1
|
Navntoft CA, Landsberger DM, Barkat TR, Marozeau J. The Perception of Ramped Pulse Shapes in Cochlear Implant Users. Trends Hear 2021; 25:23312165211061116. [PMID: 34935552 PMCID: PMC8724057 DOI: 10.1177/23312165211061116] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The electric stimulation provided by current cochlear implants (CI) is not power
efficient. One underlying problem is the poor efficiency by which information
from electric pulses is transformed into auditory nerve responses. A novel
stimulation paradigm using ramped pulse shapes has recently been proposed to
remedy this inefficiency. The primary motivation is a better biophysical fit to
spiral ganglion neurons with ramped pulses compared to the rectangular pulses
used in most contemporary CIs. Here, we tested the hypotheses that ramped pulses
provide more efficient stimulation compared to rectangular pulses and that a
rising ramp is more efficient than a declining ramp. Rectangular, rising ramped
and declining ramped pulse shapes were compared in terms of charge efficiency
and discriminability, and threshold variability in seven CI listeners. The tasks
included single-channel threshold detection, loudness-balancing, discrimination
of pulse shapes, and threshold measurement across the electrode array. Results
showed that reduced charge, but increased peak current amplitudes, was required
at threshold and most comfortable levels with ramped pulses relative to
rectangular pulses. Furthermore, only one subject could reliably discriminate
between equally-loud ramped and rectangular pulses, suggesting variations in
neural activation patterns between pulse shapes in that participant. No
significant difference was found between rising and declining ramped pulses
across all tests. In summary, the present findings show some benefits of charge
efficiency with ramped pulses relative to rectangular pulses, that the direction
of a ramped slope is of less importance, and that most participants could not
perceive a difference between pulse shapes.
Collapse
Affiliation(s)
- Charlotte Amalie Navntoft
- Hearing Systems Group, Department of Health Technology, 5205Technical University of Denmark, Kgs. Lyngby, Denmark.,Brain and Sound Lab, Department of Biomedicine, 27209Basel University, Basel, Switzerland
| | - David M Landsberger
- Department of Otolaryngology, 12296New York University School of Medicine, New York, USA
| | - Tania Rinaldi Barkat
- Brain and Sound Lab, Department of Biomedicine, 27209Basel University, Basel, Switzerland
| | - Jeremy Marozeau
- Hearing Systems Group, Department of Health Technology, 5205Technical University of Denmark, Kgs. Lyngby, Denmark
| |
Collapse
|
2
|
Adaptation to pitch-altered feedback is independent of one's own voice pitch sensitivity. Sci Rep 2020; 10:16860. [PMID: 33033324 PMCID: PMC7544828 DOI: 10.1038/s41598-020-73932-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 09/23/2020] [Indexed: 01/17/2023] Open
Abstract
Monitoring voice pitch is a fine-tuned process in daily conversations as conveying accurately the linguistic and affective cues in a given utterance depends on the precise control of phonation and intonation. This monitoring is thought to depend on whether the error is treated as self-generated or externally-generated, resulting in either a correction or inflation of errors. The present study reports on two separate paradigms of adaptation to altered feedback to explore whether participants could behave in a more cohesive manner once the error is of comparable size perceptually. The vocal behavior of normal-hearing and fluent speakers was recorded in response to a personalized size of pitch shift versus a non-specific size, one semitone. The personalized size of shift was determined based on the just-noticeable difference in fundamental frequency (F0) of each participant’s voice. Here we show that both tasks successfully demonstrated opposing responses to a constant and predictable F0 perturbation (on from the production onset) but these effects barely carried over once the feedback was back to normal, depicting a pattern that bears some resemblance to compensatory responses. Experiencing a F0 shift that is perceived as self-generated (because it was precisely just-noticeable) is not enough to force speakers to behave more consistently and more homogeneously in an opposing manner. On the contrary, our results suggest that the type of the response as well as the magnitude of the response do not depend in any trivial way on the sensitivity of participants to their own voice pitch. Based on this finding, we speculate that error correction could possibly occur even with a bionic ear, typically even when F0 cues are too subtle for cochlear implant users to detect accurately.
