The warning sounds from the Drive One device have a high frequency. This is to make the sounds as audible as possible. However, human ears are not identical, and therefore, some users might not find the sounds as clear/audible as others.
This is why we - by default - also play warning sounds through your phone speaker, or the car's stereo, if it is connected to your phone. If you find that the Drive One device's sounds are too low, we suggest adjusting the sounds that are played through your phone, so they suit your needs.