Consonant Identification Research Articles

Comparison of Gated Audiovisual Speech Identification in Elderly Hearing Aid Users and Elderly Normal-Hearing Individuals: Effects of Adding Visual Cues to Auditory Speech Stimuli.

The present study compared elderly hearing aid (EHA) users (n = 20) with elderly normal-hearing (ENH) listeners (n = 20) in terms of isolation points (IPs, the shortest time required for correct identification of a speech stimulus) and accuracy of audiovisual gated speech stimuli (consonants, words, and final words in highly and less predictable sentences) presented in silence. In addition, we compared the IPs of audiovisual speech stimuli from the present study with auditory ones extracted from a previous study, to determine the impact of the addition of visual cues. Both participant groups achieved ceiling levels in terms of accuracy in the audiovisual identification of gated speech stimuli; however, the EHA group needed longer IPs for the audiovisual identification of consonants and words. The benefit of adding visual cues to auditory speech stimuli was more evident in the EHA group, as audiovisual presentation significantly shortened the IPs for consonants, words, and final words in less predictable sentences; in the ENH group, audiovisual presentation only shortened the IPs for consonants and words. In conclusion, although the audiovisual benefit was greater for EHA group, this group had inferior performance compared with the ENH group in terms of IPs when supportive semantic context was lacking. Consequently, EHA users needed the initial part of the audiovisual speech signal to be longer than did their counterparts with normal hearing to reach the same level of accuracy in the absence of a semantic context.

Reducing Channel Interaction Through Cochlear Implant Programming May Improve Speech Perception: Current Focusing and Channel Deactivation.

Speech perception among cochlear implant (CI) listeners is highly variable. High degrees of channel interaction are associated with poorer speech understanding. Two methods for reducing channel interaction, focusing electrical fields, and deactivating subsets of channels were assessed by the change in vowel and consonant identification scores with different program settings. The main hypotheses were that (a) focused stimulation will improve phoneme recognition and (b) speech perception will improve when channels with high thresholds are deactivated. To select high-threshold channels for deactivation, subjects’ threshold profiles were processed to enhance the peaks and troughs, and then an exclusion or inclusion criterion based on the mean and standard deviation was used. Low-threshold channels were selected manually and matched in number and apex-to-base distribution. Nine ears in eight adult CI listeners with Advanced Bionics HiRes90k devices were tested with six experimental programs. Two, all-channel programs, (a) 14-channel partial tripolar (pTP) and (b) 14-channel monopolar (MP), and four variable-channel programs, derived from these two base programs, (c) pTP with high- and (d) low-threshold channels deactivated, and (e) MP with high- and (f) low-threshold channels deactivated, were created. Across subjects, performance was similar with pTP and MP programs. However, poorer performing subjects (scoring < 62% correct on vowel identification) tended to perform better with the all-channel pTP than with the MP program (1 > 2). These same subjects showed slightly more benefit with the reduced channel MP programs (5 and 6). Subjective ratings were consistent with performance. These finding suggest that reducing channel interaction may benefit poorer performing CI listeners.

Correlations Between Pitch and Phoneme Perception in Cochlear Implant Users and Their Normal Hearing Peers.

This study examined correlations between pitch and phoneme perception for nine cochlear implant users and nine normal hearing listeners. Pure tone frequency discrimination thresholds were measured for frequencies of 500, 1000, and 2000 Hz. Complex tone fundamental frequency (F0) discrimination thresholds were measured for F0s of 110, 220, and 440 Hz. The effects of amplitude and frequency roving were measured under the rationale that individuals who are robust to such perturbations would perform better on phoneme perception measures. Phoneme identification was measured using consonant and vowel materials in quiet, in stationary speech-shaped noise (SSN), in spectrally notched SSN, and in temporally gated SSN. Cochlear implant pure tone frequency discrimination thresholds ranged between 1.5 and 9.9 %, while cochlear implant complex tone F0 discrimination thresholds ranged between 2.6 and 28.5 %. On average, cochlear implant users had 5.3 dB of masking release for consonants and 8.4 dB of masking release for vowels when measured in temporally gated SSN compared to stationary SSN. Correlations with phoneme identification measures were generally higher for complex tone discrimination measures than for pure tone discrimination measures. Correlations with phoneme identification measures were also generally higher for pitch perception measures that included amplitude and frequency roving. The strongest correlations were observed for measures of complex tone F0 discrimination with phoneme identification in temporally gated SSN. The results of this study suggest that musical training or signal processing strategies that improve F0 discrimination should improve consonant identification in fluctuating noise.

