Sound phase shift.

[wallabybob]

Hello Group,
I am a newbie to this group and i am currently doing some research of phase shifting
sound frequencies. I have limited knowledge on this subject so i would appreciate any feedback from group members. I would like to phase shift a given frequency of say
7000 hz. I am looking at using an electronic digital device that could be used to receive a 7000 hz signal and then convert it sequencially at 6 degrees phase shift for 30 seconds, then followed by 12 degrees for 30 seconds, 18 degrees, 24, 30, 36, through
to 360 degrees over 30 minutes, then deliver the phase shift pure sine tones to a set of
headphones. This should act as a shotgun method of cancelling out perceived sound waves. Would it be possible to design some type of electronic device to successfully cancel out noise or sounds. Hope you can make sense of this, but i know it can work.
I have been told software can do this, but feel some hardware device would be a better option. Thankyou johnny

 

[Farview]

If I understand you correctly, you are trying to use phase shift to cancel certain frequencies in a set of headphones.

The important thing to know about phase is that it is a relationship. In order for something to be phase shifted, you have to be comparing it to something else. A single signal has no phase.

If you are talking about phase shifting a specific frequency of a signal and combining it with the original signal to cause cancellation, you have just described an EQ.

Since people don't generally listen to sine waves, just turning down 7k is going to be useless unless you are listening to something with too much 7k in it.

If you are trying to design noise canceling headphones, it's already been done. The headphones have a mic and an amplifier that feeds the signal coming into the mic into the headphones 180 degrees out of phase. This cancels the outside noise out before it gets to the listeners ear.

Of course, maybe I missed your entire point. What are you tring to accomplish?