities in Children with Unilateral Hearing Loss and Comparison to Normal Hearing Peers

The study objective was to quantify abilities of children with unilateral hearing loss (UHL) on measures that address known deficits for this population, i.e. speech understanding in quiet and noise, and sound localisation. Noise conditions varied by noise type and source location. Parent reports of real-world abilities were also obtained. Performance was compared to gender- and age-matched normal hearing (NH) peers. UHL performance was poorer and more varied compared to NH peers. Among the findings, age correlated with localisation ability for UHL but not NH participants. Low-frequency hearing in the better ear of UHL children was associated with performance in noise; however, there was no relation for NH children. Considerable variability was evident in the outcomes of children with UHL and needs to be understood as future treatment options are considered.

Music Perception in Adult Users of Cochlear Implants: A Brief Review

Although cochlear implants (CIs) can provide good speech understanding in quiet, in general, users of CIs have shown poor music perception performance, particularly with regard to pitch (and hence melody). This is primarily due to the limited ability of CI processing strategies and electric stimulation to provide place pitch and fine structure information from the original input signal to the auditory nervous system of the user. Approaches such as current focusing, current steering, enhanced amplitude modulation cues, and optic stimulation have been shown or theorized to assist in music perception, as have musical training programs. This article is a brief review of research related to music perception in adults with CIs, specifically their rhythm, pitch, and melody perception performance; processing strategies that have been or are being developed which might improve their music perception performance; and music training programs that have been shown to improve their music perception performance.

Cochlear implantation and single-sided deafness.

Recently, more patients with single-sided deafness (SSD) have been undergoing cochlear implantation. We review recent studies and case reports to provide an overview of the efficacy of cochlear implants to rehabilitate patients with SSD with regards to sound localization, speech discrimination, and tinnitus suppression. There are a growing number of studies evaluating the effect of cochlear implantation for rehabilitation of the deficits associated with SSD over the past several years as more centers offer this treatment modality to patients with SSD. Although individual studies have few patients and are underpowered, the vast majority report improvement in sound localization, speech understanding in quiet and noise, and tinnitus. In some cases, the outcomes with cochlear implant appear superior to those achieved with other devices, including contralateral routing of sound devices and osseointegrated implants. Although cochlear implant is not a Food and Drug Administration-approved treatment for SSD, several recent studies show improvements in speech understanding, sound localization, and tinnitus. Because of the low number of cases, it is difficult to conclusively compare outcomes achieved with cochlear implants and those provided by other devices. However, on the basis of encouraging early results and the unique ability to restore binaural sound processing, a growing number of centers offer cochlear implants as treatment for SSD. Forthcoming studies will help define outcome expectations in different populations.

Is complex signal processing for bone conduction hearing aids useful?

ObjectivesTo establish whether complex signal processing is beneficial for users of bone anchored hearing aids.MethodsReview and analysis of two studies from our own group, each comparing a speech processor with basic digital signal processing (either Baha Divino or Baha Intenso) and a processor with complex digital signal processing (either Baha BP100 or Baha BP110 power). The main differences between basic and complex signal processing are the number of audiologist accessible frequency channels and the availability and complexity of the directional multi-microphone noise reduction and loudness compression systems.ResultsBoth studies show a small, statistically non-significant improvement of speech understanding in quiet with the complex digital signal processing. The average improvement for speech in noise is +0.9 dB, if speech and noise are emitted both from the front of the listener. If noise is emitted from the rear and speech from the front of the listener, the advantage of the devices with complex digital signal processing as opposed to those with basic signal processing increases, on average, to +3.2 dB (range +2.3 … +5.1 dB, p ≤ 0.0032).DiscussionComplex digital signal processing does indeed improve speech understanding, especially in noise coming from the rear. This finding has been supported by another study, which has been published recently by a different research group.ConclusionsWhen compared to basic digital signal processing, complex digital signal processing can increase speech understanding of users of bone anchored hearing aids. The benefit is most significant for speech understanding in noise.

