The influence of the low-frequency roll-off and phase distortion of sound level meters (SLMs) on rocket noise metrics based on measured data is studied. Specifically, during the take-off of a space launch vehicle (SLV) called the Taurus, environmental sound pressure was measured with a carrier microphone system. This system has a virtually flat frequency response at low frequencies. In this study, the low-frequency response of SLMs was simulated using high pass filters. Two sets of filters with the same response magnitude were used: with and without phase distortion. It was shown that, for SLVs with small engines (e.g., the Delta, Scout, and Taurus), the low-frequency distortion resulting from measurements with (simulated) SLMs is apparent only in sound pressure power spectral densities (PSDs) of high resolution at frequencies below 10 Hz. This is where PSD levels are already more than 10 dB below the peak levels. There is no significant effect on the skewness of the time domain data nor on the time-energy averaged sound pressure level (SPL). It is shown that for SLVs with large engines the low-frequency response of the typical SLM results in a significant increase in the skewness of the data as peak (positive) shock pressures are increased. Comparisons of the effects of the two high pass filters indicate that the phase of the frequency response is a critical factor in the distortion of the data.