Mystery rapping noise

I went to my local repair shop and stumped the mechanic. My 2004 Camry has a strange noise coming from the front driver’s side area. The car has an automatic transmission, relatively new tires and brakes, and about 140,000 miles on it. Other than this mystery, the car has been phenomenal.

The noise starts after reaching 20-25 MPH, and it does not matter if I turn the wheel left or right or drive a straight stretch of road, or whether the cars is in gear or out of gear.

There is a noise that reminds me of the rhythmic rapping of a venetian blind cord hitting the window sill as it blows in the breeze. Sometimes the rapping occurs three times and stops. Sometimes it is as many as thirteen times before it temporarily stops. There is no pattern of how many times the rapping occurs that I can establish. I have varied speeds, steering, braking, and road conditions.

The noise is not loud as I cannot hear it when the window is open. I also cannot feel it in the steering or in the brakes.

Any suggestions?

Does the noise get faster with greater vehicle speed, or higher engine RPM? I know you said it doesn’t matter whether you’re turning, but does the noise perhaps get any louder/quieter when the wheel is turned one way or the other, as opposed to straight ahead?

The noise does not get faster with higher speeds or higher rpm. It maintains the same frequency between sounds regardless of speed.

It also does not vary in volume if the wheel is turned one way or the other or driving straight ahead.

Let’s see, since it isn’t sensitive to the speed of the engine or of the wheels and also not to the turning of the wheels, that eliminates the driveline components, and the internal and externally connected moving components of the engine. That’s a really good sign.

2004 with 140,000 miles? Only over 20 mph?
Perhaps there’s a loose wheelwell liner or mudflap or something of that sort being blown by turbulance.
Have you checked to see if you have a seatbelt hanging out?

Yes it sounds like something flapping in the breeze. Did you win anything for “stumping the mechanic”?