Christopher W. Turner

University College London

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Bruce J. Gantz

University of Iowa

Kate Gfeller

University of Iowa

Lina A. J. Reiss

Oregon Health & Science University

Jacob Oleson

University of Iowa

Fan‐Gang Zeng

University of California, Irvine

Sue A. Karsten

University of Iowa

Gemma Learmonth

University of Stirling

Pamela E. Souza

Northwestern University

Amy R. Horwitz

Cleveland Clinic

Evan M. Relkin

Syracuse University

Cooperative Institutions

University of Iowa

Google (United States)

Cochlear (Australia)

University College London

National Hospital for Neurology and Neurosurgery

University College London Hospitals NHS Foundation Trust

Syracuse University

Cochlear (United States)

University of Glasgow

University of Iowa Hospitals and Clinics

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Contralateral stimulation and the masking overshoot effect

The Journal of the Acoustical Society of America (1994)

Christopher W. Turner Rebecca Waite Karolyn J. Cummings Melanie G. Rosen

Overshoot is the increase in masked threshold for a short signal presented at the onset of a masker compared to the threshold for a signal presented in the temporal center of the masker. One hypothesis to explain this effect is the slow onset time for masker-stimulated ipsilateral efferent activity to influence the response to the masked signal. Recent physiological experiments have shown that noise presented to the contralateral ear, which provides an increment in efferent activity, can increase the neural detectability of short tones masked by noise [Kawase etal., J. Neurophys. 70, 2533–2549 (1993)]. The present behavioral experiment took advantage of these findings and measured the amount of overshoot under conditions where a brief contralateral noise was presented prior to the masker onset, in an attempt to ‘‘prime’’ the efferent system prior to the masker onset. All measurements were conducted using insert earphones, which provide approximately 80 dB of interaural attenuation. The preceding contralateral noise reduced or eliminated the overshoot across a wide range of masker levels. Possible mechanisms for the overshoot effect will be discussed. [Work supported by NIDCD.]

Overshoot (microwave communication)

SIGNAL (programming language)

Absolute threshold

10.1121/1.411028

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Citations (0)

Spatial Dynamics of Microsaccades: Investigating the Influence of Fixational Proximity to Visual Stimuli on Saccade-Induced EEG Modulation

Journal of Vision (2024)

Christopher W. Turner Aleksandra Vučković Gemma Learmonth Alessio Fracasso

Microsaccade

Modulation (music)

Dynamics

10.1167/jov.24.10.607

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High-frequency audibility: Benefits for hearing-impaired listeners

The Journal of the Acoustical Society of America (1998)

Cynthia A. Hogan Christopher W. Turner

The present study was a systematic investigation of the benefit of providing hearing-impaired listeners with audible high-frequency speech information. Five normal-hearing and nine high-frequency hearing-impaired listeners identified nonsense syllables that were low-pass filtered at a number of cutoff frequencies. As a means of quantifying audibility for each condition, Articulation Index (AI) was calculated for each condition for each listener. Most hearing-impaired listeners demonstrated an improvement in speech recognition as additional audible high-frequency information was provided. In some cases for more severely impaired listeners, increasing the audibility of high-frequency speech information resulted in no further improvement in speech recognition, or even decreases in speech recognition. A new measure of how well hearing-impaired listeners used information within specific frequency bands called “efficiency” was devised. This measure compared the benefit of providing a given increase in speech audibility to a hearing-impaired listener to the benefit observed in normal-hearing listeners for the same increase in speech audibility. Efficiencies were calculated using the old AI method and the new AI method (which takes into account the effects of high speech presentation levels). There was a clear pattern in the results suggesting that as the degree of hearing loss at a given frequency increased beyond 55 dB HL, the efficacy of providing additional audibility to that frequency region was diminished, especially when this degree of hearing loss was present at frequencies of 4000 Hz and above. A comparison of analyses from the “old” and “new” AI procedures suggests that some, but not all, of the deficiencies of speech recognition in these listeners was due to high presentation levels.

