Why is Higgins not interested in recording the girl's voice in Pygmalion?

In George Bernard Shaw's "Pygmalion," Professor Henry Higgins is initially uninterested in recording Eliza Doolittle's voice because he views her as a subject for his experiment rather than an individual with her own identity. He is more focused on the challenge of transforming her speech and manners to pass her off as a duchess than on the artistic or sentimental value of her voice. Additionally, Higgins's practical and scientific approach to phonetics prioritizes the mechanics of speech over emotional expression, leading him to dismiss the significance of capturing her natural voice.