I bought an alarm clock from Argos a few days ago to replace my oregon scientific alarm that had died after many years use. The clock from Argos was a standard alarm and I found that when it went off I could not hear it, it was so quiet. I know I am a little hard of hearing but not that bad. I took it back and since then I have tried another 3 alarm clocks in the shop and they are all so very quiet. My hearing problem is on the high frequency bands.
After doing some research on the best type I ordered this Sonic Boom SBA475SS and it is great. It is tone adjustable so if you have a problem hearing high or low frequencies you can set it to suit. There is a bright backlight that can be turned off and the alarm itself can be set for vibrate, sound or both, and of course off. Whatever the setting it flashes quite brightly when it goes off.
It is very easy to use and to see and the buttons etc are easily placed.
However when it goes off Stand Back!!!!!! There is no way you can sleep through this one! If the alarm is not enough, or if you do not want to wake a partner, or the whole street, the vibrating pad on a long lead can be placed under the pillow or on the side table. Under the pillow it will easily wake anyone and on a side table it rattles around so you could not fail to hear it.
An excellent little machine and very versatile and adjustable.