Marlina Deasy Hartanto submitted a paper on Lehmann called “Exploring Expressive Lied Performance: Re-enacting Lotte Lehmann’s Pre-World War II Lied Performances,” as a master project for the Royal Conservatoire of The Hague on November 9, 2021. We were able to access it at without charge at ResearchCatalogue.net on June 26, 2023.
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Hartanto uses as examples of Lehmann’s singing “An die Musik” and “Ich grolle Nicht” and assumes that they were recorded “acoustically” (using a horn instead of a microphone), but in each case, these were “electric” recordings, as were all of Lehmann’s discs from 1927 on. The great advantage of a modern thesis paper is that the author can provide the very sound she wishes to analyze.