Titze Ingo R, Svec Jan G, Popolo Peter S
University of Iowa, Iowa City, USA.
J Speech Lang Hear Res. 2003 Aug;46(4):919-32. doi: 10.1044/1092-4388(2003/072).
To measure the exposure to self-induced tissue vibration in speech, three vocal doses were defined and described: distance dose, which accumulates the distance that tissue particles of the vocal folds travel in an oscillatory trajectory; energy dissipation dose, which accumulates the total amount of heat dissipated over a unit volume of vocal fold tissues; and time dose, which accumulates the total phonation time. These doses were compared to a previously used vocal dose measure, the vocal loading index, which accumulates the number of vibration cycles of the vocal folds. Empirical rules for viscosity and vocal fold deformation were used to calculate all the doses from the fundamental frequency (F0) and sound pressure level (SPL) values of speech. Six participants were asked to read in normal, monotone, and exaggerated speech and the doses associated with these vocalizations were calculated. The results showed that large F0 and SPL variations in speech affected the dose measures, suggesting that accumulation of phonation time alone is insufficient. The vibration exposure of the vocal folds in normal speech was related to the industrial limits for hand-transmitted vibration, in which the safe distance dose was derived to be about 500 m. This limit was found rather low for vocalization; it was related to a comparable time dose of about 17 min of continuous vocalization, or about 35 min of continuous reading with normal breathing and unvoiced segments. The voicing pauses in normal speech and dialogue effectively prolong the safe time dose. The derived safety limits for vocalization will likely require refinement based on a more detailed knowledge of the differences in hand and vocal fold tissue morphology and their response to vibrational stress, and on the effect of recovery of the vocal fold tissue during voicing pauses.
为了测量言语中自我诱发的组织振动暴露情况，定义并描述了三种嗓音剂量：距离剂量，它累积了声带组织颗粒在振荡轨迹中行进的距离；能量耗散剂量，它累积了声带组织单位体积上消散的总热量；以及时间剂量，它累积了总发声时间。将这些剂量与之前使用的嗓音剂量测量指标——嗓音负荷指数进行比较，该指数累积了声带的振动周期数。利用粘度和声带变形的经验规则，根据言语的基频（F0）和声压级（SPL）值计算所有剂量。要求6名参与者分别以正常、单调和夸张的方式朗读，并计算与这些发声相关的剂量。结果表明，言语中较大的F0和SPL变化会影响剂量测量，这表明仅累积发声时间是不够的。正常言语中声带的振动暴露与手部传递振动的工业限值有关，其中安全距离剂量约为500米。该限值对于发声来说相当低；它与大约17分钟连续发声的相当时间剂量相关，或者与正常呼吸和无声段情况下大约35分钟连续朗读的时间剂量相关。正常言语和对话中的发声停顿有效地延长了安全时间剂量。基于对手部和声带组织形态差异及其对振动应激反应的更详细了解，以及发声停顿期间声带组织恢复的影响，可能需要对得出的发声安全限值进行完善。