Effects of Nonlinear Frequency Compression on ACC Amplitude and Listener Performance.

Nonlinear frequency compression is a signal processing technique used to increase the audibility of high-frequency speech sounds for hearing aid users with sloping, high-frequency hearing loss. However, excessive compression ratios may reduce spectral contrast between sounds and negatively impact speech perception. This is of particular concern in infants and young children who may not be able to provide feedback about frequency compression settings. This study explores the use of an objective cortical auditory evoked potential that is sensitive to changes in spectral contrast, the acoustic change complex (ACC), in the verification of frequency compression parameters. ACC responses were recorded from adult listeners to a spectral ripple contrast stimulus that was processed using a range of frequency compression ratios (1:1, 1.5:1, 2:1, 3:1, and 4:1). Vowel identification, consonant identification, speech recognition in noise (QuickSIN), and behavioral ripple discrimination thresholds were also measured under identical frequency compression conditions. In Experiment 1, these tasks were completed in 10 adults with normal hearing. In Experiment 2, these same tasks were repeated in 10 adults with sloping, high-frequency hearing loss. Repeated measures analysis of variance was completed for each task and each group with frequency compression ratio as the within-subjects factor. Increasing the compression ratio did not affect vowel identification for the normal hearing group but did cause a significant decrease in vowel identification for the hearing-impaired listeners. Increases in compression ratio were associated with significant decrements in ACC amplitudes, consonant identification scores, ripple discrimination thresholds, and speech perception in noise scores for both groups of listeners. The ACC response, like speech and nonspeech perceptual measures, is sensitive to frequency compression ratio. Additional study is needed to establish optimal stimulus and recording parameters for the clinical application of this measure in the verification of hearing aid frequency compression settings.

Listener characteristics and the perception of speech in noise

Speech communication is often made difficult by the presence of background noise. Much research on the perception of noise-masked speech has focused on the masking of phonetic information by different types of noise (e.g., white noise, speech-shaped noise, temporally modulated noise, multi-talker babble). The present work focuses on the relationships between some cognitive characteristics of listeners and accuracy in the identification of noise-masked consonants. 37 listeners identified numerous tokens of each of 4 consonants (p, b, f, v) in CV syllables produced by 8 talkers (4 male, 4 female) masked by 10-talker babble. Listeners also completed a number of tasks designed to measure selective attention: two dichotic listening tasks and two non-speech discrimination tasks. On each trial of the dichotic listening tasks, one or the other ear was cued visually (i.e., “right ear” or “left ear”), after which the listener indicated the talker sex or the consonant in the target ear, depending on task. In the two non-speech tasks, listeners discriminated either the frequency or the duration of broadband target noise bursts embedded in temporally modulated background noise. Analyses indicate a positive relationship between noise-masked speech accuracy and performance on the dichotic consonant identification and complex non-speech discrimination tasks.

Relative contributions of vowels and consonants in recognizing isolated Mandarin words

This study investigated the relative contributions of vowels and consonants in recognizing isolated Mandarin words. Normal-hearing native-Mandarin listeners were instructed to recognize isolated Mandarin words and identify consonants, vowels and tones with stimuli synthesized to contain different proportions of consonant or vowel segments, including five conditions of consonant-only, vowel-only, consonant or vowel plus consonant–vowel (C–V) transition, and C–V transition. The recognition score of the vowel-only Mandarin words was significantly higher than that of the consonant-only words; and word recognition scores had a higher correlation with vowel identification scores than consonant identification scores. Moreover, adding a small portion of C–V transition significantly improved the recognition score of the consonant-only Mandarin words. In the conditions of C–V transition and consonant plus C–V transition, the duration of preserved portion predicted modestly well the scores of isolated word recognition, and vowel, consonant and lexical tone identification in Mandarin. These findings suggest that there is a greater contribution of vowels than consonants to isolated word recognition in Mandarin, which is different from previous outcomes in English.

Trimodal speech perception: how residual acoustic hearing supplements cochlear-implant consonant recognition in the presence of visual cues.