Influence of Loudness Compression on Hearing with Bone Anchored Hearing Implants

Bone Anchored Hearing Implants (BAHI) are routinely used in patients with conductive or mixed hearing loss, e.g. if conventional air conduction hearing aids cannot be used. New sound processors and new fitting software now allow the adjustment of parameters such as loudness compression ratios or maximum power output separately. Today it is unclear, how the choice of these parameters influences aided speech understanding in BAHI users. In this prospective experimental study, the effect of varying the compression ratio and lowering the maximum power output in a BAHI were investigated. Twelve experienced adult subjects with a mixed hearing loss participated in this study. Four different compression ratios (1.0; 1.3; 1.6; 2.0) were tested along with two different maximum power output settings, resulting in a total of eight different programs. Each participant tested each program during two weeks. A blinded Latin square design was used to minimize bias. For each of the eight programs, speech understanding in quiet and in noise was assessed. For speech in quiet, the Freiburg number test and the Freiburg monosyllabic word test at 50, 65, and 80 dB SPL were used. For speech in noise, the Oldenburg sentence test was administered. Speech understanding in quiet and in noise was improved significantly in the aided condition in any program, when compared to the unaided condition. However, no significant differences were found between any of the eight programs. In contrast, on a subjective level there was a significant preference for medium compression ratios of 1.3 to 1.6 and higher maximum power output.

Speech understanding with a new implant technology: a comparative study with a new nonskin penetrating Baha system.

Objective. To compare hearing and speech understanding between a new, nonskin penetrating Baha system (Baha Attract) to the current Baha system using a skin-penetrating abutment. Methods. Hearing and speech understanding were measured in 16 experienced Baha users. The transmission path via the abutment was compared to a simulated Baha Attract transmission path by attaching the implantable magnet to the abutment and then by adding a sample of artificial skin and the external parts of the Baha Attract system. Four different measurements were performed: bone conduction thresholds directly through the sound processor (BC Direct), aided sound field thresholds, aided speech understanding in quiet, and aided speech understanding in noise. Results. The simulated Baha Attract transmission path introduced an attenuation starting from approximately 5 dB at 1000 Hz, increasing to 20–25 dB above 6000 Hz. However, aided sound field threshold shows smaller differences and aided speech understanding in quiet and in noise does not differ significantly between the two transmission paths. Conclusion. The Baha Attract system transmission path introduces predominately high frequency attenuation. This attenuation can be partially compensated by adequate fitting of the speech processor. No significant decrease in speech understanding in either quiet or in noise was found.

Hearing Performance With 2 Different High-Power Sound Processors for Osseointegrated Auditory Implants

To compare speech understanding of the BAHA BP110 and BAHA Intenso sound processors. Prospective experimental study. Tertiary referral center. Twenty experienced user of osseointegrated auditory implants with conductive or mixed hearing loss. In a first session, half of the participants were fitted with an Intenso, the other half with a BP110. After 1 month of use, aided speech understanding in quiet and in noise was measured, and the other test processor was fitted. One month later, speech understanding with the second sound processor was assessed. Speech understanding in quiet and in noise, with noise arriving either from the front, the rear, or the side of the user with the osseointegrated bone conductor. Significant improvements were found for both processors for speech understanding in quiet (+9.6 to +34.8 percent points; p = 0.02 to 0.001) and in noise (+6.2 to +13.8 dB, p < 0.001). No significant differences were found between the 2 devices for speech in quiet. For noise from the rear, subjects were able to understand speech at signal-to-noise ratios which were lower (less favorable) by -5.1 dB (p < 0.001) when compared with the Intenso. Speech understanding is substantially improved by both devices, with no significant differences between the sound processors in quiet. In noise, speech understanding is significantly better with the BP110 when compared to the Intenso for noise from the rear.

Neural representation in the auditory midbrain of the envelope of vocalizations based on a peripheral ear model

The auditory midbrain implant (AMI) consists of a single shank array (20 sites) for stimulation along the tonotopic axis of the central nucleus of the inferior colliculus (ICC) and has been safely implanted in deaf patients who cannot benefit from a cochlear implant (CI). The AMI improves lip-reading abilities and environmental awareness in the implanted patients. However, the AMI cannot achieve the high levels of speech perception possible with the CI. It appears the AMI can transmit sufficient spectral cues but with limited temporal cues required for speech understanding. Currently, the AMI uses a CI-based strategy, which was originally designed to stimulate each frequency region along the cochlea with amplitude-modulated pulse trains matching the envelope of the bandpass-filtered sound components. However, it is unclear if this type of stimulation with only a single site within each frequency lamina of the ICC can elicit sufficient temporal cues for speech perception. At least speech understanding in quiet is still possible with envelope cues as low as 50 Hz. Therefore, we investigated how ICC neurons follow the bandpass-filtered envelope structure of natural stimuli in ketamine-anesthetized guinea pigs. We identified a subset of ICC neurons that could closely follow the envelope structure (up to ß100 Hz) of a diverse set of species-specific calls, which was revealed by using a peripheral ear model to estimate the true bandpass-filtered envelopes observed by the brain. Although previous studies have suggested a complex neural transformation from the auditory nerve to the ICC, our data suggest that the brain maintains a robust temporal code in a subset of ICC neurons matching the envelope structure of natural stimuli. Clinically, these findings suggest that a CI-based strategy may still be effective for the AMI if the appropriate neurons are entrained to the envelope of the acoustic stimulus and can transmit sufficient temporal cues to higher centers.

