Frequency Ranges
Average human hearing spans a frequency range from about 20Hz to about 17000Hz. The figure below shows some common sounds and the frequency range they cover. Figure: Frequency Range of Sounds
Many people wonder why it is difficult to remove vocals from music. From the figure, you'll see there is a large overlap in the frequency range of speech and music. Removing the vocals would also remove a significant part of the music. A similar problem occurs when removing hiss noise, since it often covers the entire spectrum.
Most basic stereo systems have bass and treble controls, which offer limited control over a frequency spectrum. Bass applies to low frequency sounds, such as drums, cellos, low piano notes, or a hum noise. Treble applies to high frequency sounds, such as a clash of cymbals, a tweet of a small bird, high notes on a piano, or a hiss noise.
More expensive stereo systems have Graphic Equalizers, which provide better control over a frequency spectrum. Instead of controlling just two bands (bass and treble), you can control many bands.
GoldWave provides even more control over frequency spectrums with filter effects such as Parametric EQ, Low/Highpass, Bandpass/stop, Equalizer, Noise Reduction, and Spectrum Filter.