Department of Otolaryngology/Head and Neck Surgery, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
Department of Health Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
Ear Hear. 2024;45(2):486-498. doi: 10.1097/AUD.0000000000001446. Epub 2024 Jan 5.
Audiometric testing typically does not include frequencies above 8 kHz. However, recent research suggests that extended high-frequency (EHF) sensitivity could affect hearing in natural communication environments. Clinical assessment of hearing often employs pure tones and frequency-modulated (FM) tones interchangeably regardless of frequency. The present study was designed to evaluate how the stimulus chosen to measure EHF thresholds affects estimates of hearing sensitivity.
The first experiment used standard audiometric procedures to measure 8- and 16-kHz thresholds for 5- to 28-year olds with normal hearing in the standard audiometric range (250 to 8000 Hz). Stimuli were steady tones, pulsed tones, and FM tones. The second experiment tested 18- to 28-year olds with normal hearing in the standard audiometric range using psychophysical procedures to evaluate how changes in sensitivity as a function of frequency affect detection of stimuli that differ with respect to bandwidth, including bands of noise. Thresholds were measured using steady tones, pulsed tones, FM tones, narrow bands of noise, and one-third-octave bands of noise at a range of center frequencies in one ear.
In experiment 1, thresholds improved with increasing age at 8 kHz and worsened with increasing age at 16 kHz. Thresholds for individual participants were relatively similar for steady, pulsed, and FM tones at 8 kHz. At 16 kHz, mean thresholds were approximately 5 dB lower for FM tones than for steady or pulsed tones. This stimulus effect did not differ as a function of age. Experiment 2 replicated this greater stimulus effect at 16 kHz than at 8 kHz and showed that the slope of the audibility curve accounted for these effects.
Contrary to prior expectations, there was no evidence that the choice of stimulus type affected school-age children more than adults. For individual participants, audiometric thresholds at 16 kHz were as much as 20 dB lower for FM tones than for steady tones. Threshold differences across stimuli at 16 kHz were predicted by differences in audibility across frequency, which can vary markedly between listeners. These results highlight the importance of considering spectral width of the stimulus used to evaluate EHF thresholds.
听力测试通常不包括 8 kHz 以上的频率。然而，最近的研究表明，扩展高频（EHF）敏感度可能会影响自然交流环境中的听力。临床听力评估通常交替使用纯音和调频（FM）音，而不考虑频率。本研究旨在评估用于测量 EHF 阈值的刺激选择如何影响听力敏感度的估计。
第一项实验使用标准听力测试程序，测量 5 至 28 岁听力正常者的 8 和 16 kHz 阈值，测试频率范围为 250 至 8000 Hz。刺激物为稳态音、脉冲音和 FM 音。第二项实验使用心理物理程序测试 18 至 28 岁听力正常者的标准听力测试范围，评估频率变化对敏感度的影响如何影响检测具有不同带宽的刺激物，包括噪声带。使用稳态音、脉冲音、FM 音、窄带噪声和 1/3 倍频程噪声，在一只耳朵的一系列中心频率下测量阈值。
在实验 1 中，8 kHz 时年龄越大阈值越低，16 kHz 时年龄越大阈值越高。在 8 kHz 时，个体参与者的稳态、脉冲和 FM 音的阈值相对相似。在 16 kHz 时，FM 音的平均阈值比稳态或脉冲音低约 5 dB。这种刺激效应不因年龄而异。实验 2 复制了在 16 kHz 时比在 8 kHz 时更大的刺激效应，并表明可听度曲线的斜率解释了这些效应。
与先前的预期相反，没有证据表明刺激类型的选择对学龄儿童的影响大于成人。对于个体参与者，16 kHz 时 FM 音的听力阈值比稳态音低 20 dB 以上。16 kHz 时不同刺激之间的阈值差异由频率之间的可听度差异预测，而可听度差异在不同听众之间可能有很大差异。这些结果强调了考虑用于评估 EHF 阈值的刺激光谱宽度的重要性。
