While it's not possible to completely change one's voice to sound exactly like the opposite gender's using just their natural speaking tone, there are techniques that can help a woman lower the pitch of her voice to create a deeper, more masculine sound over the phone. Here are some tips:
Relax and speak from the chest: Take deep breaths and try to relax your vocal muscles. Speaking from your chest rather than your throat can help create a deeper resonance. Practice speaking in a relaxed, deeper tone.
Slow down your speech: Speaking at a slower pace can give your voice a deeper quality. It allows for more control over the pitch and helps avoid unintentional higher pitch variations.
Use a lower vocal range: Experiment with finding the lower end of your vocal range. Practice speaking from that lower range, emphasizing the lower notes while avoiding straining or sounding unnatural.
Focus on intonation and inflection: Men and women often use different patterns of intonation and inflection. Listen to how men speak and try to imitate their speech patterns, emphasizing downward inflections and flatter intonation.
Pay attention to resonance: Resonance is the way sound vibrates in your throat, mouth, and nasal cavities. Men tend to have a lower and more pronounced resonance. Experiment with positioning your voice in your chest and mouth to create a deeper resonance.
Practice speaking in a deeper voice: Spend time practicing speaking in a deeper voice. You can record your voice and listen to the recordings to evaluate your progress and make adjustments as needed.
Remember, these techniques can help create a deeper voice, but they might not completely mimic a man's voice. If you need to consistently sound like a man over the phone for professional purposes, you might consider using voice modulation technology or seeking guidance from a speech therapist or vocal coach who can provide personalized training and exercises.