As cochlear implant (CI) acceptance increases and candidacy criteria are expanded, these devices are increasingly recommended for individuals with less than profound hearing loss. As a result, many individuals who receive a CI also retain acoustic hearing, often in the low frequencies, in the nonimplanted ear (i.e., bimodal hearing) and in some cases in the implanted ear (i.e., hybrid hearing) which can enhance the performance achieved by the CI alone. However, guidelines for clinical decisions pertaining to cochlear implantation are largely based on expectations for postsurgical speech-reception performance with the CI alone in auditory-only conditions. A more comprehensive prediction of postimplant performance would include the expected effects of residual acoustic hearing and visual cues on speech understanding. An evaluation of auditory-visual performance might be particularly important because of the complementary interaction between the speech information relayed by visual cues and that contained in the low-frequency auditory signal. The goal of this study was to characterize the benefit provided by residual acoustic hearing to consonant identification under auditory-alone and auditory-visual conditions for CI users. Additional information regarding the expected role of residual hearing in overall communication performance by a CI listener could potentially lead to more informed decisions regarding cochlear implantation, particularly with respect to recommendations for or against bilateral implantation for an individual who is functioning bimodally. Eleven adults 23 to 75 years old with a unilateral CI and air-conduction thresholds in the nonimplanted ear equal to or better than 80 dB HL for at least one octave frequency between 250 and 1000 Hz participated in this study. Consonant identification was measured for conditions involving combinations of electric hearing (via the CI), acoustic hearing (via the nonimplanted ear), and speechreading (visual cues). The results suggest that the benefit to CI consonant-identification performance provided by the residual acoustic hearing is even greater when visual cues are also present. An analysis of consonant confusions suggests that this is because the voicing cues provided by the residual acoustic hearing are highly complementary with the mainly place-of-articulation cues provided by the visual stimulus. These findings highlight the need for a comprehensive prediction of trimodal (acoustic, electric, and visual) postimplant speech-reception performance to inform implantation decisions. The increased influence of residual acoustic hearing under auditory-visual conditions should be taken into account when considering surgical procedures or devices that are intended to preserve acoustic hearing in the implanted ear. This is particularly relevant when evaluating the candidacy of a current bimodal CI user for a second CI (i.e., bilateral implantation). Although recent developments in CI technology and surgical techniques have increased the likelihood of preserving residual acoustic hearing, preservation cannot be guaranteed in each individual case. Therefore, the potential gain to be derived from bilateral implantation needs to be weighed against the possible loss of the benefit provided by residual acoustic hearing.

Talker variation in the perception of speech in noise

Speech communication commonly occurs in the presence of noise. Research on the perception of speech in noise has largely focused on the perceptual availability of target phonetic information in the presence of various noise maskers (e.g., white noise, speech-shaped noise, temporally modulated noise, and multi-talker babble). Previous work has shown that a glimpsing model and a modified Articular Index model closely approximate overall accuracy of noise-masked speech perception (Cooke, 2006, JASA; Allen, 2005; JASA). Some recent work has focused on variation in confusion patterns across listeners (Silbert, 2012, JASA, 2014, Lab. Phon.) and on difference in perceptual error rates across and within consonant categories (Toscano & Allen, forthcoming, JSLHR). The present work focuses on listener and stimulus-talker variation in the identification of consonants. Eleven listeners identified numerous tokens of each of four consonants (t, d, s, z) in CV syllables produced by 20 talkers (10 male, 10 female) masked ...

Relation between measures of psychoacoustic abilities and masking release for unprocessed, envelope, and temporal fine-structure speech in listeners with normal and impaired hearing

Léger et al. [J. Acoust. Soc. Am. 135, 2160, 2014] studied masking release in normal-hearing and hearing-impaired listeners using unprocessed speech and speech processed to convey envelope (ENV) or temporal fine-structure (TFS) cues. Consonant identification scores in speech-shaped background noise (continuous and square-wave interrupted at a rate of 10 Hz) indicated a substantial masking release (MR, better performance in the interrupted noise) for all speech types for normal-hearing listeners but only for the TFS speech in most hearing-impaired listeners. The current study was concerned with relating consonant identification scores and masking release to SRTs for sentences in both types of noise as well as to measurements of basic psychoacoustic abilities. These measures included absolute pure-tone detection thresholds, estimates of auditory bandwidth using a notched-noise procedure, and estimates of cochlear compression obtained using a forward-masking paradigm. For both unprocessed and ENV speech, intelligibility scores and MR were correlated with absolute thresholds and auditory bandwidths in the mid-frequency region (but not at a lower frequency). These correlations were less strong for TFS speech intelligibility and did not predict MR. Cochlear compression was not related to speech intelligibility when controlling for the effect of absolute thresholds. [Work supported by NIH R01 DC000117.]