Comparison of 2 Implantable Bone Conduction Devices in Patients With Single-Sided Deafness Using a Daily Alternating Method

Comparison of the auditory and subjective capabilities of 2 implantable bone conduction devices BAHA Divino sound processor (Divino) and the BAHA BP100 sound processor (BP100) using a daily alternating method. Open prospective comparative trial. Tertiary referral otology and neurotology center. Ten patients with single-sided deafness (SSD) using a Divino for more than 1 year. The patients with SSD changed to the BP100 for 1 week, and then underwent an evaluation period of 18 days switching between BP100 and Divino on a daily alternating basis. On a scale from 0 to 10, patients rated their quality of hearing daily with both devices concerning overall satisfaction, clearness of sound, and effort of listening in background noise. For the total duration of the trial, the spatial hearing questionnaire (SHQ) and the abbreviated profile of hearing aid benefit (APHAB) were administered. In the unaided condition and with Divino at baseline and aided with BP100 after the evaluation period, adaptive speech in quiet and in noise testing was performed with speech and noise coming from different azimuth angles. Subjective rating in a diary, APHAB, SHQ, and aided speech in quiet and speech in noise. The diary shows significant improvement on all subscales with BP100 in comparison with Divino. These differences did not change significantly during 18 days. On the APHAB, listening in background noise and in reverberant conditions was rated significantly better with the BP100. The SHQ shows a significant difference between both devices on all subscales except for source localization and speech understanding in quiet. Speech audiometry showed a significant head shadow benefit with both implantable bone conduction devices (median [Q1, Q3]: Divino = 2.67 dB [0.33, 1.51], BP100 = 2.83 dB [4.08, 3.83]). There was no significant difference found between both devices. Both the Divino and the BP100 reduce the handicap experienced by patients with SSD. Subjective assessment using a daily alternating method shows higher overall hearing capabilities with BP100. Results of the questionnaires are similar. Speech audiometry in noise does not reveal a statistically significant difference between both devices. A daily alternating method can provide useful information for both the patient and the audiologist because objective measurements do not show any statistically significant differences between patients. In our opinion, daily alternation of devices is a useful method to compare different devices.

Optimization of Programming Parameters in Children with the Advanced Bionics Cochlear Implant

Cochlear implants provide access to soft intensity sounds and therefore improved audibility for children with severe-to-profound hearing loss. Speech processor programming parameters, such as threshold (or T-level), input dynamic range (IDR), and microphone sensitivity, contribute to the recipient's program and influence audibility. When soundfield thresholds obtained through the speech processor are elevated, programming parameters can be modified to improve soft sound detection. Adult recipients show improved detection for low-level sounds when T-levels are set at raised levels and show better speech understanding in quiet when wider IDRs are used. Little is known about the effects of parameter settings on detection and speech recognition in children using today's cochlear implant technology. The overall study aim was to assess optimal T-level, IDR, and sensitivity settings in pediatric recipients of the Advanced Bionics cochlear implant. Two experiments were conducted. Experiment 1 examined the effects of two T-level settings on soundfield thresholds and detection of the Ling 6 sounds. One program set T-levels at 10% of most comfortable levels (M-levels) and another at 10 current units (CUs) below the level judged as "soft." Experiment 2 examined the effects of IDR and sensitivity settings on speech recognition in quiet and noise. Participants were 11 children 7-17 yr of age (mean 11.3) implanted with the Advanced Bionics High Resolution 90K or CII cochlear implant system who had speech recognition scores of 20% or greater on a monosyllabic word test. Two T-level programs were compared for detection of the Ling sounds and frequency modulated (FM) tones. Differing IDR/sensitivity programs (50/0, 50/10, 70/0, 70/10) were compared using Ling and FM tone detection thresholds, CNC (consonant-vowel nucleus-consonant) words at 50 dB SPL, and Hearing in Noise Test for Children (HINT-C) sentences at 65 dB SPL in the presence of four-talker babble (+8 signal-to-noise ratio). Outcomes were analyzed using a paired t-test and a mixed-model repeated measures analysis of variance (ANOVA). T-levels set 10 CUs below "soft" resulted in significantly lower detection thresholds for all six Ling sounds and FM tones at 250, 1000, 3000, 4000, and 6000 Hz. When comparing programs differing by IDR and sensitivity, a 50 dB IDR with a 0 sensitivity setting showed significantly poorer thresholds for low frequency FM tones and voiced Ling sounds. Analysis of group mean scores for CNC words in quiet or HINT-C sentences in noise indicated no significant differences across IDR/sensitivity settings. Individual data, however, showed significant differences between IDR/sensitivity programs in noise; the optimal program differed across participants. In pediatric recipients of the Advanced Bionics cochlear implant device, manually setting T-levels with ascending loudness judgments should be considered when possible or when low-level sounds are inaudible. Study findings confirm the need to determine program settings on an individual basis as well as the importance of speech recognition verification measures in both quiet and noise. Clinical guidelines are suggested for selection of programming parameters in both young and older children.

