now you need to clean the bottom of th transmission and check for leaks. I'll bet your seals are leaking

 

Right of the top of my head, I would say it's your airbox. There might be a crack in it if it's the stock plastic one. I only suggest this because I have a 99 accord 4cyl, so I know your engine. And that's pretty much the only thing on the right side of the car that could be causing that. Pretty hard tho, since I cant get a good description of the noise. I know mine makes a whistling sound when it's cold out at night, but that's only cuz I have an AEM cold air intake on mine lol. SO i love that sound.