The comparison of auditory capacity between bilinguals and monolinguals by consonant–vowel dichotic test

The purpose of the present study is investigation of differences in auditory capacity between bilinguals and monolinguals using the consonant–vowel (CV) dichotic perception test. Bilingualism is one well-studied in psychology and linguistics, with a number of studies revealing that exposure to two languages can lead to the changes in the central system. Auditory capacity refers to the ability to relay information in sound patterns to higher brain centers, with observed measures of auditory capacity reflecting the maximum amount of information that can be processed by the auditory system. The present study probed auditory capacity in 80 normal individuals, 40 bilinguals and 40 monolinguals. Members of the bilingual groups spoke either Turkish or Kurdish from birth and began learning Persian as a second language at or before 6 years of age. Listeners identified distinct consonants presented to each ear in a CV dichotic perception test. Consonant identification accuracy served as a measure of auditory capacity of individual listeners. Results indicated that auditory capacity was greater in the bilingual group. In general, higher scores were gained by bilinguals relative to monolinguals. Due to the large number of bilinguals, knowledge of the similarities and differences between bilinguals and monolinguals and investigation of the effects of second language on central auditory processing are important.

Temporal processing and speech perception in quiet and noise across different degrees of ANSD

Objective: The aim of the present study was to examine the effect of degree of temporal processing impairment in adult listeners with ANSD on speech perception measures. Study design: Forty-six listeners with ANSD and 30 normal hearing listeners participated in the study. Temporal resolution was measured using the Temporal Modulation Transfer Function (TMTF). Speech identification scores in quiet were measured for bisyllabic words and Speech Reception Threshold in noise (SRTn) was measured for words. Furthermore, consonant identification was measured for 20 VCV stimuli. Results: Listeners with ANSD performed significantly worse than normal hearing listeners in both temporal resolution and speech perception measures. Peak sensitivity and 3dB cut-off frequency were estimated for each individual in both groups from the TMTFs data using an exponential fitting function. The listeners with ANSD were subgrouped into mild, moderate and severe degrees based on peak sensitivity. As the degree of temporal processing impairment increased, speech identification scores reduced and SRTn increased systematically. Similarly, consonant identification decreased with increase in temporal processing impairment. Among phonemic features, manner of articulation was better perceived compared to voice and place of articulation. Conclusion: The high correlation between temporal processing ability and speech perception suggests that temporal processing measures may be a potential tool for assessing the severity of ANSD in adult listeners.

Lexical stress and stop bursts in Pitjantjatjara: Feature enhancement of neutralized apicals and the coronal/velar contrast

This study investigates duration and spectral properties of the stop burst for /p t ʈc k/, the five oral stops of Pitjantjatjara, a language of Central Australia. We focus on stressed vs. unstressed syllables, with stressed syllables also being word-initial in Pitjantjatjara. Notably, the contrast between the apico-alveolar /t/ and the medial apico-postalveolar (retroflex) /ʈ/ is neutralized in initial position, which is the stressed position. We label this neutralized apical /T/, and show that the stop burst for this prosodically prominent apical has an even higher spectral center of gravity than either of its non-neutralized counterparts. By contrast, the velar /k/ shows a lower spectral center of gravity in stressed position. We suggest that this reflects an enhancement of the feature [grave], with the apical being “lighter” and the velar being “darker” under stress (the bilabial and the palatal show relatively few spectral effects, due to acoustic and coarticulatory considerations respectively). However, the stressed apical /T/ does not have a longer stop burst duration in initial position, a result that is contrary to the other stop bursts examined here, and which goes against expected patterns of prosodic strengthening. We suggest that this is because a phonetic feature, short [burst duration], is an important cue to apical consonant identity in a system with many places of articulation.

Speech Perception in Older Hearing Impaired Listeners: Benefits of Perceptual Training