Collapse
|
3
|
Jorgensen EJ, McCreery RW, Kirby BJ, Brennan M. Effect of level on spectral-ripple detection threshold for listeners with normal hearing and hearing loss. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2020; 148:908. [PMID: 32873021 PMCID: PMC7443170 DOI: 10.1121/10.0001706] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 07/07/2020] [Accepted: 07/20/2020] [Indexed: 06/11/2023]
Abstract
This study investigated the effect of presentation level on spectral-ripple detection for listeners with and without sensorineural hearing loss (SNHL). Participants were 25 listeners with normal hearing and 25 listeners with SNHL. Spectral-ripple detection thresholds (SRDTs) were estimated at three spectral densities (0.5, 2, and 4 ripples per octave, RPO) and three to four sensation levels (SLs) (10, 20, 40, and, when possible, 60 dB SL). Each participant was also tested at 90 dB sound pressure level (SPL). Results indicate that level affected SRDTs. However, the effect of level depended on ripple density and hearing status. For all listeners and all RPO conditions, SRDTs improved from 10 to 40 dB SL. In the 2- and 4-RPO conditions, SRDTs became poorer from the 40 dB SL to the 90 dB SPL condition. The results suggest that audibility likely controls spectral-ripple detection at low SLs for all ripple densities, whereas spectral resolution likely controls spectral-ripple detection at high SLs and ripple densities. For optimal ripple detection across all listeners, clinicians and researchers should use a SL of 40 dB SL. To avoid absolute-level confounds, a presentation level of 80 dB SPL can also be used.
Collapse
Affiliation(s)
- Erik J Jorgensen
- Department of Communication Sciences and Disorders, University of Iowa, Iowa City, Iowa 52242, USA
| | - Ryan W McCreery
- Boys Town National Research Hospital, Omaha, Nebraska 68124, USA
| | - Benjamin J Kirby
- Department of Audiology and Speech-Language Pathology, University of North Texas, Denton, Texas 76203, USA
| | - Marc Brennan
- Department of Special Education and Communication Disorders, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA
| |
Collapse
|
4
|
McKay CM, Rickard N, Henshall K. Intensity Discrimination and Speech Recognition of Cochlear Implant Users. J Assoc Res Otolaryngol 2018; 19:589-600. [PMID: 29777327 DOI: 10.1007/s10162-018-0675-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 05/07/2018] [Indexed: 12/23/2022] Open
Abstract
The relation between speech recognition and within-channel or across-channel (i.e., spectral tilt) intensity discrimination was measured in nine CI users (11 ears). Within-channel intensity difference limens (IDLs) were measured at four electrode locations across the electrode array. Spectral tilt difference limens were measured with (XIDL-J) and without (XIDL) level jitter. Only three subjects could perform the XIDL-J task with the amount of jitter required to limit use of within-channel cues. XIDLs (normalized to %DR) were correlated with speech recognition (r = 0.67, P = 0.019) and were highly correlated with IDLs. XIDLs were on average nearly 3 times larger than IDLs and did not vary consistently with the spatial separation of the two component electrodes. The overall pattern of results was consistent with a common underlying subject-dependent limitation in the two difference limen tasks, hypothesized to be perceptual variance (how the perception of a sound differs on different presentations), which may also underlie the correlation of XIDLs with speech recognition. Evidence that spectral tilt discrimination is more important for speech recognition than within-channel intensity discrimination was not unequivocally shown in this study. However, the results tended to support this proposition, with XIDLs more correlated with speech performance than IDLs, and the ratio XIDL/IDL also being correlated with speech recognition. If supported by further research, the importance of perceptual variance as a limiting factor in speech understanding for CI users has important implications for efforts to improve outcomes for those with poor speech recognition.
