Perceptual dissimilarities among acoustic stimuli and ipsilateral electric stimuli

Five users of cochlear implants who had residual acoustic hearing in the implanted ear postoperatively participated in a study comparing the percepts elicited by acoustic and electric stimuli. The stimuli comprised pulse trains delivered to single electrodes and pure tones presented ipsilaterally. In the experiments, 12 equally loud stimuli with differing frequencies, electrode positions, and pulse rates were generated. Subjects listened to all of the possible pairs of stimuli in each set, and provided a relative dissimilarity rating for the members of each stimulus pair. The data were analyzed using non-metric multi-dimensional scaling techniques. Stimulus spaces were plotted in two dimensions to represent the results for each subject with each stimulus set. The results suggested that one dimension was associated with a pitch-like percept, related to the acoustic tone frequency and the active electrode position. The second dimension separated the acoustic stimuli from the electric stimuli. Generally, the electric pulse rate seemed to have a relatively small perceptual effect in this experimental context. Overall, the results show that acoustic pure tones are perceived as very different from electric pulse trains delivered to single electrode positions with constant rate, even when both the acoustic and the electric stimuli are presented to the same ear.     

Motile responses of vestibular hair cells following caloric, electrical or chemical stimuli

Isolated, living vestibular hair cells (VHCs) from the guinea pig are capable of producing self-movements. Current injections and extracellular alternating current (a.c.) fields evoked mechanical responses of cell body or sensory hairs. Furthermore, superfusion in the presence of kainic acid or slow depolarizations by K-/gluconate evoked reversible slow motile responses of solitary vestibular sensory cells. If present in vivo, active VHC mechanics will influence the mechano-sensitive stereocilia and modulate stiffness and compliance of the receptor structure and its cupular or macular relationship. A tonic VHC motility might directly influence the displacement configuration in the cupula and macula organs and thus the micromechanical operating conditions of these sensory organs. Active mechanical events could contribute to adaptation processes (automatic gain control) and micromechanical non-linearities of stereociliary displacements. In addition, we demonstrate that direct caloric stimulation of isolated, living type I VHCs from guinea pig elicited mechanical responses of the sensory cells. This mechanism could contribute to the caloric induction of a nystagmus both under terrestrial and microgravitational conditions.     

Endoscopic management of Zenker's diverticulum: factors predictive of success or failure

OBJECTIVES: We review our experience with endoscopic management of Zenker's diverticulum. We sought to analyze and determine risk factors for success or failure of endoscopic diverticulum treatment. METHODS: We performed a retrospective review of 72 consecutive patients who underwent attempted endoscopic management of a Zenker's diverticulum between January 2000 and April 2006. The procedures were performed by either of 2 otolaryngologists. There were 50 men and 22 women ranging in age from 44 to 93 years. A total of 85 procedures were performed. The medical records were reviewed for preoperative diverticulum size (small, 1 to 2 cm; moderate, 2.1 to 3.0 cm; and large, more than 3.0 cm), intraoperative diverticulum characteristics, patient anatomic limitations that prevented adequate endoscopic visualization, surgical complications, and management of recurrences. RESULTS: Of our 72 patients, 61 (85%) were able to undergo endoscopic cricopharyngeal myotomy with diverticulum elimination. Of the 61 endoscopic procedures, 47 (77%) resulted in complete symptom resolution. The most common risk factors for recurrence were diverticulum size (more than 3 cm) and amount of redundant mucosa. Of the 14 patients with a recurrence, 10 (71%) underwent a repeat procedure. Six of the 14 (43%) had a successful excision via a cervical approach, and 4 of the 14 (29%) underwent a repeat endoscopic myotomy. There was 1 major complication (esophageal tear), and there were 3 minor complications (mucosal abrasions). CONCLUSIONS: Most patients with a Zenker's diverticulum are good candidates for endoscopic management. In our series, 84% of those who underwent endoscopic treatment ultimately achieved relief of symptoms. The patient morbidity is minimal. A large diverticulum with redundant mucosa is a risk factor for recurrence after endoscopic treatment.     