Hearing aids (HAs) only partially restore the ability of older hearing impaired (OHI) listeners to understand speech in noise, due in large part to persistent deficits in consonant identification. Here, we investigated whether adaptive perceptual training would improve consonant-identification in noise in sixteen aided OHI listeners who underwent 40 hours of computer-based training in their homes. Listeners identified 20 onset and 20 coda consonants in 9,600 consonant-vowel-consonant (CVC) syllables containing different vowels (/ɑ/, /i/, or /u/) and spoken by four different talkers. Consonants were presented at three consonant-specific signal-to-noise ratios (SNRs) spanning a 12 dB range. Noise levels were adjusted over training sessions based on d’ measures. Listeners were tested before and after training to measure (1) changes in consonant-identification thresholds using syllables spoken by familiar and unfamiliar talkers, and (2) sentence reception thresholds (SeRTs) using two different sentence tests. Consonant-identification thresholds improved gradually during training. Laboratory tests of d’ thresholds showed an average improvement of 9.1 dB, with 94% of listeners showing statistically significant training benefit. Training normalized consonant confusions and improved the thresholds of some consonants into the normal range. Benefits were equivalent for onset and coda consonants, syllables containing different vowels, and syllables presented at different SNRs. Greater training benefits were found for hard-to-identify consonants and for consonants spoken by familiar than unfamiliar talkers. SeRTs, tested with simple sentences, showed less elevation than consonant-identification thresholds prior to training and failed to show significant training benefit, although SeRT improvements did correlate with improvements in consonant thresholds. We argue that the lack of SeRT improvement reflects the dominant role of top-down semantic processing in processing simple sentences and that greater transfer of benefit would be evident in the comprehension of more unpredictable speech material.

A quantitative model of first language influence in second language consonant learning

Theoretical models argue that listeners’ perception of second language sounds is heavily influenced by their native language phonology, a prediction borne out by behavioural studies. However, we lack quantitative models capable of making more precise predictions of the way in which the first and second language sound systems interact. The current study introduces a computational modelling framework that permits comparison of different second language learning strategies which vary both in the degree of first language influence as well as in the manner in which second language input is combined with existing first language knowledge. Six different model variants were evaluated by comparison with behavioural data on a task involving the identification of intervocalic consonants of Castilian Spanish by Mandarin Chinese listeners. All approaches demonstrated a similar pattern of rapid improvement with exposure to that observed in listeners. However, approaches that made use of independent first and second language models made the best predictions. An approach that excluded first language influence both predicted lower listener identification levels in the initial stages of learning and higher scores in later stages, demonstrating that first language experience helps to bootstrap second language sound learning but ultimately hinders identification. However, modelling outcomes also demonstrate that no single approach can account for the identification patterns for all consonants, suggesting that learners deploy different approaches to the learning of individual sounds.

Age-group differences in speech identification despite matched audiometrically normal hearing: contributions from auditory temporal processing and cognition.

Hearing loss with increasing age adversely affects the ability to understand speech, an effect that results partly from reduced audibility. The aims of this study were to establish whether aging reduces speech intelligibility for listeners with normal audiograms, and, if so, to assess the relative contributions of auditory temporal and cognitive processing. Twenty-one older normal-hearing (ONH; 60–79 years) participants with bilateral audiometric thresholds ≤ 20 dB HL at 0.125–6 kHz were matched to nine young (YNH; 18–27 years) participants in terms of mean audiograms, years of education, and performance IQ. Measures included: (1) identification of consonants in quiet and in noise that was unmodulated or modulated at 5 or 80 Hz; (2) identification of sentences in quiet and in co-located or spatially separated two-talker babble; (3) detection of modulation of the temporal envelope (TE) at frequencies 5–180 Hz; (4) monaural and binaural sensitivity to temporal fine structure (TFS); (5) various cognitive tests. Speech identification was worse for ONH than YNH participants in all types of background. This deficit was not reflected in self-ratings of hearing ability. Modulation masking release (the improvement in speech identification obtained by amplitude modulating a noise background) and spatial masking release (the benefit obtained from spatially separating masker and target speech) were not affected by age. Sensitivity to TE and TFS was lower for ONH than YNH participants, and was correlated positively with speech-in-noise (SiN) identification. Many cognitive abilities were lower for ONH than YNH participants, and generally were correlated positively with SiN identification scores. The best predictors of the intelligibility of SiN were composite measures of cognition and TFS sensitivity. These results suggest that declines in speech perception in older persons are partly caused by cognitive and perceptual changes separate from age-related changes in audiometric sensitivity.