Collapse
Affiliation(s)
- Colette M McKay
- Bionics Institute, 384-388 Albert St, East Melbourne, 3002, Australia. .,Department of Medical Bionics, The University of Melbourne, Melbourne, Australia.
| | - Natalie Rickard
- Bionics Institute, 384-388 Albert St, East Melbourne, 3002, Australia
| | | |
Collapse
|
5
|
Brochier T, McKay C, McDermott H. Rate modulation detection thresholds for cochlear implant users. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2018; 143:1214. [PMID: 29495682 DOI: 10.1121/1.5025048] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The perception of temporal amplitude modulations is critical for speech understanding by cochlear implant (CI) users. The present study compared the ability of CI users to detect sinusoidal modulations of the electrical stimulation rate and current level, at different presentation levels (80% and 40% of the dynamic range) and modulation frequencies (10 and 100 Hz). Rate modulation detection thresholds (RMDTs) and amplitude modulation detection thresholds (AMDTs) were measured and compared to assess whether there was a perceptual advantage to either modulation method. Both RMDTs and AMDTs improved with increasing presentation level and decreasing modulation frequency. RMDTs and AMDTs were correlated, indicating that a common processing mechanism may underlie the perception of rate modulation and amplitude modulation, or that some subject-dependent factors affect both types of modulation detection.
Collapse
Affiliation(s)
- Tim Brochier
- Department of Medical Bionics, University of Melbourne, 384-388 Albert Street, East Melbourne, Victoria 3002, Australia
| | - Colette McKay
- The Bionics Institute, 384-388 Albert Street, East Melbourne, Victoria 3002, Australia
| | - Hugh McDermott
- The Bionics Institute, 384-388 Albert Street, East Melbourne, Victoria 3002, Australia
| |
Collapse
|
6
|
Brochier T, McDermott HJ, McKay CM. The effect of presentation level and stimulation rate on speech perception and modulation detection for cochlear implant users. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2017; 141:4097. [PMID: 28618807 PMCID: PMC5457292 DOI: 10.1121/1.4983658] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 04/26/2017] [Accepted: 05/03/2017] [Indexed: 06/07/2023]
Abstract
In order to improve speech understanding for cochlear implant users, it is important to maximize the transmission of temporal information. The combined effects of stimulation rate and presentation level on temporal information transfer and speech understanding remain unclear. The present study systematically varied presentation level (60, 50, and 40 dBA) and stimulation rate [500 and 2400 pulses per second per electrode (pps)] in order to observe how the effect of rate on speech understanding changes for different presentation levels. Speech recognition in quiet and noise, and acoustic amplitude modulation detection thresholds (AMDTs) were measured with acoustic stimuli presented to speech processors via direct audio input (DAI). With the 500 pps processor, results showed significantly better performance for consonant-vowel nucleus-consonant words in quiet, and a reduced effect of noise on sentence recognition. However, no rate or level effect was found for AMDTs, perhaps partly because of amplitude compression in the sound processor. AMDTs were found to be strongly correlated with the effect of noise on sentence perception at low levels. These results indicate that AMDTs, at least when measured with the CP910 Freedom speech processor via DAI, explain between-subject variance of speech understanding, but do not explain within-subject variance for different rates and levels.
Collapse
Affiliation(s)
- Tim Brochier
- Department of Medical Bionics, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Hugh J McDermott
- The Bionics Institute, 384-388 Albert Street, East Melbourne, Victoria 3002, Australia
| | - Colette M McKay
- The Bionics Institute, 384-388 Albert Street, East Melbourne, Victoria 3002, Australia
| |
Collapse
|
7
|
Debruyne JA, Francart T, Janssen AML, Douma K, Brokx JPL. Fitting prelingually deafened adult cochlear implant users based on electrode discrimination performance. Int J Audiol 2016; 56:174-185. [PMID: 27758152 DOI: 10.1080/14992027.2016.1243262] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
OBJECTIVE This study investigated the hypotheses that (1) prelingually deafened CI users do not have perfect electrode discrimination ability and (2) the deactivation of non-discriminable electrodes can improve auditory performance. DESIGN Electrode discrimination difference limens were determined for all electrodes of the array. The subjects' basic map was subsequently compared to an experimental map, which contained only discriminable electrodes, with respect to speech understanding in quiet and in noise, listening effort, spectral ripple discrimination and subjective appreciation. STUDY SAMPLE Subjects were six prelingually deafened, late implanted adults using the Nucleus cochlear implant. RESULTS Electrode discrimination difference limens across all subjects and electrodes ranged from 0.5 to 7.125, with significantly larger limens for basal electrodes. No significant differences were found between the basic map and the experimental map on auditory tests. Subjective appreciation was found to be significantly poorer for the experimental map. CONCLUSIONS Prelingually deafened CI users were unable to discriminate between all adjacent electrodes. There was no difference in auditory performance between the basic and experimental map. Potential factors contributing to the absence of improvement with the experimental map include the reduced number of maxima, incomplete adaptation to the new frequency allocation, and the mainly basal location of deactivated electrodes.