Auditory steady-state responses to multiple simultaneous stimuli in children with functional or sensorineural hearing loss

The goal of our study was to identify the role of auditory steady-state responses for hearing assessment in patients with functional hearing loss. The study design was to compare auditory steady-state response thresholds and standard pure-tone audiometry thresholds between patients with functional or sensorineural hearing loss. Subjects comprised 16 patients (24 ears) with functional hearing loss and 17 patients (24 ears) with sensorineural hearing loss. Differences and correlations between auditory steady-state response thresholds and standard pure-tone audiometry thresholds at 500, 1,000, 2,000 and 4,000 Hz were evaluated. In children with functional hearing loss, pure-tone audiometry thresholds and auditory steady-state response thresholds were significantly different at all frequencies and were not significantly correlated. In patients with sensorineural hearing loss, pure-tone audiometry thresholds and auditory steady-state response thresholds did not differ significantly at any frequencies and were significantly correlated. Auditory steady-state responses may have principal role in the assessment of auditory brainstem acuity, particularly at low frequencies in patients with functional hearing loss.     

Cervical vestibular evoked myogenic potentials via air conduction delivered by either sequentially or quasi-simultaneously presented narrow-band chirp stimuli

Objective: To produce sound-evoked cervical vestibular evoked myogenic potentials (cVEMPs). These are widely used for the diagnosis of peripheral vestibulopathies and disturbances of the sacculocollic reflexes. The main, sensitive, frequency for eliciting cVEMPs has been shown to be around 500?Hz.

Design: Narrow-band chirps in different frequency ranges (middle frequencies of 0.5, 1, 2 and 4?kHz) will be used for sequential and quasi-simultaneous stimulation of the cervical vestibular organ. As benchmarks, peak-to-peak p13 and n23 amplitudes were analysed.

Study samples: The pilot study used five normal-hearing subjects (mean age 38.6?years) none of whom have balance disorders.

Results: From 40 measurements, p13 and n23 could be identified in a total of 34 detected cVEMPs. As expected, amplitudes were highest at 500?Hz, followed by 1, 2 and 4?kHz. Using the quasi-simultaneous stimulation method led to a slight reduction in cVEMP amplitudes, but these remained in the same order according to magnitude: 0.5, 1, 2 and 4?kHz.

Conclusion: Sequential and quasi-simultaneous narrow-band chirps are effective for evoking cVEMPs. High amplitudes contribute to fast identification across an extended frequency range (0.5–4?kHz) and also contribute to a reduction in examination time and overall sound exposure.     

Long-term quality of life and its predictive factors after oncologic surgery and microvascular reconstruction in patients with oral or oropharyngeal cancer

The aims of this study were to evaluate long-term quality of life (QoL) and to determine its predictive factors after oncologic surgery and free flap reconstruction in patients with oral or oropharyngeal cancer. Patients treated at our institution between 2000 and 2009, who are alive and disease-free at least 1 year after therapy, completed the European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30 questionnaire and the specific H&N35 module. Eighty patients were included in our study. Global QoL score was 69.3 ± 22.7 %. Global QoL and general symptoms were correlated with T stage, whereas head and neck symptoms were correlated with T stage and tumor involvement of the tongue base. Emotional and social functioning scales, and resumption of professional activity were significantly associated with global QoL. In conclusion, T stage, tumor involvement of the tongue base, professional status and emotional and social functions were the main determinants of QoL in our study.     

Half-sine stimuli and wave I of the ABR

The relation between half-sine stimuli and wave I of the ABR was explored in this initial study. Electrical half-sines in both polarities at the nominal frequencies 1,000, 2,000, 4,000 and 8,000 Hz were fed through a TDH-39 phone into KEMAR, an acoustic maniken designed to reproduce the acoustic transformations of a representative pinna, ear canal and eardrum. The same electrical waveforms through the TDH phone (at a peak equivalent level of 90 dB SPL) were then used to elicit ABRs in 4 normal hearing young adult listeners. Comparisons between the acoustic waveforms and ABR wave I showed that (1) the initial condensation peaks were excitatory, and (2) wave I latency differences resulting from half-sines of the same frequency in opposite polarity appeared consistent with the timing differences between the initial condensation peaks of the opposed half-sines.     

