The speed of sound in high-purity n-hexane and n-heptane was experimentally studied utilizing the double-path length pulse-echo technique. Measurements with each alkane were carried out at temperatures from (233 to 353) K with pressures up to 20 MPa. Considering the uncertainty contributions from temperature, pressure, path-length calibration, pulse timing and sample purity, the relative expanded combined uncertainty (k = 2) in the speed of sound in n-hexane ranges from (0.012 to 0.042) % over the investigated ranges of pressure and temperature; for n-heptane, the uncertainty varies from (0.014 to 0.018) %. The sound speed data measured in n-hexane were among the data used for the development of a new fundamental equation of state, which is, however, not described in this work. The experimental data of n-heptane can be considered appropriate for modeling purposes and validation of existing equations of state.

声音在高纯度的速度ñ -己烷和Ñ庚烷进行了实验研究利用双路径长度脉冲回波技术。在（233至353）K的温度下，以最高20 MPa的压力进行每种烷烃的测量。考虑从温度，压力，路径长度校准，脉冲定时和样品纯度的不确定度，相对扩展组合的不确定性（ķ 在声音在速度= 2）ñ来自所研究的（0.012〜0.042）％己烷范围压力和温度范围；对于正庚烷，不确定度为（0.014至0.018）％。中测得的声速数据Ñ正己烷是用于建立新的基本状态方程的数据之一，然而，本文未对此进行描述。可以认为正庚烷的实验数据适合用于建模目的和验证现有状态方程。