Collapse
Affiliation(s)
- Joke A Debruyne
- a Department of Otorhinolaryngology, Head and Neck Surgery , Maastricht University Medical Center , Maastricht , The Netherlands.,b School for Mental Health and Neuroscience, Maastricht University , Maastricht, The Netherlands
| | - Tom Francart
- c Leuven Department of Neurosciences , KU , ExpORL , Belgium
| | - A Miranda L Janssen
- a Department of Otorhinolaryngology, Head and Neck Surgery , Maastricht University Medical Center , Maastricht , The Netherlands.,d School for Public Health and Primary Care (CAPHRI) , Department of Methodology and Statistics , Maastricht University , Maastricht , The Netherlands , and
| | - Kim Douma
- a Department of Otorhinolaryngology, Head and Neck Surgery , Maastricht University Medical Center , Maastricht , The Netherlands.,e Adelante , Center of Expertise in Rehabilitation and Audiology , Hoensbroek , The Netherlands
| | - Jan P L Brokx
- a Department of Otorhinolaryngology, Head and Neck Surgery , Maastricht University Medical Center , Maastricht , The Netherlands.,b School for Mental Health and Neuroscience, Maastricht University , Maastricht, The Netherlands
| |
Collapse
|
8
|
Perceptual interactions between electrodes using focused and monopolar cochlear stimulation. J Assoc Res Otolaryngol 2015; 16:401-12. [PMID: 25742726 DOI: 10.1007/s10162-015-0511-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 02/13/2015] [Indexed: 01/06/2023] Open
Abstract
In today's cochlear implant (CI) systems, the monopolar (MP) electrode configuration is the most commonly used stimulation mode, requiring only a single current source. However, with an implant that will allow simultaneous activation of multiple independent current sources, it is possible to implement an all-polar (AP) stimulation mode designed to create a focused electrical field. The goal of this experiment was to study the potential benefits of this all-polar mode for reducing uncontrolled electrode interactions compared with the monopolar mode. The five participants who took part in the study were implanted with a research device that was connected via a percutaneous connector to a benchtop stimulator providing 22 independent current sources. The perceptual effects of the AP mode were tested in three experiments. In Experiment 1, the current level difference between loudness-matched sequential and simultaneous stimuli composed of 2 spatially separated pulse trains was measured as function of the electrode separation. Results indicated a strong current-summation interaction for simultaneous stimuli in the MP mode for separations up to at least 4.8 mm. No significant interaction was found in the AP mode beyond a separation of 2.4 mm. In Experiment 2, a forward-masking paradigm was used with fixed equally loud probes in AP and MP modes, and AP maskers presented on different electrode positions. Results indicated a similar spatial masking pattern between modes. In Experiment 3, subjects were asked to discriminate between across-electrode temporal delays. It was hypothesized that discrimination would decrease with electrode separation faster in AP compared to MP modes. However, results showed no difference between the two modes. Overall, the results indicated that the AP mode produced less current spread than MP mode but did not lead to a significant advantage in terms of spread of neuronal excitation at equally loud levels.