Sound field audiometry: recommended stimuli and procedures

Comprehensive recommendations are presented for conducting sound field audiometry with frequency specific stimuli. These recommendations are primarily based on a series of investigations by the authors. The rationale for each recommendation is presented, together with a brief overview of the supporting research. The preferred stimuli are frequency modulation tones, triangularly or sinusoidally modulated at a rate of about 20 Hz, or suitably generated narrow bands of noise. The optimal bandwidths of the stimuli, expressed in percentages of the center frequency, vary with frequency. Stimuli suitable for most purposes have bandwidths ranging from about 30% at 0.25 kHz to about 10% at 4 kHz. Stimuli having narrower or broader bandwidths are desirable for some special purposes. The test room should be as nonreverberant as possible and the subject should be seated on an adjustable height chair with headrest. The control microphone method of calibration is preferred but a method is also presented for carrying out the traditional precalibration procedure. The SPL of the complex stimulus should be taken as the peak deflections on a sound level meter set to "RMS-FAST." A conversion table is presented which allows thresholds obtained in the sound field to be expressed as dB HTL. With the materials and methods described here it is possible to achieve the same reliability for sound field testing as for audiometry under earphones.     

Forward and backward masking with brief impulsive stimuli

The forward and backward masking effect of a 20-micros pulse was measured for delays ranging from 0 to -/+4 ms. Masking is not a monotonic function of delay in either forward or backward masking. For two of the three observers, the asymmetry in which forward masking exceeds that of backward masking is small for delays less than 500 micros. The implications of the data for the contribution of masking to the precedence effect are considered.     

Tinnitus suppression with threshold and subthreshold sound stimuli

In this preliminary report, we present the results from our investigation of 34 tinnitus patients for tinnitus suppression with frequency-specific sound stimuli within the auditory spectrum. Of this number, 22 (64.7%) experienced suppression, 5 (14.7%) had partial suppression, and 7 (20.6%) were nonresponders. Suppression of peripheral tinnitus may result when mechanosensitive outer hair cells are recruited by sound stimuli that can remain at subthreshold level. The suppression mechanism is possibly explained by the electromodel of the auditory system. This physiological model could be the basis of tinnitus suppression therapy in which a low-intensity, frequency-specific and tinnitus-suppressing sound stimulus is introduced instead of a wide-band masking noise.     

Response contingent stimuli and stuttering: issues and implications

The first papers concerning effects of response contingent stimuli (RCS) on stuttering and speech disfluency were published approximately 30 years ago. Research in this area fluorished until about 1980 after which relatively few studies have been reported. Reasons for the decline in interest are not altogether clear because crucial issues remain unresolved. This paper highlights and evaluates these issues and considers their implications for future research.     

Extratympanic electrocochleography: diagnostic and predictive value

OBJECTIVE: To define the clinical value of extratympanic electrocochleography (ECoG) in the diagnosis of Meniere's disease. STUDY DESIGN: Retrospective case review. SETTING: An otology/neurotology referral center. PATIENTS: A group of 252 patients with symptoms consistent with Meniere's disease and 20 normal-hearing control subjects. INTERVENTION: All patients underwent audiologic testing and extratympanic ECoG at the time of initial evaluation and, when possible, following treatment. MAIN OUTCOME MEASURES: Audiologic thresholds and summating and action potential ratios (SP:AP). RESULTS: Patients were classified into definite, probable, possible, and bilateral Meniere's disease groups according to American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) guidelines. The definite Meniere's group demonstrated an elevated SP:AP ratio in 74% of cases, the possible Meniere's group in 64%, and the bilateral group demonstrated elevated ratios in both ears in 66%. Contralateral ears produced elevated ratios in 42% for unilateral cases, whereas 40% of these ears reported at least one contralateral symptom. All 40 control ears were normal (SP:AP > or = 0.50). Results statistically correlated (p = 0.004) with the Meniere's staging system set forth in the 1995 AAO-HNS guidelines. No correlation was found between ECoG results and disease duration. Although 72% of the 86 follow-up patients reported complete or substantial vertigo control, changes from initial ECoG results did not specifically correlate to vertigo, tinnitus, or aural fullness improvement. CONCLUSIONS: Extratympanic ECoG can be useful in the diagnosis of Meniere's disease, lending promise to possible cases where objective audiologic data are lacking. Each testing center should study its own results to establish meaningful parameters and confidence levels.     

