I am searching for an easy solution for an exasperating nuisance. There is a public address system at work and before the start of the messaage a loud audio annunciator frequency has been added to warn people of the upcoming message and I want to locally supress it but still receive the message. The speaker is located just above my shop and do not want to interfere with the global annunciator but only this one speaker. I am an electrican who was trained in electronics decades ago and my idea is that when the annunciator tone is present, rectify it and pick up a relay that starts a delay on timer that blocks the signal until timing is completed. The annunciator tone is app. 900HZ to 1000HZ and centered around 950HZ as measured with an o'scope. The annunciator tone lasts for one second and is very disturbing and want to cancel it during that time and then have the timer close the circuit again to hear the message. That is it in a nut shell. I tried using a standard bridge rectifer powering a 5V relay but the relay would not pick up and if I can pick up the relay then the local problem will be solved. Please give me advice on how to accomplish my goal which will make all of the electricans happy in the electrical shop. Thanks for any and all responses.