Hearing impaired

Hearing aid

10.1121/1.423247

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Citations (317)

Cochlear implant users' spectral ripple resolution

The Journal of the Acoustical Society of America (2015)

Eun Kyung Jeon Christopher W. Turner Sue A. Karsten Belinda A. Henry Bruce J. Gantz

This study revisits the issue of the spectral ripple resolution abilities of cochlear implant (CI) users. The spectral ripple resolution of recently implanted CI recipients (implanted during the last 10 years) were compared to those of CI recipients implanted 15 to 20 years ago, as well as those of normal-hearing and hearing-impaired listeners from previously published data from Henry, Turner, and Behrens [J. Acoust. Soc. Am. 118, 1111–1121 (2005)]. More recently, implanted CI recipients showed significantly better spectral ripple resolution. There is no significant difference in spectral ripple resolution for these recently implanted subjects compared to hearing-impaired (acoustic) listeners. The more recently implanted CI users had significantly better pre-operative speech perception than previously reported CI users. These better pre-operative speech perception scores in CI users from the current study may be related to better performance on the spectral ripple discrimination task; however, other possible factors such as improvements in internal and external devices cannot be excluded.

Spectral resolution

Hearing impaired

Cochlear Implantation

10.1121/1.4932020

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Citations (32)

Acoustic plus Electric Speech Processing: Preliminary Results of a Multicenter Clinical Trial of the Iowa/Nucleus Hybrid Implant

Audiology and Neurotology (2006)

Bruce J. Gantz Christopher W. Turner Kate Gfeller

Aim: This communication details the latest preliminary results from an ongoing multicenter single-subject design clinical trial of the Iowa/Nucleus Hybrid 10-mm cochlear implant. Selection criteria, surgical strategies used for hearing preservation, and the benefits of preserved residual low-frequency hearing, improved word understanding in noise, and music appreciation are described. Patients and Methods: The device has been implanted in 48 individuals with residual low-frequency hearing. Results:Hearing preservation has been accomplished in 46/48 subjects. Acoustic speech perception has also been preserved. Combined acoustic plus electric speech processing has enabled most of this group of volunteers to gain improved word understanding as compared to their preoperative hearing with bilateral hearing aids. A subset of subjects with 12 months or more experience demonstrates CNC word understanding continues to improve more than 24 months after implantation. Improved word understanding in noise is also a benefit of acoustic plus electric speech processing. Conclusions:The improvement of speech in noise and melody recognition is linked to the ability to distinguish fine pitch differences as the result of preserved residual low-frequency acoustic hearing. Both of these measures are very important in real life to the hearing impaired. Preservation of residual low-frequency hearing should be considered when expanding candidate selection criteria for standard cochlear implants.

10.1159/000095616

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Citations (161)

Total Energy and Critical Intensity Concepts in Noise Damage

Annals of Otology Rhinology & Laryngology (1981)

W. Dixon Ward Arndt J. Duvall Peter A. Santi Christopher W. Turner

Groups of chinchillas were given a series of noise exposures of approximately equal energy ranging from 22 minutes at 120 dB SPL to 150 days at 82 dB. For all exposures involving levels of 112 dB or less, the same average permanent hearing losses (15–20 dB) and degree of outer hair cell destruction (8–10%) resulted, thus confirming the validity of the total energy principle for assessing the hazard associated with single continuous exposures at moderate levels. The 22-minute, 120-dB exposure, however, produced a 60-dB hearing loss and massive hair cell destruction (70–80%), indicating that some critical level had been exceeded, thus producing acoustic trauma. Further histological study suggests that the massive destruction is a result of breaks in the organ of Corti, produced by severe mechanical stress, that permit the mixture of endolymph with perilymph, thus creating a hostile environment for the hair cells.

