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首页> 外文期刊>The Journal of the Acoustical Society of America >Functional magnetic resonance imaging measurements of sound-level encoding in the absence of background scanner noise
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Functional magnetic resonance imaging measurements of sound-level encoding in the absence of background scanner noise

机译:在没有背景扫描仪噪声的情况下进行声级编码的功能磁共振成像测量

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摘要

Effects of sound level on auditory cortical activation are seen in neuroimaging data. However, factors such as the cortical response to the intense ambient scanner noise and to the bandwidth of the acoustic stimuli will both confound precise quantification and interpretation of such sound-level effects. The present study used temporally "sparse" imaging to reduce effects of scanner noise. To achieve control for stimulus bandwidth, three schemes were compared for sound-level matching across bandwidth: component level, root-mean-square power and loudness. The calculation of the loudness match was based on the model reported by Moore and Glasberg [Acta Acust. 82, 335-345 (1996)]. Ten normally hearing volunteers were scanned using functional magnetic resonance imaging (fMRI) while listening to a 300-Hz tone presented at six different sound levels between 66 and 91 dB SPL and a harmonic-complex tone (F_0 = 186 Hz) presented at 65 and 85 dB SPL. This range of sound levels encompassed all three bases of sound-level matching. Activation in the superior temporal gyrus, induced by each of the eight tone conditions relative to a quiet baseline condition, was quantified as to extent and magnitude. Sound level had a small, but significant, effect on the extent of activation for the pure tone, but not for the harmonic-complex tone, while it had a significant effect on the response magnitude for both types of stimulus. Response magnitude increased linearly as a function of sound level for the full range of levels for the pure tone. The harmonic-complex tone produced greater activation than the pure tone, irrespective of the matching scheme for sound level, indicating that bandwidth had a greater effect on the pattern of auditory activation than sound level. Nevertheless, when the data were collapsed across stimulus class, extent and magnitude were significantly correlated with the loudness scale (measured in phons), but not with the intensity scale (measured in SPL). We therefore recommend the loudness formula as the most appropriate basis of matching sound level to control for loudness effects when cortical responses to other stimulus attributes, such as stimulus class, are the principal concern.
机译:在神经影像数据中可以看到声音水平对听觉皮层激活的影响。然而,诸如皮质对强烈的环境扫描仪噪声和对声刺激的带宽的响应之类的因素将混淆这种声级效应的精确量化和解释。本研究使用时间“稀疏”成像来减少扫描仪噪声的影响。为了实现对刺激带宽的控制,比较了三种方案在整个带宽上进行声级匹配:分量级,均方根功率和响度。响度匹配的计算基于Moore和Glasberg报告的模型[Acta Acust。 82,335-345(1996)]。十名正常听力的志愿者使用功能磁共振成像(fMRI)进行了扫描,同时聆听了在66和91 dB SPL之间六个不同声级下呈现的300 Hz音调和在65和91 dB下呈现的谐波复音(F_0 = 186 Hz)。 85 dB声压级。声级范围涵盖了声级匹配的所有三个基础。相对于安静的基线条件,由八个音调条件中的每一个引起的上颞回中的激活被量化为程度和大小。声级对纯音的激活程度影响很小,但影响很大,而对谐波复音的影响不大,而对两种刺激的响应幅度都有很大影响。在纯音调的整个范围内,响应强度随声级线性增加。不管声音级别的匹配方案如何,谐波复调都比纯声调产生更大的激活,这表明带宽对听觉激活模式的影响大于声级。但是,当数据在刺激类别中崩溃时,范围和大小与响度标度(以发声单位为单位)显着相关,而与强度标度(以SPL为单位)无关。因此,当主要关注皮质对其他刺激属性(例如刺激类别)的响应时,我们建议将响度公式作为匹配声级的最合适基础,以控制响度效果。

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