Frequency increasing problem

I hope this is the right area for this question. So I have this app idea and it requires a recorded audio clip of me saying a few words with a frequency of 14000-15000hz. I just tried recording some audio and increasing the pitch but that completely distorted the audio and made it intelligible and barely audible. Is there any way I can increase the pitch that much and somehow keep the audio somewhat intelligible?

For most people 15kHz is inaudible, effectively ultra-sonic : silent,
see …

Yeah I know, that’s kind of the point of my app. I tested with a few youtube videos and I could hear up to about 16000-16500hz so I should be able to hear it. When I changed the frequency to 15000hz, the soundwaves for the audiotrack almost disappeared. I’m not sure if the link you provided really helps with my issue. I want to record some speech, change the frequency to 15000hz and somehow keep the audio audible and comprehensible (obviously only for people that can hear within that frequency range).

That doesn’t make sense because voice requires a range of frequencies. For example, traditional telephone frequency response is about 4 octaves from 300 - 5000Hz. You loose the highest & lowest voice frequencies but it’s still intelligible. If you shift the bottom of that range to 16kHz, that’s a factor of about 50 and the range would be 16kHz to 250kHz.

The last few seconds of this are above 15kHz …

Ok, so I guess my idea won’t work but thanks for the help anyway!