Collapse
|
9
|
A general formula for computing maximum proportion correct scores in various psychophysical paradigms with arbitrary probability distributions of stimulus observations. Atten Percept Psychophys 2015; 77:1448-60. [PMID: 25724517 DOI: 10.3758/s13414-015-0838-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Proportion correct (Pc) is a fundamental measure of task performance in psychophysics. The maximum Pc score that can be achieved by an optimal (maximum-likelihood) observer in a given task is of both theoretical and practical importance, because it sets an upper limit on human performance. Within the framework of signal detection theory, analytical solutions for computing the maximum Pc score have been established for several common experimental paradigms under the assumption of Gaussian additive internal noise. However, as the scope of applications of psychophysical signal detection theory expands, the need is growing for psychophysicists to compute maximum Pc scores for situations involving non-Gaussian (internal or stimulus-induced) noise. In this article, we provide a general formula for computing the maximum Pc in various psychophysical experimental paradigms for arbitrary probability distributions of sensory activity. Moreover, easy-to-use MATLAB code implementing the formula is provided. Practical applications of the formula are illustrated, and its accuracy is evaluated, for two paradigms and two types of probability distributions (uniform and Gaussian). The results demonstrate that Pc scores computed using the formula remain accurate even for continuous probability distributions, as long as the conversion from continuous probability density functions to discrete probability mass functions is supported by a sufficiently high sampling resolution. We hope that the exposition in this article, and the freely available MATLAB code, facilitates calculations of maximum performance for a wider range of experimental situations, as well as explorations of the impact of different assumptions concerning internal-noise distributions on maximum performance in psychophysical experiments.
Collapse
|
10
|
Galvin JJ, Fu QJ, Oba S, Başkent D. A method to dynamically control unwanted loudness cues when measuring amplitude modulation detection in cochlear implant users. J Neurosci Methods 2013; 222:207-12. [PMID: 24269251 DOI: 10.1016/j.jneumeth.2013.10.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 10/23/2013] [Accepted: 10/26/2013] [Indexed: 10/26/2022]
Abstract
BACKGROUND Amplitude modulation (AM) detection is a measure of temporal processing that has been correlated with cochlear implant (CI) users' speech understanding. For CI users, AM stimuli have been shown to be louder than steady-state (non-AM) stimuli presented at the same reference current level, suggesting that unwanted loudness cues might contribute to CI users' AM sensitivity as measured in a modulation detection task. In this paper, a new method is introduced to dynamically control unwanted AM loudness cues when adaptively measuring modulation detection thresholds (MDTs) in CI users. METHODS MDTs were adaptively measured in 9 CI subjects using a three-alternative, forced-choice procedure, with and without dynamic control of unwanted AM loudness cues. To control for AM loudness cues during the MDT task, the level of the steady-state (non-AM) stimuli was increased to match the loudness of the AM stimulus using a non-linear amplitude scaling function, which was obtained by first loudness-balancing non-AM stimuli to AM stimuli at various modulation depths. To further protect against unwanted loudness cues, ±0.75dB of level roving was also applied to all stimuli during the MDT task. RESULTS Absolute MDTs were generally poorer when unwanted AM loudness cues were controlled. However, the effects of modulation frequency and presentation level on modulation sensitivity were fundamentally unchanged by the availability of AM loudness cues. CONCLUSIONS The data suggest that the present method controlling for unwanted AM loudness cues might better represent CI users' MDTs, without changing fundamental effects of modulation frequency and presentation level on CI users' modulation sensitivity.
Collapse
Affiliation(s)
- John J Galvin
- Division of Communication and Auditory Neuroscience, House Research Institute, Los Angeles, CA, USA; University of California Los Angeles, David Geffen School of Medicine Department of Head and Neck Surgery, Los Angeles, CA, USA; Department of Otorhinolaryngology, Head and Neck Surgery, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands; Research School of Behavioral and Cognitive Neurosciences, Graduate School of Medical Sciences, University of Groningen, Groningen, The Netherlands.
