double knocking-click or engage-disengage sound

I have a 2006 Prius just shy of 256,000 miles. I'm not quite sure how to describe this sound that I've been hearing intermittently. It seems like I hear it at lower speeds around the interval of using the break and/or the accelerator, like maybe when it switches from electric to ICE and/or vice-versa. I will see if I can get a recording of it. I might describe it as a double knocking-click or engage-disengage sound. It is not a sharp sound and the two parts of the sound are not equal length or sharpness.

Ideas on what it might be?

Thanks,

Brian

 

It is definitely coming from the front. I don't know If it is brake, suspension, transmission, or engine. I hear it more clearly with my window down. I very rarely have a passenger with me to get a second listen on it and I don't drive my car much. I may just take it to a mechanic and see if it happens with them in the car.

 

Thanks, Paul's shop replaced my 12V battery and an inverter coolant pump recently.

 

I now have a sound file. How do I upload a sound file and what formats work?

 

I had to take a video of my sound file to be able to post it to youtube. here is the link. The sound happens twice, once around 1 second and the other around 4 second-mark. Darn, you are going to have to listen to it on the external youtube link. Click on the Watch on YouTube link in the video frame.