They used the recording technique known as close miking where the microphone is less than from the singer's mouth. This produces a more intimate, less reverberant sound than when a singer is or more from the microphone. When using a pressure-gradient (uni- or bi-directional) microphone, it emphasizes low-frequency sounds in the voice due to the microphone's proximity effect and gives a more relaxed feel because the performer is not working as hard. The result is a singing style which diverged from the unamplified theater style of the musical comedies of the 1930s and 1940s.