Question about Philips Avent Dect SCD723/26

I am a hearing aid user and therefore have the following questions specifically about the vibra function: - How much does the device vibrate, for example, compared to the smartphone? rather weaker or stronger? - Is it a vibration or does the device vibrate until something is pressed? - can the buttons on the parent unit be locked? e.g. when the device is carried in a trouser pocket? I would appreciate your feedback - I have been looking for a suitable unit for hearing loss for some time. THANKS!