Improvements in Speech Perception after the Upgrade from the TEMPO+ to the OPUS 2 Audio Processor

Objective: To assess if speech perception improves after the upgrade from the TEMPO+ to the OPUS 2 processor. Method: In this retrospective study, 45 subjects (54 ears) implanted with a cochlear implant were upgraded from the TEMPO+ (continuous interleaved sampling + coding strategy) to the OPUS 2 processor (fine structure processing). Before the upgrade, patients were tested with the Freiburg monosyllable (FM) and the Hochmair-Schulz-Moser (HSM) sentence test in quiet and in noise. Four weeks after the upgrade, subjects were again assessed with the same tests. Results: In quiet, mean FM results improved from 62.0% (±21.3%) to 77.8% (±15.2%) and HSM sentences from 69.9% (±26.1%) to 77.9% (±22.1%). In noise, mean FM results improved from 27.3% (±17.1%) to 52.1% (±18.6%) and HSM sentences from 40.4% (±29.1%) to 58.0% (±26.1%). The upgrade to the OPUS 2 was statistically very significant for all speech perception tests (p < 0.001). Additionally, subjects stated that the OPUS 2 initially sounded ‘awkward’ but that quality and speech perception improved after a certain adaptation time. Conclusion: Speech understanding in quiet and noise significantly improved with the OPUS 2 in all speech perception tests.

Digit Training in Noise Can Improve Cochlear Implant Users' Speech Understanding in Noise

While auditory training in quiet has been shown to improve cochlear implant (CI) users' speech understanding in quiet, it is unclear whether training in noise will benefit speech understanding in noise. The present study investigated whether auditory training could improve CI users' speech recognition in noise and whether training with familiar stimuli in an easy listening task (closed-set digit recognition) would improve recognition of unfamiliar stimuli in a more difficult task (open-set sentence recognition). CI users' speech understanding in noise was assessed before, during, and after auditory training with a closed-set recognition task (digits identification) in speech babble. Before training was begun, recognition of digits, Hearing in Noise Test (HINT) sentences, and IEEE sentences presented in steady speech-shaped noise or multitalker speech babble was repeatedly measured to establish a stable estimate of baseline performance. After completing baseline measures, participants trained at home on their personal computers using custom software for approximately 30 mins/day, 5 days/wk, for 4 wks, for a total of 10 hrs of training. Participants were trained only to identify random sequences of three digits presented in speech babble, using a closed-set task. During training, the signal-to-noise ratio was adjusted according to subject performance; auditory and visual feedback was provided. Recognition of digits, HINT sentences, and IEEE sentences in steady noise and speech babble was remeasured after the second and fourth week of training. Training was stopped after the fourth week, and subjects returned to the laboratory 1 mo later for follow-up testing to see whether any training benefits had been retained. Mean results showed that the digit training in babble significantly improved digit recognition in babble (which was trained) and in steady noise (which was not trained). The training benefit generalized to improved HINT and IEEE sentence recognition in both types of noise. Training benefits were largely retained in follow-up measures made 1 mo after training was stopped. The results demonstrated that auditory training in noise significantly improved CI users' speech performance in noise, and that training with simple stimuli using an easy closed-set listening task improved performance with difficult stimuli and a difficult open-set listening task.

