The capability of acoustic Doppler velocimeters (ADVs) to estimate suspended sediment concentration has been widely investigated using glass microspheres of the same size or well-sorted fractions in experimental studies. Sediment mixtures in the natural environment may have various types of grain size distribution. This study aims to investigate experimentally the acoustic response to probability distributions in suspension including quite coarse sediment fractions up to a diameter of 300 $\mathrm{\mu }$m. Modification of scattering and attenuation characteristics by introducing a size distribution is evaluated using the formulations given in the literature. In laboratory experiments, three different types of sediment size distributions constituting a wide size range of non-cohesive quartz sediments, namely uni-modal mass distribution, bi-modal mass distribution, and uniform number distribution, were generated. Acoustic backscatter measurements were made by immersing the ADV in a circulation tank filled with mixtures of sediments with known concentration and particle size distribution. Acoustic estimates of suspended sediment parameters obtained for different particle size distributions are compared with those for mono-size particle suspensions to show the effect of introducing a size distribution in suspension. The acoustic response from size distributions agrees with the general theoretical behavior such that the slope of the calibration curve decreases as the sediment size increases. The scattering and attenuation properties are modified compared to the mono-size suspension with the same mean size. In a region close to the geometric scattering regime, the backscattering coefficients for the particle size distributions are around 34% lower than those for mono-size particles, which results in lower backscattering strengths compared to the mono-size suspensions under the same concentration conditions. The sediment attenuation coefficient showed a smaller reduction (11%), resulting in a negligible change in the calculated signal corrected for water and sediment attenuation compared to the values for mono-size suspension of the same particle size. The information on the form of the probability distribution and the sorting of sediments in suspension is important for acoustic estimates of suspended sediment parameters. Introducing a particle size distribution affects the scattering properties more significantly than the attenuation properties for the geometric scattering regime.

声学多普勒测速仪（ADV）估计悬浮沉积物浓度的能力已在实验研究中使用相同大小或分数合理的玻璃微球进行了广泛研究。自然环境中的沉积物混合物可能具有各种类型的粒度分布。这项研究的目的是通过实验研究悬浮液中概率分布的声学响应，包括最大直径为300的较粗大的沉积物部分。$\mathrm{\mu }$米 使用文献中给出的公式，通过引入尺寸分布来评估散射和衰减特性的变化。在实验室实验中，生成了三种不同类型的沉积物粒度分布，它们构成了大范围的非粘性石英沉积物，即单峰质量分布，双峰质量分布和均匀数量分布。通过将ADV浸入装有已知浓度和粒径分布的沉积物混合物的循环罐中，进行声学反向散射测量。将针对不同粒径分布获得的悬浮沉积物参数的声学估算值与单一粒径悬浮液的声学估算值进行比较，以显示在悬浮液中引入粒径分布的效果。尺寸分布的声学响应与一般的理论行为一致，因此校准曲线的斜率会随着沉积物尺寸的增加而减小。与具有相同平均尺寸的单色悬浮液相比，散射和衰减特性得到了改善。在接近几何散射区域的区域中，粒径分布的反向散射系数比单一尺寸的颗粒低约34％，与相同浓度条件下的单一尺寸悬浮液相比，其反向散射强度较低。沉积物衰减系数显示出较小的减小量（11％），与相同粒径的单一尺寸悬浮液的值相比，校正后的水和沉积物衰减的计算信号变化可忽略不计。有关悬浮物中沉积物的概率分布和分类形式的信息对于悬浮物沉积参数的声学估算非常重要。引入粒度分布对散射特性的影响比对几何散射方案的衰减特性影响更大。