Rate pitch discrimination in cochlear implant users with the use of double pulses and different interpulse intervals

The rate pitch discrimination ability of cochlear implant (CI) users is poor compared to normal-hearing (NH) listeners. At low pulse rates, the just noticeable difference (JND) is on average 20% of the base rate, while NH listeners can discriminate small frequency differences of 0.2% at 1?kHz. Recent investigations suggest that double pulses with short interpulse intervals (IPIs) may have a beneficial effect on rate pitch discrimination in CI users. In a first experiment psychophysical tests were carried out to establish whether rate pitch in CI users could be improved by applying double pulses with equal amplitude and short IPIs. Pulse trains with base rates of 200 and 400?pps, composed of either single pulses or double pulses with IPIs of 15, 50, and 150?μs were presented. In a second experiment pairwise comparisons were carried out between pitch of a pulse train composed of alternating double and single pulses with pitch of pulse trains composed of single pulses. The alternating pulse train had a base rate of 400?pps, the pulse trains with solely single pulses had base rates of 200, 300, and 400?pps. The loudness and pitch perception of the different stimulus types were evaluated and compared. A significant loudness difference was found between single and double pulses for both pulse rates. The JND for pitch discrimination between double-pulse IPIs had a high inter-subject variability, and no significant group effect was found. No subject reported a pitch change between double pulse and single pulse stimulation. In contrast, most of the subjects recognized a change in pitch between single-pulse trains and pulse trains with alternating double and single pulses. The latter was lower in pitch than the single-pulse train stimulation. To conclude, using (equal amplitude) double pulses instead of single pulses in a pulse train does not effect pitch perception. Instead, loudness differs between double pulses and single pulses with the same amplitude.     

Long-term measurement of binaural intensity matches and pitch matches. I. Normal hearing

Changes in pitch perception and hearing thresholds over time have been observed in subjects with monaural fluctuating low-frequency hearing loss and Ménière's disease. Long-term suprathreshold audiometry and binaural pitch matches could provide information of these changes. Ten normal subjects were tested for stability of binaural intensity and pitch matches during 9–22 days in their homes with newly developed portable test equipment. Binaural pitch matches were measured using a 0.25- or 1-kHz reference tone presented at 60 dB SPL to one ear, and a loudness-matched test tone of adjustable frequency presented to the other ear. The results showed stable binaural intensity matches (individual inter-quartile ranges, IQRs, 1.2 to 5.7 dB), but binaural pitch matches varied greatly (IQR ?0.6 to 5.3% at 0.25 kHz; IQR ?1.6 to 7.9% at 1 kHz). Binaural pitch-matching was much better in subjects who could define pitch precisely during monaural pitch matching. It was concluded that in future long-term evaluations of patients with fluctuating inner-ear function, binaural intensity matches could be suitable for all, but binaural pitch matching only for selected patients.     

Effects of recurrent tonal information on auditory working memory for pitch

This study ascertained the influence of repeating pitch information within an intervening tonal sequence upon the extent of interference for a pitch standard held within auditory working memory as measured by the difference limen for frequency (DLF). Standard and comparison tones were presented to subjects and same/different responses were obtained using a touch screen monitor and the DLF was measured using single interval adjustment matrix (SIAM) procedure [Kaernbach, C., 1990. A single-interval adjustment-matrix (SIAM) procedure for unbiased adaptive testing. J. Acoust. Soc. Am. 88, 2645–2655]. Estimates of the DLF were obtained in a control condition with a silent inter-comparison interval and three conditions containing intervening tones within the temporal gap between the standard and comparison stimuli. The presence of intervening stimuli produced a significant increase in the DLF when the intervening tonal sequence contained tones with pitches that differed from that of the standard (Int condition) as well as when the sequence contained a tone with a pitch identical to that of the comparison (RptCmp condition). Further, the DLFs obtained for RptCmp condition were significantly higher than those measured in the Int condition. The DLFs measured in the condition where the pitch of an intervening tone was identical to the standard were significantly lower than those for the Int and RptCmp condition, but did not differ from the DLFs for the control condition. These results indicate that either a release from or an increase in interference in auditory working memory for pitch can occur dependent upon the frequency relationships between of the standard, comparison, and intervening tones.     

The effect of cochlear implantation on music perception by adults with usable pre-operative acoustic hearing

This study investigated the change in music perception of adults undergoing cochlear implantation. Nine adults scheduled for a cochlear implant (CI) were assessed on a music test battery both prior to implantation (whilst using hearing aids; HAs), and three months after activation of their CIs. The results were compared with data from a group of longer-term CI users and a group of HA-only users. The tests comprised assessments of rhythm, pitch, instrument, and melody perception. Pre-to-post surgery comparisons showed no significant difference in the rhythm, melody, and instrument identification scores. Subjects’ scores were significantly lower post-implant for ranking pitch intervals of one octave and a quarter octave (p=0.007, and p<0.001, respectively), and were only at chance levels for the smaller interval. However, although pitch perception was generally poorer with a CI than with a HA, it is likely that the use of both devices simultaneously could have provided higher scores for these subjects. Analysis of the other tests’ results provided insights into factors affecting music perception for adults with severe to profound hearing impairment.     