Comparisons of Sound Processors Based on Osseointegrated Implants in Patients With Conductive or Mixed Hearing Loss

To compare the patient benefit of the Bone-Anchored Hearing Aid (Baha) Divino and the Baha BP100 sound processors. Prospective experimental study. Tertiary referral center. Twenty experienced Baha Divino users with conductive or mixed hearing loss. Speech understanding in quiet and in noise was measured in unaided conditions and with the subjects' own Divino sound processors. Speech in noise was tested with the noise arriving either from the front or from the back of the subjects. Then, participants were fitted with BP100 sound processors. After 3 months of use, all speech tests were repeated with the new sound processor along with a subset of the tests from the first session to assess learning or training effects. The Abbreviated Profile of Hearing Aid Benefit (APHAB) questionnaires were administered at 0 and at 3 months. Aided speech understanding in quiet and in noise. No significant differences were found between the two devices regarding speech understanding in quiet. Speech understanding in noise was improved, on average, by +1.0 to +2.3 dB with the BP100 when compared to the Divino. No significant learning effects were found. Subjective ratings assessed by the Abbreviated Profile of Hearing Aid Benefit (APHAB) questionnaire showed statistically significantly better scores for the BP100 for noisy or reverberant environments, when compared with the Divino. The performance of both devices is similar for speech understanding in quiet. Speech understanding in noise is significantly better with the Baha BP100 than with the Baha Divino, presumably as a result of the improved signal processing.

Spectral cues for understanding speech in quiet and in noise

thresholds observed at 0.25 and 0.50 peaks/octave (Saoji et al., 2009). The bandwidth and audio-frequency range of the noise band carrier has little effect on SMD thresholds of NH listeners. That is, sensitivity to 1cycle/octave modulation obtained to a four-octave noiseband is not likely different than that obtained to a one-octave noiseband tested at the upper or lower range of the original broadband stimulus. In the present study, SMD thresholds were obtained to noiseband stimuli of differentbandwidthsand audio-frequency regionsat different spectral modulation frequencies. The SMD thresholds were compared with the listener’s speech understanding scores to determine the relationship between SMD thresholds and performance. The goal was to determine the spectral cues (i.e. spectral modulation frequencies and audio-frequency ranges) required to model speech understanding in quiet and in noise.

Speech intelligibility in noise for adult and children users of cochlear implants.

Even though high levels of speech understanding in quiet can be developed postimplantation, speech recognition in noise is an especially challenging task for cochlear implant (CI) users. This study examined whether adult and children CI users benefit from signal clarity and contextual‐semantic information to improve their speech recognition in noise. Ten adult and ten children CI users, and ten adults and ten children with normal hearing participated in sentence‐in‐noise listening tests. They heard sentences in which final word varied in predictability, i.e., high versus low semantic context, produced by one female and one male talker in conversational or clear speaking styles. The goal was to assess the effect of age and the length of experience with using cochlear implants on the ability to utilize the compensatory information at higher levels of speech processing independently and in combination with the acoustic‐phonetic enhancements in speech perception. This research will allow us to explore the interaction between lower‐level sensory and higher‐level cognitive factors that affect speech processing in noise for adults and children with cochlear implants. The results of this study add to our current understanding of the development of speech recognition for individuals with cochlear implants and with normal hearing.

Effect of acoustic‐phonetic and semantic enhancements on speech recognition for children with cochlear implants.

With early implantation and intense rehabilitation, children with cochlear implants are able to develop high levels of speech understanding in quiet. However, speech recognition in noise remains a challenging task for this listener group. In this study, we examine how signal clarity interacts with the use of compensatory information at higher levels in determining speech recognition levels for children with cochlear implants and children with normal hearing. Specifically, we explore the effect of clear speech, a distinct, intelligibility‐enhancing speaking style, and of contextual‐semantic information on speech recognition in noise. One hundred and twenty sentences in which final word varied in predictability, i.e., high versus low semantic context, and which were produced in conversational and clear speech by one female and one male talker were embedded in noise. Twenty children between 5 and 12 years of age participated in a sentence‐in‐noise perception test. The goal was to examine the level of signal clarity needed to take advantage of the contextual information for children with cochlear implants compared to children with normal hearing. This research will allow us to explore the interaction between lower‐level sensory and higher‐level cognitive factors that affect speech processing in these two target groups of children.

