One way to work on developing a softer, more feminine voice without surgery is through vocal exercises that focus on pitch adjustment, resonance practice, and tone modulation. Here are some techniques you can try:

1. Pitch adjustment: Start by practicing speaking in a higher pitch. You can do this by humming at a higher frequency or simply raising the pitch of your voice gradually during conversations. Consistent practice can help you develop a more feminine pitch over time.

2. Resonance practice: To achieve a more feminine resonance, try speaking from your head voice rather than your chest voice. Focus on feeling the vibrations in your head or face while speaking. You can also practice nasal resonance by allowing some of the sound to resonate in your nasal passages.

3. Tone modulation: Work on varying your intonation and inflection to create a more melodic and expressive voice. Practice speaking in a more animated and engaging manner to add a feminine touch to your voice.

Additionally, working with a speech therapist or vocal coach can provide personalized guidance and feedback to help you refine your voice further. They can tailor exercises to your specific needs and help you achieve your desired vocal transformation more effectively.

Consistent practice, patience, and guidance from a professional can help you develop a softer, more feminine voice naturally over time. Remember that changes in voice may take time, so be persistent in your practice and seek support when needed.