两种不同螺距扫描对头颈血管减影CTA成像影响的分析

目的 探讨两种不同螺距扫描对头颈血管减影CTA成像中图像质量和辐射剂量的影响,从而在不同头颈血管病变中选择合适的螺距进行扫描。方法 搜集2010年5月至2013年12月46例患者头颈血管减影CTA影像资料,按照螺距分成A、B两组各23例;A组扫描螺距为0.984,B组扫描螺距为0.516;对A、B两组图像中颈部动脉、颅底较大动脉及颅内动脉分支行主、客观分析,对容积再现（VR）、最大密度投影（MIP）图像采用主观分析进行评分,客观分析包括测量颈总动脉、颈内动脉及大脑前动脉分支CT值、本底噪声、信噪比,并统计辐射剂量。 结果 A、B组两种螺距扫描在颈部动脉及颅底较大动脉的主观评分、图像信噪比方面差异均无统计学意义（P均＞0.05）,平均CT值比较有统计学差异（P均＜0.01）,但CT值均＞300HU,其接近或处于血管成像合适的CT值范围,对成像不构成影响。A、B两组扫描对颈部动脉、颅底较大动脉解剖结构显示及颅底骨质去除影响不大;对颅内动脉分支主观评分、平均CT值、图像信噪比比较有统计学意义（P均＜0.05）,B组图像均优于A组图像,其显示颅内动脉分支更多、更细小、管壁更光整。 A组扫描的辐射剂量明显少于B组（P＜0.01）。结论 对于病变位于颈部或颅底较大血管处可使用0.984的螺距接受较少辐射剂量获得满意的减影CTA图像;对于怀疑颅内较小血管病变可使用0.516的螺距获得高质量的减影CTA图像,但须接受较多的辐射剂量。     

Shift of subjective reference and visual orientation during slow pitch tilt for the seated human subject

We examined the ability to assess subjective orientation and orientation of an external visual object during pitch titl. Subjects were seated, restrained, and in darkness in a simulator and estimated when they were 0°, 45°, and 90° forwards and backwards from upright during pitching at 1°/s. They temporarily stopped in these positions and set a 5 cm luminous cube, cockpit mounted at 60 cm from the nasium, to earth vertical. Estimates of subjective tilt were consistently greater than actual tilt. Overestimations were increased by preceding tilts in the opposite direction, particularly when tilting from forwards, where subjects sometimes estimated they were tilted backwards when the machine was tilted forwards. Subjects were surprised with their estimates, and reported disorientation. Regardless, settings of the visual vertical made “intuitively” were largely accurate. Subjective estimates could be construed as “accurate” if one assumes that the rostro-caudal axis of the head was referenced for estimates of upright and forwards and a trunk-leg axis for backwards. Because labyrinthine defective patients behaved as normal subjects, task performance must have been based on proprioception. The overestimation of tilt is exploited in fairground illusions and may account for the common experience when driving, that hills seem much steeper than they are.     

Ipsilateral acoustic electric pitch matching: A case study of cochlear implantation in an up-sloping hearing loss with preserved hearing across multiple frequencies

Abstract

Objectives

Determine ipsilateral acoustic electric pitch place match in a patient with preserved residual hearing across a broad frequency range.

Methods

Case report. Patient with up-sloping sensorineural hearing loss underwent implantation with a 680° insertion angle with preserved residual hearing. Pitch matching with variance of pulse rate was carried out.

Results

Electrical pitch percepts closely approximated the Greenwood map when compared to the acoustical pitch percepts and electrode position as determined by post-operative computed tomographic scan. The pitch matching results achieved from the deeply inserted electrodes, in the apical portion of the cochlea, suggest that the electrical stimulation may activate the dendritic extensions from the ganglion cell bodies that radiate from the terminal bulb. Stimulation rate influenced pitch perception in the apical turn but not in the mid- and basilar regions.

Discussion

Frequency to pitch allocation can potentially be improved by cochlear implants that access the apical third of the spiral ganglion. The ultimate goal of stimulating the apical third of the cochlea is to provide the maximum amount of spectral information to the user. We had the unique opportunity to work with a patient who presented with a severe sensorineural hearing loss rising to within normal limits and poor speech discrimination scores. Data from this study may aid our ability to give patients a broader spectrum of sound perception.     

声带振动模式及其变异的语音及电声门图分析

为更直观有效地了解正常男女性声带疾病患者在发声和声带振动的频率、幅度及声门开放、闭合过程的速度变化，我们采用嗓音测试仪观察正常男、女性声带振动的模式和声带疾病组的变异情况。将语言信号和电声门图信号的各个参数进行比较（ｔ检验）分析得出，健康男、女性波形规则均匀，女性频率快、幅度小，男性较女性的声门开放、闭合速度为快；疾病组中波形变化较大，频率或幅度都有不同的变化；嘶哑程度也不同地影响了声带运动中的开放和闭合过程。