If your vehicle is showing rhythmic squeaking noise from underneath that speeds up as the car accelerates, here are the most likely causes and the parts you'll need to fix each one.
The needle bearings inside the driveshaft U-joint have dried out or rusted, causing a rhythmic 'chirping' or squeaking that increases with vehicle speed. This is highly common on rear-wheel and four-wheel drive vehicles.
The mechanical brake pad wear indicators are designed to scrape against the brake rotor when the pads are low. Slight rotor runout makes this scraping sound rhythmic, speeding up as the wheels turn.
If brake caliper slide pins lack lubrication, the brake pad can drag lightly against the rotor as it turns. This often happens after a recent brake job if the pins were not properly cleaned and greased.
While often producing a humming or growling noise, a failing wheel bearing can sometimes produce a rhythmic squeak or chirp if the internal seal fails and it loses lubrication, or if the excessive play causes the rotor to rub.
A torn CV boot allows grease to escape and dirt to enter. Before it degrades enough to start clicking heavily on turns, a dry CV joint can emit a rhythmic squeak as the axle rotates.
On vehicles with a two-piece driveshaft, the center support bearing can dry out and fail over time. This causes a squeaking or howling noise directly underneath the center of the vehicle that scales with speed.