Identification of English consonants in intervocalic contexts in multispeaker babble noise by Japanese listeners: Correlation between English proficiency and consonant identification ability

Identification of English consonants in intervocalic contexts in multispeaker babble noise by Japanese listeners: Correlation between English proficiency and consonant identification ability

The Composition of the Phonological Consonant System and its Functioning in Lithuanian and French Languages

The aim of the article is to examine the composition of the phonological consonant system and its functioning in Lithuanian and French languages. We will describe the phonological consonant systems of both languages on two levels – syntagmatic and paradigmatic. On the syntagmatic level we will discuss the structure and regularities of explosive, implosive consonant distributions and inner consonant collocations. On the paradigmatic level we will focus on the paradigmatic consonant identification – peculiarities of consonant oppositions, their neutralization and the comparison of the inventory of differential features in the languages of our concern. In this work we will base ourselves only on the literary pronunciation of the French language. Colloquial French has its own peculiarities which determine the appearance of new structures of consonant collocations, therefore their description can be the object of another scholarly work. We will present French nouns without articles as to describe explosive consonant groups, it is most convenient to take a noun without an article. The structures and collocation regularities of consonant collocations are best reflected only in this form. Soft vowels and affricates which do not exist in the French language are not discussed in the article.

Perceptual compensation for the effects of reverberation on consonant identification: evidence from studies with monaural stimuli.

Mounting evidence suggests that listeners perceptually compensate for the adverse effects of reverberation in rooms when listening to speech monaurally. However, it is not clear whether the underlying perceptual mechanism would be at all effective in the high levels of stimulus uncertainty that are present in everyday listening. Three experiments investigated monaural compensation with a consonant identification task in which listeners heard different speech on each trial. Consonant confusions frequently arose when a greater degree of reverberation was added to a test-word than to its surrounding context, but compensation became apparent in conditions where the context reverberation was increased to match that of the test-word; here, the confusions were largely resolved. A second experiment shows that information from the test-word itself can also effect compensation. Finally, the time course of compensation was examined by applying reverberation to a portion of the preceding context; consonant identification improves as this portion increases in duration. These findings indicate a monaural compensation mechanism that is likely to be effective in everyday listening, allowing listeners to recalibrate as their reverberant environment changes.

Multisensory training can promote or impede visual perceptual learning of speech stimuli: visual-tactile vs. visual-auditory training

In a series of studies we have been investigating how multisensory training affects unisensory perceptual learning with speech stimuli. Previously, we reported that audiovisual (AV) training with speech stimuli can promote auditory-only (AO) perceptual learning in normal-hearing adults but can impede learning in congenitally deaf adults with late-acquired cochlear implants. Here, impeder and promoter effects were sought in normal-hearing adults who participated in lipreading training. In Experiment 1, visual-only (VO) training on paired associations between CVCVC nonsense word videos and nonsense pictures demonstrated that VO words could be learned to a high level of accuracy even by poor lipreaders. In Experiment 2, visual-auditory (VA) training in the same paradigm but with the addition of synchronous vocoded acoustic speech impeded VO learning of the stimuli in the paired-associates paradigm. In Experiment 3, the vocoded AO stimuli were shown to be less informative than the VO speech. Experiment 4 combined vibrotactile speech stimuli with the visual stimuli during training. Vibrotactile stimuli were shown to promote visual perceptual learning. In Experiment 5, no-training controls were used to show that training with visual speech carried over to consonant identification of untrained CVCVC stimuli but not to lipreading words in sentences. Across this and previous studies, multisensory training effects depended on the functional relationship between pathways engaged during training. Two principles are proposed to account for stimulus effects: (1) Stimuli presented to the trainee’s primary perceptual pathway will impede learning by a lower-rank pathway. (2) Stimuli presented to the trainee’s lower rank perceptual pathway will promote learning by a higher-rank pathway. The mechanisms supporting these principles are discussed in light of multisensory reverse hierarchy theory (RHT).

Evaluation of a cochlear-implant processing strategy incorporating phantom stimulation and asymmetric pulses

Objective: To evaluate a speech-processing strategy in which the lowest frequency channel is conveyed using an asymmetric pulse shape and “phantom stimulation”, where current is injected into one intra-cochlear electrode and where the return current is shared between an intra-cochlear and an extra-cochlear electrode. This strategy is expected to provide more selective excitation of the cochlear apex, compared to a standard strategy where the lowest-frequency channel is conveyed by symmetric pulses in monopolar mode. In both strategies all other channels were conveyed by monopolar stimulation. Design: Within-subjects comparison between the two strategies. Four experiments: (1) discrimination between the strategies, controlling for loudness differences, (2) consonant identification, (3) recognition of lowpass-filtered sentences in quiet, (4) sentence recognition in the presence of a competing speaker. Study sample: Eight users of the Advanced Bionics CII/Hi-Res 90k cochlear implant. Results: Listeners could easily discriminate between the two strategies but no consistent differences in performance were observed. Conclusions: The proposed method does not improve speech perception, at least in the short term.