Perilymph

Chinchilla

Acoustic trauma

Total energy

Endolymph

10.1177/000348948109000615

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Citations (39)

Just noticeable differences for intensity and their relation to loudness

The Journal of the Acoustical Society of America (1993)

Jennifer H. Johnson Christopher W. Turner Jozef J. Zwislocki Robert H. Margolis

The present study examines the relation between the form of the loudness function and the size of the intensity just noticeable difference (jnd). The hypothesis that equal loudnesses at any given sound frequency yield equal-intensity jnd’s was examined. In addition, Hellman et al.’s [J. Acoust. Soc. Am. 82, 448–453 (1987)] experiment, which showed that jnd’s are independent of the slope of the loudness function was replicated. Threshold shifts and altered loudness-balance functions for 1-kHz tones were produced by using backgrounds of narrow- or wideband noise. The two types of background noise produced intersecting points on loudness-balance functions at which intensity jnd’s were obtained. Intensity jnd’s were also obtained at equal-loudness levels (corresponding to 30, 40, 50, and 60 dB SL in the unmasked ear) under each of the two noise conditions and in quiet. The results indicate that tones of equal loudness produce approximately equal jnd’s and that there is no apparent relation between the slope of the loudness-balance functions and the size of the intensity jnd.

Intensity

10.1121/1.405404

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Citations (29)

Binaural Loudness Matches in Unilaterally Impaired Listeners

The Quarterly Journal of Experimental Psychology Section A (1991)

Fan‐Gang Zeng Christopher W. Turner

Binaural loudness matching data using a 2IFC adaptive procedure were obtained in high-frequency, unilateral cochlear-impaired listeners. The matches were obtained at frequencies where both ears had similarly normal thresholds, and also at other frequencies where the impaired ear had various degrees of hearing loss. In these listeners, one presumed difference between the ears is the limited or altered spread of excitation in the impaired ear. In agreement with previous studies using other approaches (Hellman, 1974, 1978; Hellman & Meiselman, 1986; Moore, Glasberg, Hess & Birchall, 1985; Schneider & Parker, 1987), the results of the present study suggest that both the range and the slope of loudness growth function are not dependent on the spread of excitation, but instead are related primarily to the degree of threshold elevation at the test frequency. Following this suggestion, a spread-of-excitation-independent model, based upon a group of neurons with the same characteristic frequency (CF) but different thresholds, is proposed to account for loudness growth in both normal and recruitment cases. In particular, it is shown quantitatively that a compressed distribution of thresholds due to threshold elevation may be responsible for loudness recruitment in sensorineural hearing loss.

Psychoacoustics

10.1080/14640749108400987

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Citations (43)

Input/output amplitude transfer function for median nerve somatosensory evoked potentials

Electroencephalography and Clinical Neurophysiology (1990)

Ronald G. Emerson Paul C. Stanton Christopher W. Turner

Somatosensory evoked potential

10.1016/0013-4694(90)91862-j

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Intensity discrimination determined with two paradigms in normal and hearing-impaired subjects

The Journal of the Acoustical Society of America (1989)

Christopher W. Turner Jozef J. Zwislocki Paul R. Filion

The literature on auditory intensity jnd’s is ambiguous with respect to the relationship between the jnd’s measured with gated and continuous pedestals and with respect to changes in this relationship in the presence of loudness recruitment accompanying cochlear pathology. In an attempt to clarify these issues and to lay a foundation for systematic investigations of the dependence on the jnd’s on loudness functions, the jnd’s for pure tones with gated- and continuous-pedestal paradigms of two groups of subjects, one with normal hearing and one with hearing loss of cochlear origin, were measured. The experiments were performed at 0.5, 2, and 6 kHz, and at a wide range of sensation levels (SLs) by means of an adaptive two-alternative, forced-choice (2IFC) procedure. The jnd’s obtained with the continuous-pedestal method were smaller than those obtained with the gated-pedestal method for both groups of subjects. They also had smaller intersubject standard deviations. When jnd’s of the two groups were compared on the basis of equal SLs, the group with hearing loss showed smaller jnd values than the group with normal hearing for both pedestal paradigms. When the comparisons were made on the basis of equal sound-pressure levels (SPLs), both groups showed similar values for moderate and high SPLs. At relatively low SPLs, the group with hearing loss tended to have somewhat higher values.

Pedestal

Intensity

Just-noticeable difference

10.1121/1.398329

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Citations (33)