Cochlear implant patients' speech understanding in background noise: effect of mismatch between electrode assigned frequencies and perceived pitch

To assess the electrode pitch function in a series of adults with postlingually implanted cochlear implants and with contralateral residual hearing, in order to investigate the correlation between the degree of frequency map mismatch and the subjects' speech understanding in quiet and noisy conditions. Case series. Seven postlingually deafened adults with cochlear implants, all with detectable contralateral residual hearing. Subjects' electrode pitch function was assessed by means of a pitch-matching test, in which they were asked to match an acoustic pitch (pure tones delivered to the non-implanted ear by an audiometer) to a perceived 'pitch' elicited by stimulation of the cochlear implant electrodes. A mismatch score was calculated for each subject. Speech recognition was tested using lists of sentences presented in quiet conditions and at +10, 0 and 5 dB HL signal-to-noise ratio levels (i.e. noise 10 dB HL lower than signal, noise as loud as signal and noise 5 dB HL higher than signal, respectively). Correlations were assessed using a linear regression model, with significance set at p < 0.05. All patients presented some degree of mismatch between the acoustic frequencies assigned to their implant electrodes and the pitch elicited by stimulation of the same electrode, with high between-individual variability. A significant correlation (p < 0.005) was found between mismatch and speech recognition scores at +10 and 0 dB HL signal-to-noise ratio levels (r2 = 0.91 and 0.89, respectively). The mismatch between frequencies allocated to electrodes and the pitch perceived on stimulation of the same electrodes could partially account for our subjects' difficulties with speech understanding in noisy conditions. We suggest that these subjects could benefit from mismatch correction, through a procedure allowing individualised reallocation of frequency bands to electrodes.

Bone-Anchored Hearing Aids

To investigate correlations between preoperative hearing thresholds and postoperative aided thresholds and speech understanding of users of Bone-anchored Hearing Aids (BAHA). Such correlations may be useful to estimate the postoperative outcome with BAHA from preoperative data. Retrospective case review. Tertiary referral center. : Ninety-two adult unilaterally implanted BAHA users in 3 groups: (A) 24 subjects with a unilateral conductive hearing loss, (B) 38 subjects with a bilateral conductive hearing loss, and (C) 30 subjects with single-sided deafness. Preoperative air-conduction and bone-conduction thresholds and 3-month postoperative aided and unaided sound-field thresholds as well as speech understanding using German 2-digit numbers and monosyllabic words were measured and analyzed. Correlation between preoperative air-conduction and bone-conduction thresholds of the better and of the poorer ear and postoperative aided thresholds as well as correlations between gain in sound-field threshold and gain in speech understanding. Aided postoperative sound-field thresholds correlate best with BC threshold of the better ear (correlation coefficients, r2 = 0.237 to 0.419, p = 0.0006 to 0.0064, depending on the group of subjects). Improvements in sound-field threshold correspond to improvements in speech understanding. When estimating expected postoperative aided sound-field thresholds of BAHA users from preoperative hearing thresholds, the BC threshold of the better ear should be used. For the patient groups considered, speech understanding in quiet can be estimated from the improvement in sound-field thresholds.

Melodic Contour Identification and Music Perception by Cochlear Implant Users

Research and outcomes with cochlear implants (CIs) have revealed a dichotomy in the cues necessary for speech and music recognition. CI devices typically transmit 16-22 spectral channels, each modulated slowly in time. This coarse representation provides enough information to support speech understanding in quiet and rhythmic perception in music, but not enough to support speech understanding in noise or melody recognition. Melody recognition requires some capacity for complex pitch perception, which in turn depends strongly on access to spectral fine structure cues. Thus, temporal envelope cues are adequate for speech perception under optimal listening conditions, while spectral fine structure cues are needed for music perception. In this paper, we present recent experiments that directly measure CI users' melodic pitch perception using a melodic contour identification (MCI) task. While normal-hearing (NH) listeners' performance was consistently high across experiments, MCI performance was highly variable across CI users. CI users' MCI performance was significantly affected by instrument timbre, as well as by the presence of a competing instrument. In general, CI users had great difficulty extracting melodic pitch from complex stimuli. However, musically experienced CI users often performed as well as NH listeners, and MCI training in less-experienced subjects greatly improved performance. With fixed constraints on spectral resolution, such as occurs with hearing loss or an auditory prosthesis, training and experience can provide considerable improvements in music perception and appreciation.