Loudness Differences for Voice-Over-Voice Audio in TV and Streaming

Voice-over-Voice (VoV) is a common mixing practice observed in news reports and docu- mentaries, where a foreground voice is mixed on top of a background voice, e.g., to translate an interview. This is achieved by ducking the background voice so that the foreground voice is more intelligible, while still allowing the listener to perceive the presence and tone of the background voice. Currently there is little published research on ducking practices for VoV or on technical details such as the Loudness Difference (LD) between foreground and background speech. This paper investigates the ducking practices of nine expert audio engineers and the preferred LDs of 13 non-expert listeners of ages 57 years and older. Results highlight a clear difference between the LDs used by the experts and those preferred by the non-expert listeners. Experts tended toward LDs of 11.5–17 LU, while non-experts preferred a range of 20–30 LU. Based on these results, a minimum LD of 20 LU is recommended for VoV. High inter-subject variance due to personal preference was observed. This variance makes a substantial case for the introduction of personalization in broadcast and streaming. The audiovisual material used for the tests is provided at https://www.audiolabs-erlangen.de/resources/2020-VoV-DB.