Below are some YouTube videos offering test tones at various frequencies including sweeping tones, white noise, pink noise, and brown noises. White noise provides frequencies evenly spread across the entire spectrum from 20 to 20,000 Hz.
Pink noise is weighted with more sound at lower frequencies. Brown noise is like pink noise with even more emphasis on the base frequencies. You can use these frequencies to test audio systems and also discover how high and low you can hear.
Audio Spectrum Analyzers
Depending on the speakers, playing white nose should result in a frequency analyzer showing you a somewhat flat measurement of audio from about 40 – 60 Hz up to about 20,000 Hz indicating the frequency response of your speakers. Subwoofers will provide lower frequencies.
Keep in mind that other room noise will hinder the accuracy of the measurement unless you have a VERY quiet room.