Temporal summation of repetitive click stimuli

Monaural loudness balances were performed by eight normal-hearing subjects to determine the effect of click repetition rate on loudness sensation. Click trains of 500 msec duration were matched in loudness to a standard 500 msec 1000 Hz tone burst presented at three reference loudness levels (70, 80, and 90 phons). Click trains were presented at repetition rates of 11, 31, 51, and 91 clicks per sec. It was found that click trains at faster repetition rates required lower intensities for judgments of equal loudness sensation. This finding was attributed to the process of temporal loudness summation. The magnitude and nature of the temporal summation process as well as the influence of the reference loudness level are discussed.     

Long-latency auditory evoked potentials with verbal and nonverbal stimuli

IntroductionLong-latency auditory evoked potentials represent the cortical activity related to attention, memory, and auditory discrimination skills. Acoustic signal processing occurs differently between verbal and nonverbal stimuli, influencing the latency and amplitude patterns.ObjectiveTo describe the latencies of the cortical potentials P1, N1, P2, N2, and P3, as well as P3 amplitude, with different speech stimuli and tone bursts, and to classify them in the presence and absence of these data.MethodsA total of 30 subjects with normal hearing were assessed, aged 18–32 years old, matched by gender. Nonverbal stimuli were used (tone burst; 1000 Hz – frequent and 4000 Hz – rare); and verbal (/ba/ – frequent; /ga/, /da/, and /di/ – rare).ResultsConsidering the component N2 for tone burst, the lowest latency found was 217.45 ms for the BA/DI stimulus; the highest latency found was 256.5 ms. For the P3 component, the shortest latency with tone burst stimuli was 298.7 with BA/GA stimuli, the highest, was 340 ms. For the P3 amplitude, there was no statistically significant difference among the different stimuli. For latencies of components P1, N1, P2, N2, P3, there were no statistical differences among them, regardless of the stimuli used.ConclusionThere was a difference in the latency of potentials N2 and P3 among the stimuli employed but no difference was observed for the P3 amplitude.     

Effects of noise on NST and NU 6 stimuli

This study determined how normal-hearing listeners' performance on a nonsense syllable test (NST) was affected by three noise competitors, and how these responses differed from those on the standard NU 6 meaningful word test. Twenty young adult listeners heard the stimuli via earphones and provided verbal responses to the NST and NU 6 items in competition with: white noise, multitalker noise, and white noise which was amplitude modulated by the multitalker noise, each at a 0 dB signal-to-noise ratio. Responses were scored on a whole-word (all-or-none) basis. Statistical analyses revealed that listeners' performance was always poorer on the NST than on the NU 6 regardless of competitor type; and that scores were better in the multitalker noise followed by white noise and amplitude modulated white noise. These data and those from earlier studies indicate that the NST is sufficiently difficult in quiet that it may not warrant testing in noise.     

Auditory unit responses to single-pulse and twin-pulse microwave stimuli

Responses of units in the cat cochlear nucleus to single microwave pulses with different durations and to twin microwave pulses with different interpulse delays are used to study microwave hearing. Inferred threshold specific absorption rate is less than 6 mW/g; inferred threshold specific absorption, less than 0.5 microJ/g. The existence of responses from units with characteristic frequencies (CFs) from 931 Hz to 25.5 kHz is not consistent with a primary role for head resonance in microwave hearing. Patterns of response amplitude have a periodicity of 1/CF and are fully explained by frequency content of the pulse stimulus and signal processing of the auditory system. For pulses shorter than about 0.24/CF, it is shown that response amplitude is predictably proportional to pulse energy.