| | - Qian-Jie Fu
- Division of Communication and Auditory Neuroscience, House Research Institute, Los Angeles, CA, USA; University of California Los Angeles, David Geffen School of Medicine Department of Head and Neck Surgery, Los Angeles, CA, USA
| | - Sandy Oba
- Division of Communication and Auditory Neuroscience, House Research Institute, Los Angeles, CA, USA; University of California Los Angeles, David Geffen School of Medicine Department of Head and Neck Surgery, Los Angeles, CA, USA
| | - Deniz Başkent
- Department of Otorhinolaryngology, Head and Neck Surgery, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands; Research School of Behavioral and Cognitive Neurosciences, Graduate School of Medical Sciences, University of Groningen, Groningen, The Netherlands
| |
Collapse
|
11
|
Dai H, Micheyl C. Separating the contributions of primary and unwanted cues in psychophysical studies. Psychol Rev 2012; 119:770-88. [PMID: 22844984 DOI: 10.1037/a0029343] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A fundamental issue in the design and the interpretation of experimental studies of perception relates to the question of whether the participants in these experiments could perform the perceptual task assigned to them using another feature, or cue, than that intended by the experimenter. An approach frequently used by auditory- and visual-perception researchers to guard against this possibility involves applying random variations to the stimuli across presentations or trials so as to make the "unwanted" cue unreliable for the participants. However, the theoretical basis of this widespread practice is not well developed. In this article, we describe a 2-channel model based on general principles of psychophysical signal detection theory, which can be used to assess the respective contributions of the unwanted cue and of the primary cue to performance or thresholds measured in perceptual discrimination experiments involving stimulus randomization. Example applications of the model to the analysis of results obtained in representative studies from the auditory- and visual-perception literature are provided. In several cases, the results of the model-based analyses indicate that the effectiveness of the randomization procedure was less than originally assumed by the authors of these studies. These findings underscore the importance of quantifying the potential influence of unwanted cues on the results of psychophysical experiments, even when stimulus randomization is used.
Collapse
Affiliation(s)
- Huanping Dai
- Dai, Department of Speech, Language, and Hearing Sciences,University of Arizona, Tucson, AZ 85721, USA.
| | | |
Collapse
|
12
|
Fraser M, McKay CM. Temporal modulation transfer functions in cochlear implantees using a method that limits overall loudness cues. Hear Res 2011; 283:59-69. [PMID: 22146425 PMCID: PMC3314947 DOI: 10.1016/j.heares.2011.11.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 11/07/2011] [Accepted: 11/22/2011] [Indexed: 11/29/2022]
Abstract
Temporal modulation transfer functions (TMTFs) were measured for six users of cochlear implants, using different carrier rates and levels. Unlike most previous studies investigating modulation detection, the experimental design limited potential effects of overall loudness cues. Psychometric functions (percent correct discrimination of modulated from unmodulated stimuli versus modulation depth) were obtained. For each modulation depth, each modulated stimulus was loudness balanced to the unmodulated reference stimulus, and level jitter was applied in the discrimination task. The loudness-balance data showed that the modulated stimuli were louder than the unmodulated reference stimuli with the same average current, thus confirming the need to limit loudness cues when measuring modulation detection. TMTFs measured in this way had a low-pass characteristic, with a cut-off frequency (at comfortably loud levels) similar to that for normal-hearing listeners. A reduction in level caused degradation in modulation detection efficiency and a lower-cut-off frequency (i.e. poorer temporal resolution). An increase in carrier rate also led to a degradation in modulation detection efficiency, but only at lower levels or higher modulation frequencies. When detection thresholds were expressed as a proportion of dynamic range, there was no effect of carrier rate for the lowest modulation frequency (50 Hz) at either level.
Collapse
Affiliation(s)
- Matthew Fraser
- School of Psychological Sciences, The University of Manchester, Manchester M13 9PL, UK
| | | |
Collapse
|
13
|
Won JH, Jones GL, Drennan WR, Jameyson EM, Rubinstein JT. Evidence of across-channel processing for spectral-ripple discrimination in cochlear implant listeners. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2011; 130:2088-97. [PMID: 21973363 PMCID: PMC3206911 DOI: 10.1121/1.3624820] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Spectral-ripple discrimination has been used widely for psychoacoustical studies in normal-hearing, hearing-impaired, and cochlear implant listeners. The present study investigated the perceptual mechanism for spectral-ripple discrimination in cochlear implant listeners. The main goal of this study was to determine whether cochlear implant listeners use a local intensity cue or global spectral shape for spectral-ripple discrimination. The effect of electrode separation on spectral-ripple discrimination was also evaluated. Results showed that it is highly unlikely that cochlear implant listeners depend on a local intensity cue for spectral-ripple discrimination. A phenomenological model of spectral-ripple discrimination, as an "ideal observer," showed that a perceptual mechanism based on discrimination of a single intensity difference cannot account for performance of cochlear implant listeners. Spectral modulation depth and electrode separation were found to significantly affect spectral-ripple discrimination. The evidence supports the hypothesis that spectral-ripple discrimination involves integrating information from multiple channels.
Collapse
Affiliation(s)
- Jong Ho Won
- Virginia Merrill Bloedel Hearing Research Center, Department of Otolaryngology-Head and Neck Surgery, University of Washington, Seattle, Washington 98195, USA.
| | | | | | | | | |
Collapse
|
14
|
Borchert EMO, Micheyl C, Oxenham AJ. Perceptual grouping affects pitch judgments across time and frequency. J Exp Psychol Hum Percept Perform 2011; 37:257-69. [PMID: 21077719 PMCID: PMC3057773 DOI: 10.1037/a0020670] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Pitch, the perceptual correlate of fundamental frequency (F0), plays an important role in speech, music, and animal vocalizations. Changes in F0 over time help define musical melodies and speech prosody, while comparisons of simultaneous F0 are important for musical harmony, and for segregating competing sound sources. This study compared listeners' ability to detect differences in F0 between pairs of sequential or simultaneous tones that were filtered into separate, nonoverlapping spectral regions. The timbre differences induced by filtering led to poor F0 discrimination in the sequential, but not the simultaneous, conditions. Temporal overlap of the two tones was not sufficient to produce good performance; instead performance appeared to depend on the two tones being integrated into the same perceptual object. The results confirm the difficulty of comparing the pitches of sequential sounds with different timbres and suggest that, for simultaneous sounds, pitch differences may be detected through a decrease in perceptual fusion rather than an explicit coding and comparison of the underlying F0s.
Collapse
Affiliation(s)
- Elizabeth M O Borchert
- Auditory Perception and Cognition Laboratory, Department of Psychology, Uiversity of Minnesota, Twin Cities, MN, USA.
| | | | | |
Collapse
|
15
|
McDermott JH, Keebler MV, Micheyl C, Oxenham AJ. Musical intervals and relative pitch: frequency resolution, not interval resolution, is special. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2010; 128:1943-1951. [PMID: 20968366 PMCID: PMC2981111 DOI: 10.1121/1.3478785] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Revised: 07/16/2010] [Accepted: 07/19/2010] [Indexed: 05/26/2023]
Abstract
Pitch intervals are central to most musical systems, which utilize pitch at the expense of other acoustic dimensions. It seemed plausible that pitch might uniquely permit precise perception of the interval separating two sounds, as this could help explain its importance in music. To explore this notion, a simple discrimination task was used to measure the precision of interval perception for the auditory dimensions of pitch, brightness, and loudness. Interval thresholds were then expressed in units of just-noticeable differences for each dimension, to enable comparison across dimensions. Contrary to expectation, when expressed in these common units, interval acuity was actually worse for pitch than for loudness or brightness. This likely indicates that the perceptual dimension of pitch is unusual not for interval perception per se, but rather for the basic frequency resolution it supports. The ubiquity of pitch in music may be due in part to this fine-grained basic resolution.
Collapse
Affiliation(s)
- Josh H McDermott
- Center for Neural Science, New York University, 4 Washington Place, New York, New York 10003, USA.
| | | | | | | |
Collapse
|